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1
Chou, Tsong-Yung, Chien-Kuo Wang, A. C. Lua, and Hsueh-Hui Yang. "A simple and high throughput parallel dual immunoaffinity liquid chromatography-mass spectrometry system for urine drug testing." Analytical Methods 10, no. 8 (2018): 832–35. http://dx.doi.org/10.1039/c7ay02755a.
Повний текст джерелаАнотація:
A simple and rapid method for direct quantitation of drugs in human urine samples was developed using a system composed of an automatic column switch and two home-made capillary immunoaffinity columns (CIACs, 100 μm × 15 cm).
2
Evans, R. Douglas, Andrei Izmer, Karima Benkhedda, Andrew Toms, Angelo Fernando, and Wei Wang. "Continuous online determination of 226Ra in liquid effluents using automated column chromatography-ICP-MS." Canadian Journal of Chemistry 93, no. 11 (November 2015): 1226–31. http://dx.doi.org/10.1139/cjc-2015-0247.
Повний текст джерелаАнотація:
A measurement system capable of continuous on-line matrix removal, pre-concentration and analysis of 226Ra using pre-packed columns coupled to a flow injection system and an ICP-MS was developed. Full instrumental control of both the ICP-MS and the flow injection system provided automatic integration of the transient signals. The flow injection system was programmed to control column conditioning, sample loading, column rinsing, analyte elution and column cleaning operations employing appropriate solutions. The application of this system to the 226Ra analysis of an industrial liquid effluent was demonstrated. Using this particular instrument together with pre-concentration and matrix removal procedures, a limit of detection of 5.4 fg L−1 (2 mBq L−1) and a method detection limit of 16.2 fg L−1 (6 mBq L−1) were achieved for the measurement of 226Ra using a 25 mL sample volume. Total time for sample handling and analysis is approximately 10 minutes. The concentration of 226Ra in a discharged effluent sample was 0.73 pg L−1 (27 mBq L−1), which is in good agreement with the value of 0.81 pg L−1 (30 mBq L−1) measured using conventional alpha counting techniques.
3
Chase, G. William, and Brian Thompson. "Accelerated Solvent Extraction of Vitamin K1 in Medical Foods in Conjunction with Matrix Solid-Phase Dispersion." Journal of AOAC INTERNATIONAL 83, no. 2 (March 1, 2000): 407–10. http://dx.doi.org/10.1093/jaoac/83.2.407.
Повний текст джерелаАнотація:
Abstract An extraction technique is described for vitamin K1 in medical foods, using accelerated solvent extraction (ASE) in conjunction with matrix solid-phase dispersion (MSPD). The medical food sample is treated as it would be with MSPD extraction, followed by ASE for a hands-free automated extraction. The vitamin K1 in the ASE extract is then quantitated by reversed-phase liquid chromatography with fluorescence detection. The chromatography specifications are identical to those in previous work that used MSPD only, with a limit of detection of 6.6 pg and a limit of quantitation of 22 pg on column. Recoveries, which were determined for an analyte-fortified zero control reference material for medical foods, averaged 97.6% (n = 25) for vitamin K1. The method provides a rapid, automatic, specific, and easily controlled assay for vitamin K1 in fortified medical foods with minimal solvent usage.
4
Vargas-Bustamante, Jaquebet, Pedro Martínez-Ortiz, Daniel Alvarado-Alvarado, Ulises Torres-Herrera, and Jorge Balmaseda. "Experimental Setup and Graphical User Interface for Zero-Length Column Chromatography." Applied Sciences 12, no. 13 (July 1, 2022): 6694. http://dx.doi.org/10.3390/app12136694.
Повний текст джерелаАнотація:
This work describes the design and implementation of a Zero-Length Column system to measure: diffusion coefficients, adsorption isotherm parameters of pure components and mixtures. In addition, a graphical user interface (GUI) was developed in LabVIEW for the semi-automatic operation of the system. The system is novel because it integrates all the aforementioned functionalities without using mass spectrometry. Two adsorbents, zeolite 5A and Basolite® C300 (Copper benzene-1,3,5-tricarboxylate) and two adsorbates methane and ethane were used to perform the validation of adsorption and diffusion experiments. The Henry constants and diffusion coefficients obtained reproduce those previously reported. The combination of the experimental setup and the GUI significantly reduce the amount of sample and measurement time needed in the characterization of the molecular sieves by conventional volumetric and gravimetric systems. The proposed system is relatively inexpensive, robust, easy to build, and capable of reproducing the results of other techniques.
5
Fischer, W. G., and P. Kusch. "Automatic sampler for curie-point pyrolysis-gas chromatography with on-column introduction of pyrolysates." Journal of Chromatography A 518 (January 1990): 9–19. http://dx.doi.org/10.1016/s0021-9673(01)93158-9.
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6
Einarsson, Östen, and Lars Hansén. "A PC-controlled module system for automatic sample preparation and analysis." Journal of Automatic Chemistry 17, no. 1 (1995): 21–24. http://dx.doi.org/10.1155/s1463924695000034.
Повний текст джерелаАнотація:
A simple automatic analytical system, consisting of separate modules, for liquid chromatography has been constructed. The different parts of the automatic machine are an auto sampler, an auto dispenser, a selector valve with eight channels, a heater/cooler, a mixing chamber and a pressure air driven injector valve. The process was controlled by a PC from an easily changeable run protocol. The system was applied to analysis of primary amines. The analysis was performed as a pre-column derivatization reaction of the amines and separation by isocratic reversed-phase HPLC with fluorescent detection. Reproducibility and analytical precision have been studied. Comparison between automatically and manually made derivatization reaction and injection was also made. The automatic system was easy to handle, cost-effective and gave good reproducibility.
7
Moats, William A., and Laura Leskinen. "Determination of Novobiocin Residues in Milk, Blood, and Tissues by Liquid Chromatography." Journal of AOAC INTERNATIONAL 71, no. 4 (July 1, 1988): 776–78. http://dx.doi.org/10.1093/jaoac/71.4.776.
Повний текст джерелаАнотація:
Abstract Residues of novobiocin in milk, blood, and tissues can be detected by microbiological tests but cannot be distinguished from other antibiotics. A simple liquid chromatographic (LC) method was developed for identification of residues. Tissues were blended and milk and blood serum were mixed with 0.2M NH4H2P04. The mixture was deproteinized by adding aqueous methanol and filtering. The LC apparatus consisted of a variable wavelength detector, set at 340 nm, an automatic loop injector, and a C,8 column with guard cartridge. The flow rate was 1 mL/min and the solvent mixture of 0.01M H3P04-acetonitrile-methanol was programmed from 50 + 0 + 50 (0-1 min) to 20 + 80 + 0 (20 min). Novobiocin was concentrated directly by solid-phase extraction on the analytical column. Five or more 200 11L aliquots of the filtrate in water-methanol (1 + 1) (adjusted if necessary) were injected with the column solvent at 50 + 0 + 50. After the final injection, the program was run to completion. Recoveries were 90-100% with sensitivities of 0.05 ppm or less. The procedure should be adaptable for use with formulations and feeds
8
Zhou, Fei-Yang, Dong He, Xin Miao, Chun Yang, Jun-Hang Dong, Hong-Tao Zheng, Zhuo Cheng, Xing Liu, and Zhen-Li Zhu. "Development of an Automatic Column Chromatography Separation Device for Metal Isotope Analysis Based on Droplet Counting." Analytical Chemistry 93, no. 19 (May 10, 2021): 7196–203. http://dx.doi.org/10.1021/acs.analchem.1c00145.
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Zhang, Li Ming, Yan Qiao Wang, Li Chao Zhang, Shu Li Man та Bei Mei Zuo. "Purification and Characterization of a Yam Glycoprotein Isolated by Alkaline Extraction from Yam Tuber". Advanced Materials Research 560-561 (серпень 2012): 368–73. http://dx.doi.org/10.4028/www.scientific.net/amr.560-561.368.
Повний текст джерелаАнотація:
Yam glycoprotein (YGP) is an important source of bioactives for functional foods. To investigate the effects of alkaline extracting method on the features of YGP, A glycoprotein was isolated from yam tubers by using alkaline processing method, and purified by ion-exchange and gel filtration column chromatography. During the SDS-PAGE eletrophoresis, the result shows a band with approximately 30 kDa molecular weight. The YGP consists of protein moiety (62.34%) and carbohydrate moiety (37.51%), respectively. By the automatic amino acid analyzer detecting, it indicated that the YGP consists of 17 kinds of amino acids and contains a high percentage of glutamic acid and aspartic acid. The results of thin-layer chromatography show that oligosaccharides of the YGP contain D-glucose, D-galactose and mannose.
10
Suzuki, Yukio. "Determination of low-molecular-mass organic acids in fogwater by ion-exchange chromatography with automatic column switching." Journal of Chromatography A 773, no. 1-2 (June 1997): 123–30. http://dx.doi.org/10.1016/s0021-9673(97)00113-1.
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11
Nguyen, Duy Hung, Yu V. Snigireva, A. V. Taneeva, and V. F. Novikov. "Influence of the nature of organic solvents on the process of separation of antioxidative additive in a transformer oil by a gas-chromatographic method." Power engineering: research, equipment, technology 22, no. 6 (March 26, 2021): 211–20. http://dx.doi.org/10.30724/1998-9903-2020-22-6-211-220.
Повний текст джерелаАнотація:
THE PURPUSE. The paper considers the influence of the nature of organic solvents on the process of separation of an antioxidant additive added to transformer oil at a concentration of up to 0.40% by weight, and organic solvents used as selective extractants. Based on the analysis of literature data, it is shown that mineral transformer oil is a complex hydrocarbon composition that undergoes oxidative degradation during operation, leading to aging of transformer oil and deterioration of technical conditions of operation of transformer electrical equipment. As a result of this process, peroxide compounds appear in transformer oil, which affect its color, oxidation stability, aging resistance, compatibility with structural parts of equipment, etc. Gas -liquid chromatography was used to determine the "Ionol" antioxidant additive and organic extractants in transformer oil. Experiments were performed on a chromatograph of Chromosomes GC -1000 with a flame ionization detector and a quartz capillary column 30 m long, 0.32 mm in diamet er, filled with a fixed liquid phase Valko Bond VB-WAX P/n with a film thickness of 0.5 microns. The sample was dosed into the gas-liquid chromatograph injector using an automatic liquid dispenser DAZH-23, designed for entering up to twenty-three samples of sorbates and controlled by a computer with the appropriate software.METHODS. Aliphatic alcohols from C1 to C5 were studied as extractants of the antioxidant additive, which are well separated from the ionol both under isothermal conditions and in the mode of linear programming of the column temperature from 40 to 220 °C. Under these conditions the chromatogram of the separation of antioxidant additives, and aliphatic alcohols, which are used to calculate their relative retained volumes, the asymmetry of chromatographic peaks and the column efficiency, which depends on the physico -chemical nature of the solutes to be analyzed and the conditions of the chromatographic experiment.RESULTS. The dependence of the relative volume of retention of aliphatic alcohols on their permittivity, which has a nonlinear form, is established. At the same time, with a decrease in the chain length of alkyl substituents in the aliphatic alcohol molecule, there is a tendency to increase their permittivity. The dependence of the relative retained volume of aliphatic alcohols on the selectivity coefficient of separation with Ionol is linear. In this case, the most optimal separation selectivity, approaching one, is characteristic of the Ionol – Butanol-1 pair. It is shown that the dependence of the logarithm of the retention time of aliphatic alcohols on their boiling points is linear both at a low temperature of the chromatographic column (40 °C) and at a higher temperature (more than 100 °C). CONCLUSION. At the same time, the angle of inclination of the corresponding lines changes in the boiling point of organic solvents, which is associated with a change in the sorption mechanism in a capillary chromatographic column filled with a polar stationary phase.
12
Vrubel, Olha, Igor Nektegaev, and Volodymyr Antonyuk. "INVESTIGATION OF THE CHEMICAL COMPOSITION AND EFFICIENCY OF SEED OIL OF SPINDLE TREE (EUONYMUS EUROPAEA L.) ON THE MODEL OF NON-ALLERGIC DERMATITIS." EUREKA: Health Sciences 3 (May 31, 2018): 45–54. http://dx.doi.org/10.21303/2504-5679.2018.00649.
Повний текст джерелаАнотація:
The aim of the research was to study the chemical composition and effectiveness of the seed oil of Spindle tree (Euonymus europaea L.) on the non-allergic contact dermatitis model. The oil was obtained by the extraction by petroleum ether from the seeds. The analysis of fatty acids and determination of their quantitative content was carried out using gas chromatography. Determination of carotenoids and tocopherols content in fatty oils was carried out after chromatography on a silica gel column. Investigation of anti-inflammatory action of the Spindle tree seed oil on white rats was carried. Determination of biochemical parameters of blood plasma was performed on the semi-automatic biochemical analyzer BS3000M (Poland). The yield of oil was 20–28 % of the weight of the seeds. Nine fatty acids were identified in the oil by the gas chromatography, among which 4 are unsaturated (oleic, palmitoleic, linoleic and linolenic), which together make up 87.79 % of all fatty acids from this oil. Spindle tree oil contains 26±5 mg – % carotenoids and 40±5 mg – % tocopherols, which were separated by chromatography on a silica gel column. There were no symptoms of intoxication with the introduction of Spindle tree oil in the stomach of rats and it can be classified in the 4 the grade of danger in accordance with GOST 12.1.005-88. The anti-inflammatory activity of Spindle tree oil in comparison with the oil of Sea buckthorn on the model of non-allergic contact dermatitis was weaker, but sufficient to recommend it for the treatment of skin diseases in ointments.
13
Robitaille, Line, and L. John Hoffer. "Measurement of branched chain amino acids in blood plasma by high performance liquid chromatography." Canadian Journal of Physiology and Pharmacology 66, no. 5 (May 1, 1988): 613–17. http://dx.doi.org/10.1139/y88-095.
Повний текст джерелаАнотація:
A simple and rapid high performance liquid chromatographic technique is described for the separation and quantitation of plasma branched chain amino acids. After addition of a norleucine internal standard, plasma samples are acidified with acetic acid, and amino acids are separated from proteins and other plasma components by passage of the acidified plasma through an ion exchange resin. The ammonium hydroxide eluate from the resin is dried, phenylisothiocyanate derivatives are prepared, and the amino acids are separated on a Waters reverse-phase "Pico-Tag" column with an ultraviolet detector set at 254 nm. In addition to the branched chain amino acids (leucine, valine, and isoleucine), aspartate, glutamate, serine, threonine, alanine, and methionine are quantitated with high precision and accuracy, as verified by quantitative recovery and comparison with an automatic amino acid analyzer. The advantages of the method are its simplicity, speed, stability of derivatives, high reproducibility, low per-sample cost, and the use of a simple fixed-wavelength ultraviolet detector.
14
Turcant, A., A. Premel-Cabic, A. Cailleux, and P. Allain. "Screening for neutral and basic drugs in blood by dual fused-silica column chromatography with nitrogen-phosphorus detection." Clinical Chemistry 34, no. 7 (July 1, 1988): 1492–97. http://dx.doi.org/10.1093/clinchem/34.7.1492.
Повний текст джерелаАнотація:
Abstract We describe a capillary gas-chromatographic method for detection and quantification of basic and neutral drugs in the plasma of patients thought to be poisoned after dangerous overdose. Without further derivatization, the drugs are extracted from 1 mL of plasma, at basic pH, into diethyl ether. The extracts are injected onto two fused-silica capillary columns of different polarity (Ultra 1 and CP Sil 19 CB) coupled to nitrogen-phosphorus detectors. Under these conditions, drug-free plasmas give blank chromatograms, with a peak only for the internal standard (RN 927, an antihistamine not being marketed). Plasma samples from patients who have taken drugs show additional peaks, the relative retention times (RRTs) of which are used to identify the drugs. Here we list the RRTs of about 200 drugs on the two columns. Analyses are routinely performed with an automatic injector; overall analysis time is about 1 h per sample. During the last six years, more than 1000 plasma samples per year have been analyzed. We find this method a powerful tool for toxicological analysis, especially in cases of multi-drug intoxications.
15
Izquierdo-Pulido, M. L., M. C. Vidal-Carou, and A. Marine-Font. "Determination of Biogenic Amines in Beers and Their Raw Materials by Ion-Pair Liquid Chromatography with Postcolumn Derivatization." Journal of AOAC INTERNATIONAL 76, no. 5 (September 1, 1993): 1027–32. http://dx.doi.org/10.1093/jaoac/76.5.1027.
Повний текст джерелаАнотація:
Abstract A liquid chromatographic method is described for the determination in one run of the following 10 biogenic amines in beers: histamine, tyramine, serotonin, (β-phenylethylamine, tryptamine, cadaverine, putrescine, agmatine, spermine, and spermidine. The method is based on ion-pair chromatographic partition on a reversed-phase column and involves a postcolumn reaction with o-phthalaldehyde (OPT) to form fluorescent derivatives with amines. Treatment of beer samples before injection requires only a filtration through a 0.45 μm filter. It is necessary to obtain a perchloric extract for analysis of raw materials (malt and hops). The method was tested for lack of interference from amino acids and other amines. Linearity, precision, recovery, and sensitivity were satisfactory. Detection limits ranged from 0.30 to 0.40 mg/L, and determination limits ranged from 0.40 to 0.50 mg/L, except for serotonin and spermine, which were slightly higher. The simple preparation of sample and the automatic accomplishment of derivatization steps considerably reduce analysis time and effort.
16
Memon, Najma, Tahira Qureshi, Muhammad Iqbal Bhanger, and Muhammad Imran Malik. "Recent Trends in Fast Liquid Chromatography for Pharmaceutical Analysis." Current Analytical Chemistry 15, no. 4 (July 3, 2019): 349–72. http://dx.doi.org/10.2174/1573411014666180912125155.
Повний текст джерелаАнотація:
Background: Liquid chromatography is the workhorse of analytical laboratories of pharmaceutical companies for analysis of bulk drug materials, intermediates, drug products, impurities and degradation products. This efficient technique is impeded by its long and tedious analysis procedures. Continuous efforts of scientists to reduce the analysis time resulted in the development of three different approaches namely, HTLC, chromatography using monolithic columns and UHPLC. Methods: Modern column technology and advances in chromatographic stationary phase including silica-based monolithic columns and reduction in particle and column size (UHPLC) have not only revolutionized the separation power of chromatographic analysis but also have remarkably reduced the analysis time. Automated ultra high-performance chromatographic systems equipped with state-ofthe- art software and detection systems have now spawned a new field of analysis, termed as Fast Liquid Chromatography (FLC). The chromatographic approaches that can be included in FLC are hightemperature liquid chromatography, chromatography using monolithic column, and ultrahigh performance liquid chromatography. Results: This review summarizes the progress of FLC in pharmaceutical analysis during the period from year 2008 to 2017 focusing on detecting pharmaceutical drugs in various matrices, characterizing active compounds of natural products, and drug metabolites. High temperature, change in the mobile phase, use of monolithic columns, new non-porous, semi-porous and fully porous reduced particle size of/less than 3μm packed columns technology with high-pressure pumps have been extensively studied and successively applied to real samples. These factors revolutionized the fast high-performance separations. Conclusion: Taking into account the recent development in fast liquid chromatography approaches, future trends can be clearly predicated. UHPLC must be the most popular approach followed by the use of monolithic columns. Use of high temperatures during analysis is not a feasible approach especially for pharmaceutical analysis due to thermosensitive nature of analytes.
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Balymova, Maria V., Konstantin Ye Burkin, Ainaz Z. Gainullin, Alena Yu Likhacheva, and Mikhail Ye Zhilkin. "Revealing the falsification of semi-finished beef products with mechanically deboned minced chicken using the example of dumplings." Butlerov Communications 64, no. 12 (December 31, 2020): 40–44. http://dx.doi.org/10.37952/roi-jbc-01/20-64-12-40.
Повний текст джерелаАнотація:
Human nutrition is an important factor affecting human health. Counterfeiting is one of the most pressing problems in the market, which worries manufacturers, sellers and consumers. There are a variety of product counterfeiting: substitution of expensive food products for cheaper ones, manufacturing of products with low nutritional value, deterioration of the recipe and plagiarism of the brand. It is also necessary to observe the correct labeling of the product, as this enables the consumer to meet his requirements when choosing a product. This article presents the results of our own research revealing the falsification of semi-finished beef products with mechanically deboned minced chicken using the example of dumplings. In the analysis, four fatty acids were selected for the presence or absence of chicken fat in ground beef. The determination of fatty acids was carried out by gas chromatography. Gas chromatographic analysis is considered to be effective for identifying food products due to its high degree of sensitivity, speed and simplicity. Sample preparation stages included the use of sodium methoxide in methanol with a molar concentration of 2 mol/dm3. Gas chromatographic analysis was carried out on a flame ionization detector with a quartz capillary column. For simplicity, reduction of sample preparation time and better results, the samples were filtered under vacuum at atmospheric pressure, which significantly accelerated the filtration process. The analysis of the test sample was carried out in an automatic mode according to the specified program of the chromatograph. Myristic, palmitoleic, margaric, stearic, linoleic, and arachidic acids were chosen as “labels” of fatty acids. It has been shown that even an insignificant addition of one type of impurity of another to meat leads to a change in the fatty acid composition of the product.
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Nurislamova, Tatyana V., T. S. Ulanova, N. A. Popova, and O. A. Maltseva. "METHODOLOGICAL SUPPORT OF CONTROL OF THE CONTENT OF N-NITROZODIPHENYLAMINE IN FOOD MEAT AND MEAT/PLANT PRODUCTS." Hygiene and sanitation 97, no. 1 (January 15, 2018): 85–89. http://dx.doi.org/10.18821/0016-9900-2018-97-1-85-89.
Повний текст джерелаАнотація:
The methodical methods used in the practice of the development and application of methods for the determination of chemical compounds in food products for practical instrumental studies used in conducting laboratory studies of food safety are considered. An algorithm for the development of a chromatography-mass spectrometric technique for the determination of one of the group of highly toxic, carcinogenic N-nitrosamines (N-nitrosodimethylamine, N-nitrosomethylethylamine, N-nitrosodiethylamine, N-nitrosopyrrolidineamin, N-nitrosomorpholinamine, N-nitrosodipropylamine, N- nitrosopiperidinamine N-nitrosoperidineamine and N-nitrosodiphenylamine in homogenized canned meat and meat products (canned meat) is supposed. The algorithm included experimental development of chromium parameters of chromatography-mass spectrometric determination of an analyte, the selection of optimum conditions of sample preparation of samples of canned meat to minimize the influence of the matrix: the transesterification reaction of fatty acids, organic solvent extraction, solid phase extraction, study of extraction completeness by means of the method “introduced - found”, establishment of metrological characteristics of the process of the measurement. The high sensitivity and selectivity of the chromatography-mass spectrometric determination of N-nitrosodiphenylamine in canned meat samples with a lower limit of 0.0002 mg/kg and a maximum error of not more than 23% was achieved owing to the use of a set of methodical techniques - the selection of optimal chromatographic analysis conditions: capillary column series HP-FFAP 50m • 0,320 mm • 0,50 μm, temperature programming of the column: initial temperature of 50ºС, the temperature rise up to 120ºС at a speed of 8ºC/min; from 120º to 185° C at a rate of 12° C min and from 185º to 240° C at a rate of 25°C/min with exposition at a final temperature of 5 minutes; mode of operation of the mass spectrometric detector: selective ion monitoring (SIM) for three characteristic ions of the analyzed compound of 167, 168, 169 m/z. Using the reaction of transesterification of fatty acids contained in canned meat, potassium methylate, removal of the formed esters from samples of canned meat with an organic solvent (hexane), concentration of N-nitrosodiphenylamine in the aqueous layer on cartridges of an automatic solid-phase extraction system provides the extraction of N-nitrosodiphenylamine from the test samples by 99.94%. In the process of approbation of the chromatography-mass spectrometric method, the content of N-nitrosodiphenylamine in the concentration range 0.030 ± 0.011 ÷ 3.89 ± 0.83 mg/kg was found in samples of homogenized canned food meat and meat products (canned meat) from various manufacturers. The highest concentration of N-nitrosodiphenylamine C = 3.89 ± 0.83 mg/kg was found in the sample of canned meat «beef + chicken».
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Liu, Hua, and H. G. Worthen. "Measurement of free amino acid levels in ultrafiltrates of blood plasma by high-performance liquid chromatography with automatic pre-column derivatization." Journal of Chromatography B: Biomedical Sciences and Applications 579, no. 2 (September 1992): 215–24. http://dx.doi.org/10.1016/0378-4347(92)80385-4.
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Zheng, Hanbo, Chuansheng Zhang, Yiyi Zhang, Jiefeng Liu, Enze Zhang, Zhen Shi, Guangqi Shao, Kuikui Shi, Jing Guo, and Chaohai Zhang. "Optimization of Ethanol Detection by Automatic Headspace Method for Cellulose Insulation Aging of Oil-immersed Transformers." Polymers 12, no. 7 (July 15, 2020): 1567. http://dx.doi.org/10.3390/polym12071567.
Повний текст джерелаАнотація:
The method using ethanol to evaluate the cellulose insulation aging condition of oil-immersed transformers has been proposed. At present, the dominating method for detecting ethanol in insulating oil is to use headspace–gas-chromatography–mass-spectrometry (HS-GC-MS). However, the problem of quantitative inaccuracy will be sometimes encountered in the actual detection process due to improper instrument parameter setting and improper manual operation. In this study, as an aging marker, ethanol in transformer insulating oil was separated by using VF-624 ms capillary column. The effects of gas-chromatography–mass-spectrometry (GC-MS) optimization conditions, headspace equilibrium temperature, headspace equilibrium time and standard solution preparation method on the determination of ethanol content in oil were discussed, and optimized measures were proposed. The experimental results showed that the measurement can be more accurate under the headspace temperature of 80 °C and the headspace time of 40 min, and relative standard deviation percentage (RSD%) could reach to 4.62% under this condition. It was also pointed out that, for the preparation of standard solution, the method which controlled the sampling volume of anhydrous ethanol by microliter syringe could make the peak area of ethanol chromatogram have a better linear relationship with the standard curve. Under the similar linear range, the goodness of fitting curve without diluting process could be as high as 0.9993, while the method of preparing the stock solution and diluting stepwise to obtain the fitting curve only had a goodness of 0.9910. The method was validated by standard addition recovery test, and the recovery values obtained were between 90.3% and 95.8%. The optimized method is of great significance for the measurement of ethanol dissolved in insulating oil.
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Adiukwu, Paul Chukwuemeka, and MO Tebogo. "Chromatography and mass spectroscopy analysis of bioactive principles from Vernonia amygdalina leaf aqueous extract." African Journal of Food, Agriculture, Nutrition and Development 21, no. 103 (September 27, 2021): 18501–17. http://dx.doi.org/10.18697/ajfand.103.19720.
Повний текст джерелаАнотація:
Application of medicinal plants in managing disease conditions is a practice as old as mankind. Its use in today’s healthcare has increased astronomically when compared to any other era. National policies, which integrate herbal products in healthcare systems, and the increasing presence of herbal clinics have become the order in many countries. Despite the ease of accessibility and affordability, the use of products from medicinal plants as phyto-medicines is threatened by the inability to maximize the benefits. This is due to inadequate qualitative and quantitative data necessary for proper application and regulation. Vernonia amygdalina, a herb widely used by ethnics in diverse forms of health management, is one such medicinal plant. This study was designed to determine referenceable values for the ethno formulation of the herb which is usually prepared as the aqueous extract of the leaf. Standard techniques and procedures were employed for this study. Fractionation of the extract was carried out using facilitated column chromatography. Pure principles of fractionates were separated with gas chromatography and identified using hyphenated mass spectrometer based on their relative abundance. The obtained chromatogram and spectra of principles were elucidated by relating data to the Mass Spectral Database with Automatic Mass Spectra Deconvolution & Identification System (AMDIS). Preliminary screening of extract indicated the absence of quinine but presence of alkaloids, tannins and saponins. Aqueous extraction produced 18 % (w/w) yield. The accelerated column chromatography produced a yield in the ratio of four to six to nine for the chloroform, chloroform/methanol and methanol effluents, respectively. Data obtained from the AMDIS elucidation showed the presence of eleven principles, which includes 1, 2, 3, 4-Butanetetrol; 1, 2-Benzenediol; and Caprolactam among others. Some of the properties and bioactivities of these principles have been reported in previous literature. Findings suggest that bioactivity common with some of these principles is consistent with previous literature on the use of the herb, and demonstrates reasons for the folkloric application.
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Sommerfeld-Klatta, Karina, Barbara Zielińska-Psuja, Marta Karaźniewcz-Łada, and Franciszek K. Główka. "New Methods Used in Pharmacokinetics and Therapeutic Monitoring of the First and Newer Generations of Antiepileptic Drugs (AEDs)." Molecules 25, no. 21 (November 2, 2020): 5083. http://dx.doi.org/10.3390/molecules25215083.
Повний текст джерелаАнотація:
The review presents data from the last few years on bioanalytical methods used in therapeutic drug monitoring (TDM) of the 1st–3rd generation and the newest antiepileptic drug (AEDs) cenobamate in patients with various forms of seizures. Chemical classification, structure, mechanism of action, pharmacokinetic data and therapeutic ranges for total and free fractions and interactions were collected. The primary data on bioanalytical methods for AEDs determination included biological matrices, sample preparation, dried blood spot (DBS) analysis, column resolution, detection method, validation parameters, and clinical utility. In conclusion, the most frequently described method used in AED analysis is the LC-based technique (HPLC, UHPLC, USLC) combined with highly sensitive mass detection or fluorescence detection. However, less sensitive UV is also used. Capillary electrophoresis and gas chromatography have been rarely applied. Besides the precipitation of proteins or LLE, an automatic SPE is often a sample preparation method. Derivatization was also indicated to improve sensitivity and automate the analysis. The usefulness of the methods for TDM was also highlighted.
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Herold, C. D., K. Andree, D. A. Herold, and R. A. Felder. "Robotic chromatography: development and evaluation of automated instrumentation for assay of glycohemoglobin." Clinical Chemistry 39, no. 1 (January 1, 1993): 143–47. http://dx.doi.org/10.1093/clinchem/39.1.143.
Повний текст джерелаАнотація:
Abstract The measurement of glycohemoglobin (GHb) by boronate affinity chromatography is useful in monitoring long-term glucose control in diabetic subjects. The inherent disadvantage of this method is the hands-on time required because the hemoglobin fractions are separated on individual disposable columns. To overcome this disadvantage, we have programmed a Hamilton Microlab 2200 automated pipetting cartesian robot to complete the procedure, from the aspiration of blood from the sample-collection tube to the transfer of the separated hemoglobin fractions to a microtiter plate for absorbance measurement. This automated robotic system can analyze 96 specimens, including patients' samples and control material, in approximately 3 h. The precision (CV) of the method ranged from 1.6% to 3.5% within-run and from 2.7% to 3.5% day-to-day. The results correlated with those obtained with the Accuflex semiautomated robot, which used the identical disposable column, and those obtained with a Primus high-performance liquid chromatograph, which used a regenerated microparticle column. Automation of the GHb procedure allowed improved throughput, reduced labor cost, improved precision, and offered greater laboratory safety.
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Grate, J. W., M. J. O'Hara, A. F. Farawila, R. M. Ozanich, and S. L. Owsley. "Automation of column-based radiochemical separations: a comparison of fluidic, robotic, and hybrid architectures." Proceedings in Radiochemistry 1, no. 1 (September 1, 2011): 13–19. http://dx.doi.org/10.1524/rcpr.2011.0002.
Повний текст джерелаАнотація:
AbstractTwo automated systems have been developed to perform column-based radiochemical separation procedures. These new systems are compared with past fluidic column separation architectures, with emphasis on using disposable components so that no sample contacts any surface that any other sample has contacted, and setting up samples and columns in parallel for subsequent automated processing. In the first new approach, a general purpose liquid handling robot has been modified and programmed to perform anion exchange separations using 2 mL bed columns in 6 mL plastic disposable column bodies. In the second new approach, a fluidic system has been developed to deliver clean reagents through disposable manual valves to six disposable columns, with a mechanized fraction collector that positions one of four rows of six vials below the columns. The samples are delivered to each column via a manual 3-port disposable valve from disposable syringes. This second approach, a hybrid of fluidic and mechanized components, is a simpler more efficient approach for performing anion exchange procedures for the recovery and purification of plutonium from samples. The automation architectures described can also be adapted to column-based extraction chromatography separations.
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ADACHI, Kozo, Noriko KATSURA, Yusuke NOMURA, Akinobu ARIKAWA, Masakazu HIDAKA, and Toshihisa ONIMARU. "Serum Vitamin A and Vitamin E in Japanese Black Fattening Cattle in Miyazaki Prefecture as Determined by Automatic Column-Switching High Performance Liquid Chromatography." Journal of Veterinary Medical Science 58, no. 5 (1996): 461–64. http://dx.doi.org/10.1292/jvms.58.461.
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Dyer, Randolph H. "Determination of Ethyl Carbamate (Urethane) in Alcoholic Beverages Using Capillary Gas Chromatography with Thermal Energy Analyzer Detection: Collaborative Study." Journal of AOAC INTERNATIONAL 77, no. 1 (January 1, 1994): 64–67. http://dx.doi.org/10.1093/jaoac/77.1.64.
Повний текст джерелаАнотація:
Abstract A gas chromatographic (GC) procedure for the determination of ethyl carbamate (urethane) in distilled spirits and wines using a thermal energy analyzer (TEA) system was collaboratively studied by 5 laboratories. Distilled spirits such as whiskey, brandy, gin, rum, and vodka containing low solids can be injected directly into the GC system without extraction. Liqueurs require extraction. Wine, beer, sake, and similar samples containing significant solids or other interferences are extracted prior to injection. The sample is analyzed by GC/TEA operating in the nitrogen mode with capillary column capability (30 m × 0.53 mm) and automatic injection. Helium is the carrier gas. The GC system is calibrated with a 100 ppb standard, followed by the samples. The concentration of ethyl carbamate is determined by multiplying peak area ratios by the concentration of the standard. For the distilled spirits, the recovery averaged 92%. The within-labora-tory repeatability (RSDr) ranged from 4.3 to 12.5%, with overall average of 8.0%, and reproducibility (RSDR) varied from 4.8 to 22.0%, with an overall average of 17.4%. For the wines, the recovery averaged 85%, and the RSDr ranged from 8.9 to 42.8%, with an overall average of 34.4%. The method has been adopted first action by AOAC INTERNATIONAL.
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Le Boucher, Jacques, Christelle Charret, Colette Coudray-Lucas, Jacqueline Giboudeau, and Luc Cynober. "Amino acid determination in biological fluids by automated ion-exchange chromatography: performance of Hitachi L-8500A." Clinical Chemistry 43, no. 8 (August 1, 1997): 1421–28. http://dx.doi.org/10.1093/clinchem/43.8.1421.
Повний текст джерелаАнотація:
Abstract The Hitachi L-8500A is a newly available apparatus for amino acid (AA)analysis that allows automatic on-line mixing of the ninhydrin reagent. The within-run precision (human plasma pools at three different concentrations) showed CVs <3.8% except for the lowest concentration of citrulline (4.4%), Tyr (4.5%), and α-aminobutyric acid (7.6%), and for the intermediate concentration of Asp (8.7%). Between-run precision (CV) was <3.1% for 17 AAs and <8.0% for 24 of 25 AAs (CV Asp = 12.0%). For retention times, within-run precision was <0.4% and between-run precision <1.8%. Excellent relations were found between the results from the Hitachi L-8500A and the widely used Beckman 6300 analyzer (0.929≤ r ≤0.999). The detection was still linear at 5 μmol/L except for Pro and hydroxyproline (20 μmol/L). The upper limit was at least 2500 μmol/L for 13 AAs and at least 1000 μmol/L for 27 of 29 AAs (anserine = 500, Val = 600 μmol/L). Values from 100 human plasma samples agreed with previously published data. We conclude that the results obtained with the Hitachi L-8500A are satisfactory when compared with those of other AA analyzers utilizing the same method. Furthermore, the Hitachi L-8500A displays several advantages including programming flexibility, microsample capacity, low noise plotting, ammonia filtering, and manual repacking of the analytical column.
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Mcneal, Timothy P., and Henry C. Hollifield. "Quantitative Multiresidue Analyses for Volatile Organics in Water and Milk, Using a Fused Silica Open-Tubular Wide-Bore Capillary Column and Automated Headspace Gas Chromatography." Journal of AOAC INTERNATIONAL 73, no. 2 (March 1, 1990): 328–31. http://dx.doi.org/10.1093/jaoac/73.2.328.
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Abstract A modified multiresidue capillary gas chromatographic (GC) procedure has been developed using automated headspace sampling and a wide-bore fused silica open-tubular (FSOT) capillary column for the determination of volatiles in water and milk. Compounds are quantltated by the method of standard additions. An IBM System 9000 computer with the CAPMC3 chromatographic applications package and a BASIC linear regression program are used for data reduction. Data are presented for solutions prepared by fortifying water and milk with volatile solvents such as acetone, methyl ethyl ketone, benzene, methylene chloride, and chloroform, which are commonly used in the manufacture of packaging materials and adheslves. The wide-bore FSOT capillary columns showed dramatically improved detection for certain compounds, compared with normal-bore capillary GC columns. Data presented for various chemicals demonstrate the improved limits of detection from the use of automated headspace gas chromatography with wide-bore capillary columns and flame ionization detection.
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Worthen, H. G., and H. Liu. "Automatic Pre-Column Derivatization and Reversed-Phase High Performance Liquid Chromatography of Primary and Secondary Amino Acids in Plasma with Photo-Diode Array and Fluorescence Detection." Journal of Liquid Chromatography 15, no. 18 (December 1992): 3323–41. http://dx.doi.org/10.1080/10826079208020887.
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Bohdan, T. V., D. A. Pliskevich, V. V. Bohdan, Y. O. Моshkovska, and O. V. Savchenko. "Correction of imbalance of essentialaminoacids of blood plasma in Patients with stableangina." Likarska sprava, no. 3-4 (June 30, 2021): 36–41. http://dx.doi.org/10.31640/jvd.3-4.2021(4).
Повний текст джерелаАнотація:
Introduction. Ischemic heart disease is the leading nosology calunit in the structure of cardiovascular diseases interms of disability and mortality among the population of Ukraine. The purpose. To improve the treatment of patients with stable angina by studying the effect of L-arginine on the balance of essential amino acids in blood plasma. Material and methods. It was examined 85 patients with stable angina. They were divided into two groups: group Ipatients received antianginal basic therapy, group II patients received basic antianginal therapy and L-arginine. The amino acid spectrum of patients' blood plasma was studied by ion-exchange liquid column chromatography, using an automatic amino acid analyzer T-339 Microtechna (Czech Republic, Prague). Results and discussion. In patients with stable angina who received basic therapy and L-arginine, in contrast to patients who received only basic therapy, plasma levels of arginine became normalized, which probably contributes to the synthesis of NO. The level of valine, leucine and isoleucine, which provide the synthesis of acyl-CoA and succinyl-CoA, became also normalized.Conclusion. Administration of L-arginine to patients with stable angina together with antianginal therapy helps to correct plasma amino acid imbalances, which is likely to effectively affect the course of the disease and prognosis.
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Alvarez, Covadonga, and Irving W. Wainer. "Development of an automatic solid phase extraction and liquid chromatography mass spectrometry method by using a monolithic column for the analysis of Cyclosporin A in human plasma." Talanta 79, no. 2 (July 15, 2009): 280–83. http://dx.doi.org/10.1016/j.talanta.2009.03.054.
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Hastini, Sri. "PRODUCTION OF 11 C-METHIONINE BY CYCLOTRON AVF JAERI." Indonesian Journal of Chemistry 2, no. 1 (June 5, 2010): 41–47. http://dx.doi.org/10.22146/ijc.21931.
Повний текст джерелаАнотація:
At the Takasaki-site of JAERI, an AVF cyclotron has been constructed for advanced radiation technology research. The cyclotron produces extracted beams particularly light and heavy ions of proton as well as deutron. Target chamber is available for production of 11CO2 a positron emitter radioisotope, by bombardment of proton from nitrogen gas as a target, by 14 N (p,a) 11C reaction. The use of incident energy on target was estimated to be 11 MeV for primary proton energy of 20 MeV and the beam current was 0,1 m A and the irradiation time was 10 minutes for production of 11CO2 and the yield was about 30 MBq (EOB)and for irradiation time 15 minutes and the beam current was 1 mA for production of 11C-Methionine, the yield was about 70 MBq (EOB). Remotely operated automatic and semiautomatic processing systems are used for the production of the 11 C-Methionine agent and the radiochemical purity of the product obtained was determined by High Performance Liquid Chromatography (HPLC) with cation exchange column was LC 10 AD MERCK LICHROSPHER 100 RP-18 and the mobile phase was 10 mM ammonium phormmate, the mean of retention time was 1,815 minutes and the radiochemical purity to be more than 90 %. The product was used for plant studies and visualized by PETIS (Positron Emission Tracer Imaging System) Keywords: cyclotron, Positron emitter, 11C-Methionine.
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Bogdan, T. V., V. O. Onishchenko, V. V. Bogdan, and O. V. Savchenko. "The effect of L-arginine on the balance of essential amino acids in plasma of the patients with stable angina." Likarska sprava, no. 7-8 (December 30, 2020): 25–30. http://dx.doi.org/10.31640/jvd.7-8.2020(3).
Повний текст джерелаАнотація:
Background. Despite the significant achievements of clinical medicine in the prevention, diagnosis and treatment of coronary heart disease, the levels of morbidity, disability and mortality among the population of Ukraine from this pathology remain consistently high. The purpose. To improve the treatment of patients with stable angina by studying the effect of L-arginine on the balance of essential amino acids in blood plasma. Material and methods. It was examined 67 patients with stable angina. They were divided into two groups: group Ipatients received antianginal basic therapy, group II patients received basic antianginal therapy and L-arginine. The amino acid spectrum of patients' blood plasma was studied by ion-exchange liquid column chromatography, using an automatic amino acid analyzer T-339 Microtechna (Czech Republic, Prague). Results and discussion. In patients with stable angina who received basic therapy and L-arginine, in contrast to patients who received only basic therapy, plasma levels of arginine became normalized, which probably contributes to the synthesis of NO. The level of valine, leucine and isoleucine, which provide the synthesis of acyl-CoA and succinyl-CoA, became also normalized. Conclusion. Administration of L-arginine to patients with stable angina together with antianginal therapy helps to correct plasma amino acid imbalances, which is likely to effectively affect the course of the disease and prognosis.
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Lezina, A. V., I. I. Terninko, and M. V. Krysko. "Identification and quantitative determination of arbutin in the herb of Orthilia secunda." Drug development & registration 10, no. 4 (December 25, 2021): 122–28. http://dx.doi.org/10.33380/2305-2066-2021-10-4(1)-122-128.
Повний текст джерелаАнотація:
Introduction. Orthilia secunda (L.) House is a perennial herb that grows in Europe, Siberia, Asia Minor and Central Asia. The herb of Orthilia secunda is actively used in folk medicine as a diuretic, wound-healing and anti-inflammatory agent. From literary sources it is known that this medicinal plant raw material (PRM) contains flavonoids, tannins, organic acids, vitamins, as well as simple phenols and their derivatives (arbutin and hydroquinone). The presence of arbutin is responsible for the plant's high antioxidant and anti-inflammatory properties. But the use of Orthilia secunda in official medicine is limited due to the lack of complete information on the chemical composition and criteria for standardization of this type of medicinal product.Aim. Identification and quantification of arbutin by chromatographic methods in Orthilia secunda (L.) House, harvested in various phytocenotic zones.Materials and methods. The investigated medicinal plant material – the herb of Orthilia secunda – was harvested in various phytocenotic zones: in July 2018, harvesting was carried out in the northern part of Kazakhstan (Kokshetau district), in July-August 2019 in the Perm Territory and in the Tyumen Region. Preliminary identification of arbutin and related phenols – gallic acid and hydroquinone – was carried out by high performance thin layer chromatography (HPTLC) on a CAMAG instrument with a UV cabinet (Merck HPTLC silica gel 60 F154 plates, 20 × 10), semi-automatic Linomat 5 applicator (sample application). Elution of the plates was performed in a CAMAG Automatic Developing Chamber (ADC2). Image fixation was performed on a CAMAG Scanner 3 spectrodensitometer. The quantitative determination of arbutin was carried out by the method of highperformance liquid chromatography, which was carried out on a Prominence LC-20 device (Shimadzu, Japan) according to the validated method described in the European Pharmacopoeia 10.0. Diode array detector SPD-M20A, column Intersil C18 column (250–4.6 mm, 5 μm) (Phenomenex, USA). The results were processed using the LabSolution software. The identification and quantification of arbutin was carried out in comparison with a standard solution containing a reference sample (RS) of arbutin (C = 0,025 mg/ml) and RS of hydroquinone (C = 0,0125 mg/ml).Results and discussion. HPTLC analysis made it possible to detect arbutin and gallic acid – the main product of hydrolytic degradation/ precursor of the biosynthesis of tannins of the hydrolysable group – in the herb of Orthilia secunda from different places of growth. HPLC analysis demonstrates a different chromatographic profile of Orthilia herb harvested in different phytocenotic zones. However, in all studied objects, the absence of hydroquinone and the presence of substances that can presumably be attributed to its derivatives were confirmed, which is confirmed by the visual similarity of the spectra of these compounds and the proximity of the extrema. It was found that arbutin does not belong to the marker (majority) compounds of Orthilia. Its content is low and reaches a maximum (about 0,021 %) in the herb of Orthilia secunda growing on the territory of Kazakhstan, while in the herb of Orthilia harvested in the Perm Territory arbutin was not identified. From the data obtained, it follows that the greatest accumulation of arbutin occurs in areas with a warmer and drier climate (northern part of Kazakhstan).Conclusion. HPTLC analysis of the herb Orthilia secunda allowed the identification of arbutin and gallic acid (the main precursor of tannins of the hydrolysable group). The results of HPLC analysis of Orthilia herb harvested in various phytocenotic zones suggest quantitative differences in the content of arbutin depending on the region of growth. From the experimental data, it follows that Orthilia growing in the northern part of Kazakhstan accumulates the maximum (0,021%) amount of arbutin, in comparison with the samples harvested in the Tyumen region and the Perm region. At the same time, Orthilia harvested in the Perm Territory does not accumulate arbutin. The presence of hydroquinone has not been confirmed (by HPTLC and HPLC methods); therefore, it is not justified to talk about the hydrolytic cleavage of arbutin in the process of biosynthesis or drying. However, in all studied objects there are peaks of substances with spectral characteristics like hydroquinone, which makes it possible to assume the presence of its derivatives. Therefore, it is not advisable to position arbutin as a marker compound of Orthilia secunda harvested on the territory of the Russian Federation, and to standardize raw materials for this compound.
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King, D., S. Binder, S. Dalvie, H. Essien, J. Haggas, J. Lai, and R. Patel. "AUTOMATED MULTI-COLUMN LIQUID CHROMATOGRAPHY." Therapeutic Drug Monitoring 17, no. 4 (August 1995): 392. http://dx.doi.org/10.1097/00007691-199508000-00051.
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Kabra, P. M., J. H. Wall, and P. Dimson. "Automated solid-phase extraction and liquid chromatography for assay of cyclosporine in whole blood." Clinical Chemistry 33, no. 12 (December 1, 1987): 2272–74. http://dx.doi.org/10.1093/clinchem/33.12.2272.
Повний текст джерелаАнотація:
Abstract In this rapid, precise, accurate, cost-effective, automated liquid-chromatographic procedure for determining cyclosporine in whole blood, the cyclosporine is extracted from 0.5 mL of whole blood together with 300 micrograms of cyclosporin D per liter, added as internal standard, by using an Advanced Automated Sample Processing unit. The on-line solid-phase extraction is performed on an octasilane sorbent cartridge, which is interfaced with a RP-8 guard column and an octyl analytical column, packed with 5-microns packing material. Both columns are eluted with a mobile phase containing acetonitrile/methanol/water (53/20/27 by vol) at a flow rate of 1.5 mL/min and column temperature of 70 degrees C. Absolute recovery of cyclosporine exceeded 85% and the standard curve was linear to 5000 micrograms/L. Within-run and day-to-day CVs were less than 8%. Correlation between automated and manual Bond-Elut extraction methods was excellent (r = 0.987). None of 18 drugs and four steroids tested interfered.
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Duy Hung, Nguyen, A. V. Taneva, and V. F. Novikov. "Determination of the antioxidant additive “Ionol” in transformer oil by gas chromatographic method." E3S Web of Conferences 288 (2021): 01081. http://dx.doi.org/10.1051/e3sconf/202128801081.
Повний текст джерелаАнотація:
Transformer oil is widely used in power oil-filled electrical equipment, which is an insulating and diagnostic medium. During the operation of power transformers, its operational and dielectric properties deteriorate. To increase the operating time of transformer oil, it is inhibited by an antioxidant additive, which is most often used as ionol and the ionol concentration must be constantly monitored. This control is carried out by chromatographic methods. The main problem of controlling the antioxidant additive in transformer oil is its extraction with organic extractants, which are ethyl alcohol, which contains water, which has a negative effect on the extraction process. Thus, a search for more effective extractants for the extraction of ionol from transformer oil was undertaken. The retention characteristics of individual organic extractants and antioxidant additives were determined by the method of high-performance gas-liquid chromatography using a quartz capillary column and an automated system for dosing a sample into the chromatograph under various experimental conditions. Both the isothermal mode of the experiment and under linear programming conditions of the chromatographic column have been used. The dependence of the retention characteristics of organic extractants and ionol on the temperature of analysis was established, which has a linear form.
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Vu, Ngoc Dan, Alina Vyacheslavovna Taneeva, and Vyacheslav Fedorovich Novikov. "Improvement of the gas chromatographic method for diagnosing developing defects in oil-filled electrical equipment based on the analysis of furan compounds." E3S Web of Conferences 288 (2021): 01080. http://dx.doi.org/10.1051/e3sconf/202128801080.
Повний текст джерелаАнотація:
During the operation of oil-filled electrical equipment under the influence of temperature, humidity and other negative factors, the destruction of paper insulation occurs. As a result of this destruction, furan compounds are formed, which get into the transformer oil. To identify the process of destruction of paper insulation, control of furan compounds in transformer oil is carried out by instrumental methods. Of these methods, the most widely used is gas chromatography using packed chromatographic columns, on the basis of which guidelines have been developed. To improve gas chromatographic methods for monitoring furan compounds, we used a highly efficient quartz capillary column filled with a polar stationary phase based on polyethylene glycol. The sample was injected into the injector of the chromatograph Chromos-GC1000 using an automated dosing system with a vial for 23 samples. Used transformer oil of the GK-1 brand of Almetyevsk electrical networks was taken as the object of research; The optimal retention characteristics of standard sorbates were preliminary determined, which were used as organic extractants of transformer oil and furan compounds. The effect of temperature on the process of chromatographic analysis of furfuryl alcohol and organic extractants was determined, on the basis of which it was established that the selectivity of separation is determined by the nature of intermolecular interactions in the sorbate-sorbent system, in particular, the formation of a hydrogen bond. It has been shown that the selectivity coefficient for the separation of furfuryl alcohol depends on the physicochemical nature of organic extractants, their boiling points and dipole moments and has the highest values for the analyzed pair of components: furfuryl alcohol - ethanol.
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Manousi, Natalia, and Constantinos K. Zacharis. "Automated Post-Column Sample Manipulation Prior to Detection in Liquid Chromatography: A Review of Pharmaceutical and Bioanalytical Applications." Current Analytical Chemistry 15, no. 7 (October 15, 2019): 759–75. http://dx.doi.org/10.2174/1573411015666190327170559.
Повний текст джерелаАнотація:
: Automated post-column sample manipulation is undoubtedly one of the most challenging approaches in liquid chromatography for the improvement of method selectivity and sensitivity. With the post-column analyte derivatization being the most-abundant approach approach of this category, other strategies typically comprise post-column infusion of internal standard or other reagents prior to mass spectrometric detection to enhance the ionization efficiency of the analyte or to compensate the ion suppression/enhancement. : In this review, on-line post column methodologies focused on the quality control of pharmaceuticals and biomedical applications will be presented and discussed. Emphasis will be given on the automation capabilities of such systems.
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Sannino, Anna, Paola Mambriani, Mirella Bandini, and Luciana Bolzoni. "Multiresidue Method for Determination of Organophosphorus Insecticide Residues in Fatty Processed Foods by Gel Permeation Chromatography." Journal of AOAC INTERNATIONAL 78, no. 6 (November 1, 1995): 1502–12. http://dx.doi.org/10.1093/jaoac/78.6.1502.
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Abstract A multiresidue method for quantitative determination of 39 organophosphorus compounds (parent pesticides and their major metabolites) in 7 fatty processed foods is described. Samples are extracted with methylene chloride and cleaned up by automated gel permeation chromatography with a Biobeads SX3 column and a methylene–chloridecyclohexane (15 + 85) eluant. Organophosphorus compounds are quantitated by capillary gas-liquid chromatography with flame photometric detection using OV-1701 and DB-5 columns. Average recoveries from samples fortified at 0.025–1 mg/kg ranged from 50.6% for dichlorvos to 185% for malaoxon. Determination limits were between 0.005 and 0.040 μg/mL. Results were confirmed by gas chromatography/mass spectrometry with selected-ion monitoring.
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Holtzapple, Carol K., Sandra A. Buckley, and Larry H. Stanker. "Determination of Four Fluoroquinolones in Milk by On-Line Immunoaffinity Capture Coupled with Reversed-Phase Liquid Chromatography." Journal of AOAC INTERNATIONAL 82, no. 3 (May 1, 1999): 607–13. http://dx.doi.org/10.1093/jaoac/82.3.607.
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Abstract An automated, on-line immunoaffinity extraction method was developed for the analysis of 4 fluoroquinolones in milk: ciprofloxacin, difloxacin, enrofloxacin, and sarafloxacin. This method involves analyte extraction using an immunoaffinity capture column containing anti-fluoroquinolone antibodies coupled on-line with reversed-phase column chromatography. Liquid chromatographic analyses were performed by isocratic elution using a mobile phase of 2% acetic acid-acetonitrile (85 + 15) and an Inertsil phenyl column with fluorescence detection at excitation and emission wavelengths of 278 and 444 nm, respectively. No significant interferences from the sample matrix were observed, indicating good selectivity with the immunoaffinity column. Recoveries from fortified raw milk samples (5–50 ppb of each fluoroquinolone) ranged from 72 to 90%, with standard deviations of ≤8%.
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Nurislamova, Tatyana V., Tatyana S. Ulanova, Nina A. Popova, Olga A. Maltseva, Daria Yu Subbotina, and Tatyana V. Chinko. "Chromatography-mass spectrometric determination of highly toxic and carcinogenic N-nitrosamines in water." Hygiene and sanitation 100, no. 10 (October 31, 2021): 1145–50. http://dx.doi.org/10.47470/0016-9900-2021-100-10-1145-1150.
Повний текст джерелаАнотація:
Introduction. In Russia, the current condition regarding water quality in the water bodies of the Russian Federation used for drinking purposes “continues to remain unfavourable (according to the Strategy of the Environmental Safety of the Russian Federation until 2025). It takes place primarily due to the discharges of industrial and domestic wastewater.” Thus, 19% of wastewater is discharged into water bodies without purification, 70% - insufficiently purified, and only 11% - purified to the established acceptable discharge standards. Therefore, 30-40% of the country’s population regularly uses water that does not correspond to the hygienic standards, which leads to an increased risk of morbidity among the population of Russia. This study aims to execute chromatography-mass spectrometric determination of highly toxic and carcinogenic N-nitrosamines in drinking water. Materials and methods. Within the framework of the study, we reviewed standard samples of N-nitrosamines Mix, 1X1ML, 2000 ug/ml, methanol, experimental diagrams of solid-phase extraction. The practical charts of solid-phase extraction were tested with the help of a susceptible and accurate analytical mass-spectrometric method, a gas chromatograph with a mass selective detector (MSD). An internal laboratory control was carried out according to CIS standardization recommendations 76-2014 of the State System for Ensuring Uniform Measurement to ensure the reliability of the analytical results obtained to determine N-nitrosamines in water. The quality indicators for the analysis results were experimentally established: the accuracy, correctness, precision of the analysis technique, and the methods for their assessment according to GOST R ISO 5725-2002 standards. Results. In the course of the performed experimental studies, it was found that the degree of N-nitrosamines extraction from water samples of 100 ml volume, through scavenging analytes on a carbon cartridge (Coconut 6 cm3) and using four optimal diagrams of solid-phase extraction - SPE for N-dimethyl nitrosamine, N-diethyl nitrosamine, N-dipropyl nitrosamine, N-piperidine nitrosamine was 73.9%, 90.8%, 100 and 95.4% respectively. Optimal elution scheme 4: stage 1 - conditioning the cartridge to activate it: 5 ml methylene chloride for 3 seconds, 5 ml ethyl acetate for 3 seconds, rinsing the cartridge with 5 ml water for 10 seconds. Stage 2 - adsorption of a 100 ml water sample on a 6 ml Coconut cartridge for 1 minute; stage 3 - rinsing the cartridge with 5% sodium chloride solution of 10 ml for 30 seconds; stage 4-elution of N-nitrosamines from the cartridge with methylene chloride of 3 ml for 3 min. into a test tube in position 1 of the carriage of the automatic TFE system. The method for the determination of N-nitrosamines in water is based on the concentration of the analyzed compounds of water samples on a carbon cartridge - solid-phase extraction (SPE), identification of substances by library mass spectra and retention time, quantitative determination according to the calibration graph on a high polarity capillary column HP-FFAP-50 m • 0.32 mm • 0.50 μm. Conclusion. The developed guidelines for measuring the N-nitrosamines content in the water of centralized water supply systems let us determine highly toxic compounds at the lower limit of 0.00004 μg/cm3 with an error of more than 35.0%.
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Sonbol, Heba, Hager Ebrahim, Monika Malak, Ahmed Ali, Yasmine Aboulella, Ghada Hadad, Samy Emara, and Ahmed Shawky. "Application of a Small Protein-Coated Column to Trap, Extract and Enrich Carbamazepine Directly from Human Serum for Direct Chromatographic Analysis." Separations 10, no. 2 (January 18, 2023): 71. http://dx.doi.org/10.3390/separations10020071.
Повний текст джерелаАнотація:
An automated solid phase extraction (SPE) protocol to determine carbamazepine in human serum has been developed and validated using a simple, rabid and sensitive liquid chromatography-based bio-analytical method. Extraction of carbamazepine was carried out using an on-line SPE tool of a short protein-coated (PC) ODS silica pre-column (PC-ODS-pre-column) and phosphate buffer saline (PBS) with a pH of 7.4 as an extraction solvent. There are two distinct chromatographic modes used by PC-ODS-pre-column. While carbamazepine trapping required reversed-phase liquid chromatography, proteins were extracted from serum samples using PBS by size-exclusion liquid chromatography. Then, carbamazepine was eluted from the PC-ODS-pre-column onto the quantification position using a mixture of methanol-distilled deionized water (50:50, v/v) as an eluent and ODS analytical column. At room temperature (22 ± 1 °C), carbamazepine was completely separated from the co-eluted matrix components and detected at 230 nm. Carbamazepine’s linearity was obtained at concentrations ranging from 50 to 10,000 ng/mL. With good accuracy and precision, carbamazepine recoveries in serum samples ranged from 86.14 to 97.82%. The extraction step was conducted using PBS as a safe and green extraction solvent, making this protocol both cost-effective and ecologically safe.
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Ates, Ebru, Klaus Mittendorf, and Hamide Senyuva. "An Automated Online TurboFlow™ Cleanup LC/MS/MS Method for the Determination of 11 Plasticizers in Beverages and Milk." Journal of AOAC INTERNATIONAL 96, no. 5 (September 1, 2013): 1092–100. http://dx.doi.org/10.5740/jaoacint.12-299.
Повний текст джерелаАнотація:
Abstract An automated sample preparation technique involving cleanup and analytical separation in a single operation using an online coupled TurboFlow (RP-LC system) is reported. This method eliminates time-consuming sample preparation steps that can be potential sources for cross-contamination in the analysis of plasticizers. Using TurboFlow chromatography, liquid samples were injected directly into the automated system without previous extraction or cleanup. Special cleanup columns enabled specific binding of target compounds; higher MW compounds, i.e., fats and proteins, and other matrix interferences with different chemical properties were removed to waste, prior to LC/MS/MS. Systematic stepwise method development using this new technology in the food safety area is described. Selection of optimum columns and mobile phases for loading onto the cleanup column followed by transfer onto the analytical column and MS detection are critical method parameters. The method was optimized for the assay of 10 phthalates (dimethyl, diethyl, dipropyl, butyl benzyl, diisobutyl, dicyclohexyl, dihexyl, diethylhexyl, diisononyl, and diisododecyl) and one adipate (diethylhexyl) in beverages and milk.
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Davis, J. P., M. D. Jackson, J. M. Leek, and M. Samadpour. "Sample Preparation and Analytical Considerations for the US Aflatoxin Sampling Program for Shelled Peanuts." Peanut Science 45, no. 1 (January 1, 2018): 19–31. http://dx.doi.org/10.3146/ps17-12.1.
Повний текст джерелаАнотація:
ABSTRACT The USDA aflatoxin sampling program for shelled peanuts is an important component of broader industry efforts to minimize aflatoxin occurrence in the edible market. In this program, official samples are milled with either a traditional hammer/automatic sub-sampling mill, commonly called the Dickens Mill (DM) or with a vertical cutter mill (VCM). Particle size reduction and sample homogenization are the primary objectives of sample preparation (milling) to generate subsamples which best represent the parent sample composition for downstream analysis. DM particle size reduction is limited by the 3.2 mm round hole screens internal to the mill which prevent pasting of the sample. VCM grinding converts the sample to a paste while simultaneously homogenizing the sample. Experiments demonstrate that when testing aflatoxin contaminated peanuts for equivalent sized subsamples prepared from the two mill types, made into water slurries per USDA specifications and subsequently extracted and tested for total aflatoxin per USDA specifications, VCM subsamples are more normally distributed around the sample aflatoxin mean, whereas DM subsamples are more positively skewed (median lower than mean) around the sample aflatoxin mean. Accordingly, milling official samples with a DM compared to VCM promotes more lot misclassifications. It is also demonstrated that for a given subsample after extraction and immunoaffinity column (IAC) purification, the total aflatoxin measured by either high performance liquid chromatography (HPLC) or fluorometry (both USDA approved) are practically equivalent from an accuracy perspective. There are costs (time and resources) associated with decreasing natural variation due to sampling, sample preparation and analytical testing in an aflatoxin sampling/testing program. Sample preparation is a greater source of variation compared to that of the analytical testing. Resources would be better spent replacing DM with VCM mills than converting the final analytical step from IAC-fluorometry to IAC-HPLC in an effort to best classify peanut lots for the edible market.
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Carman, Allen S., Shia S. Kuan, George M. Ware, Pesi P. Umrigar, Kenneth V. Miller, and Humberto G. Guerrero. "Robotic Automated Analysis of Foods for Aflatoxin." Journal of AOAC INTERNATIONAL 79, no. 2 (March 1, 1996): 456–64. http://dx.doi.org/10.1093/jaoac/79.2.456.
Повний текст джерелаАнотація:
Abstract Immunoaffinity column-based sample preparation procedures for determination of aflatoxins B1, B2,G1, and G2 in several food matrixes and aflatoxin M1 in milk have been automated by using flexible automation, or robotics. Components used to assemble the system were purchased commercially or developed and built in-house. A liquid-level sensor developed in-house to assist elution of the immunoaffinity column is described. After immunoaf finity column cleanup, aflatoxins are separated by reversed-phase liquid chromatography and determined by fluorescence without derivatization.Mean recoveries of aflatoxins B1, B2, and G1 added to corn and nuts at 9-36 ng/g total aflatoxins were >85% (coefficient of variation [CV] = 16%). Recoveries of aflatoxin G2 averaged 50% (CV = 28%). Recoveries of aflatoxin M1 added to milk at 0.120.50 ng/mL averaged 78% (CV = 19%). The ability of the automated system to reproduce its results is demonstrated by the fact that the CV of replicate assays is generally better than 10%. Comparability between the automated procedure and the AOAC official method is demonstrated.
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Goodman, H. O., and Z. K. Shihabi. "Automated analysis for taurine in biological fluids and tissues." Clinical Chemistry 33, no. 6 (June 1, 1987): 835–37. http://dx.doi.org/10.1093/clinchem/33.6.835.
Повний текст джерелаАнотація:
Abstract We have developed an automated method of analysis for taurine, based on incorporating an ion-exchange chromatography column into the continuous-flow AutoAnalyzer (Technicon). After removal of proteins and peptides by dialysis, taurine is selectively eluted from an ion-exchange column and reacted with o-phthaldialdehyde to yield a fluorescent compound. The advantages of this method are: full automation with no need for sample deproteinization or cleanup; sensitivity, detecting as little as 5 mumol/L; speed (20 samples per hour); and flexibility. It can be used for assaying taurine in urine, plasma, cerebrospinal fluid, and tissue homogenates. This method can be adapted for assays of other metabolites.
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Cooper, J. D. H., D. C. Turnell, B. Green, D. J. Wright, and E. J. Coombes. "Why the Assay of Serum Cystine by Protein Precipitation and Chromatography Should Be Abandoned." Annals of Clinical Biochemistry: International Journal of Laboratory Medicine 25, no. 5 (September 1988): 577–82. http://dx.doi.org/10.1177/000456328802500516.
Повний текст джерелаАнотація:
The higher bias of serum cystine estimations by a HPLC method compared with those by ion exchange techniques is shown to be largely due to differences in the sample preparation procedures of the two techniques. The ion exchange methods utilised sulphosalicylic acid serum protein precipitation and post-column ninhydrin derivatisation of cystine, whilst the high pressure liquid chromatography technique employed automated dialysis for removal of proteins and pre-column ortho-phthalaldehyde derivatisation of cystine after its conversion to cysteine and then to S-carboxymethylcysteine. Examination of these procedures showed that whilst the high pressure liquid chromatographic method accurately estimates total serum cystine and cysteine, many factors affect the precision and accuracy of serum cystine estimations using the ion exchange techniques. In particular, serum protein precipitation techniques that are currently employed for the preparation of samples for cystine analysis by ion exchange chromatography should be abandoned.
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Šmigovec Ljubič, Tina, David Pahovnik, Majda Žigon, and Ema Žagar. "Separation of Poly(styrene-block-t-butyl methacrylate) Copolymers by Various Liquid Chromatography Techniques." Scientific World Journal 2012 (2012): 1–9. http://dx.doi.org/10.1100/2012/932609.
Повний текст джерелаАнотація:
The separation of a mixture of three poly(styrene-block-t-butyl methacrylate) copolymers (PS-b-PtBMA), consisting of polystyrene (PS) blocks of similar length andt-butyl methacrylate (PtBMA) blocks of different lengths, was performed using various chromatographic techniques, that is, a gradient liquid chromatography on reversed-phase (C18 and C8) and normal-phase columns, a liquid chromatography under critical conditions for polystyrene as well as a fully automated two-dimensional liquid chromatography that separates block copolymers by chemical composition in the first dimension and by molar mass in the second dimension. The results show that a partial separation of the mixture of PS-b-PtBMA copolymers can be achieved only by gradient liquid chromatography on reversed-phase columns. The coelution of the two block copolymers is ascribed to a much shorter PtBMA block length, compared to the PS block, as well as a small difference in the length of the PtBMA block in two of these copolymers, which was confirmed by SEC-MALS and NMR spectroscopy.
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Ng, William, Jin-Rui Dai, Jacek J. Slon-Usakiewicz, Peter R. Redden, Andrew Pasternak, and Neil Reid. "Automated Multiple Ligand Screening by Frontal Affinity Chromatography–Mass Spectrometry (FAC-MS)." Journal of Biomolecular Screening 12, no. 2 (January 11, 2007): 167–74. http://dx.doi.org/10.1177/1087057106297567.
Повний текст джерелаАнотація:
High-throughput screening (HTS) efforts to discover “hits” typically rely on the large-scale parallel screening of individual compounds with attempts to screen mixtures of compounds typically and, unfortunately, giving rise to false positives and false negatives due to the nature of the HTS readout (% inhibition/activation above a defined threshold) that makes deconvolution virtually intractable. Bioaffinity screening methods have emerged as an alternative or orthogonal method to classic HTS. One of these methods, frontal affinity chromatography coupled to mass spectrometry detection (FAC-MS), although still a relatively new technique, is turning out to be a viable screening tool. However, to push FAC-MS more to the forefront as a moderate primary HTS system (or a secondary screening assay), automation needs to be addressed. An automated FAC-MS system is described using 2 columns containing immobilized hERβ, whereby while 1 column is being regenerated, the other is being used. The authors are extrapolating that in a continuous 24-h operation, the number of ligands screened could potentially approach 10,000. In addition, preliminary structure-activity relationship binding information (typically not seen in early primary HTS) can be obtained by observing the rank order of the library members in the various mixtures.