Articles de revues : « Column injection »

1

Kehr, Ján, et Mikuláš Chavko. « Protection, efficiency, and some practical aspects of use of CGC columns in high performance liquid chromatography ». Collection of Czechoslovak Chemical Communications 51, n^o 10 (1986) : 2091–97. http://dx.doi.org/10.1135/cccc19862091.

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Some practical adaptations of compact glass cartridge (CGC) columns and design of related components of the high-performance liquid chromatographic system are suggested; included are the design of a Teflon guard column and its filling procedure, an intra-column sample injector for on-column sample delivery or for injection into the precolumn, replacement of a contaminated packing or replenishment of packing at the top of the CGC column, a procedure for shortening the column to a desired length, and the possibility of thermostatting the column by means of a water jacket. These adaptations make it possible to increase the lifetime of the CGC column as much as five times without loss of efficiency, and to use partly damaged or imperfectly packed columns.

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2

Wylie, Philip, et Katsura Uchiyama. « Improved Gas Chromatographic Analysisof Organophosphorus Pesticides with Pulsed Splitless Injectiony ». Journal of AOAC INTERNATIONAL 79, n^o 2 (1 mars 1996) : 571–78. http://dx.doi.org/10.1093/jaoac/79.2.571.

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Abstract Gas chromatographic (GC) analysis of 6 organo-phosphorus pesticides (methamidophos, acephate, omethoate, diazinon, dimethoate, and chlorpyrifos) was performed with cool on-column, splitless, and pulsed splitless injections and with nitrogen–phos phorus or mass-selective detection. The pulsed splitless technique uses a high column flow rate during injection to sweep the sample out of the inlet rapidly, reducing analyte loss due to adsorption or thermal decomposition. After injection, the column flow rate is automatically reduced to normal values for chromatographic analysis. Pesticide recoveries for splitless and pulsed splitless injections were determined by comparison of GC peak areas with those obtained with cool on-column injection. With conventional splitless injection at a column flow rate of 5 mL/min, recoveries of acephate, omethoate, and methamidophos were only 57, 63, and 71 %, respectively. Pulsed splitless methods with very fast injection flow rates dramatically improved recoveries, with all 6 pesticides falling in the 97–102% range. Because column flow rates are much less for GC with mass spectral detection (GC/MS), recoveries with splitless injection were lower and improvements with pulsed splitless injection were less dramatic for GC/MS. When splitless injection was used, recoveries of the 6 pesticides spiked into a green bean matrix were better than those of pesticides dissolved in pure solvent, presumably because matrix compounds compete with pesticides for active sites in the inlet. By using pulsed splitless injection of solvent standards with very fast initial column flow rates, systematic analyte losses in the inlet were eliminated, making recoveries of pesticides from solvent and green bean matrix very similar.

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3

Hopper, Marvin L. « Analysis of Organochlorine Pesticide Residues Using Simultaneous Injection of Two Capillary Columns with Electron Capture and Electrolytic Conductivity Detectors ». Journal of AOAC INTERNATIONAL 74, n^o 6 (1 novembre 1991) : 974–81. http://dx.doi.org/10.1093/jaoac/74.6.974.

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Abstract A system has been developed that will allow low level screening of 31 organochlorine pesticide residues using simultaneous injection on 2 dissimilar capillary columns. An electron capture detector was attached to a DB-1701 column, and an electrolytic conductivity detector in the halogen mode was attached to a DB-5 column. Chlorinated pesticide amounts ranging from 0.05 ng for γ-BHC to 1.5 ng for decamethrin can easily be quantitated and confirmed. The system can be used in either the column programmed mode or the isothermal column mode. Good reproducibility was obtained for injections in both modes. This system can easily be retrofitted to any gas chromatograph using on column or split/splitless injectors.

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4

Watanabe, Chuichi, et Keiji Hashimoto. « Direct injection of large sample volumes into capillary columns with packed column injector ». Journal of High Resolution Chromatography 13, n^o 9 (septembre 1990) : 610–13. http://dx.doi.org/10.1002/jhrc.1240130905.

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5

Hagman, Gunnar, et Johan Roeraade. « Automated at-column injection into narrow bore capillary GC columns ». Journal of High Resolution Chromatography 14, n^o 10 (octobre 1991) : 686–88. http://dx.doi.org/10.1002/jhrc.1240141010.

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6

Ma, R., et Yan Xiao. « Seismic Retrofit and Repair of Circular Bridge Columns with Advanced Composite Materials ». Earthquake Spectra 15, n^o 4 (novembre 1999) : 747–64. http://dx.doi.org/10.1193/1.1586070.

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Experimental studies on seismic retrofit and repair of typical circular bridge columns with poor lap splice details utilizing prefabricated glass fiber reinforced polymer (FRP) composite jackets and epoxy are presented in this paper. A total of seven tests on three 1/2-scale model columns were conducted. One column was tested under “as-built” condition and the other two columns were retrofitted with prefabricated composite individual and continuous jackets respectively. The jackets were applied in the potential plastic hinge region of the column to increase its lateral confinement. Brittle failure was observed in the “as-built” model column due to the bond deterioration of lap spliced longitudinal reinforcement. This brittle failure was prevented in the retrofitted columns. The repairing of failed “as-built” column by injecting epoxy into damaged plastic region resulted in significant stiffening of the portion and increase of capacity and ductility. The second repair of the specimen using both epoxy injection and prefabricated composite jacketing effectively improved its behavior further. The results of this study indicated that dramatic improvement in ductility and energy absorption capacity of columns can be achieved using these retrofit and repair methods.

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7

Parfitt, Charles H. « Wide-Bore Capillary Gas Chromatographic Determination of Organophosphorus Pesticide Residues in Foods : Interlaboratory Trial ». Journal of AOAC INTERNATIONAL 77, n^o 1 (1 janvier 1994) : 92–101. http://dx.doi.org/10.1093/jaoac/77.1.92.

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Abstract Wide-Bore capillary columns are often used as alternatives to traditionally packed columns for gas chromatographic (GC) determination of pesticide residues in foods. Fused silica columns with cross-linked, bonded stationary phases are reproducible, rugged, and easy to use and are substantially more inert than their packed column equivalents. An interlaboratory trial was conducted in 5 U.S. Food and Drug Administration laboratories to determine the practicability of using isothermal wide-bore capillary GC as an alternative to the packed column GC systems used in AOAC Official Methods for determining pesticide residues in foods. Two wide-bore capillary columns with flame photometric detection were evaluated with respect to the following: linearity of detector response; repeatability of response for equal and unequal injection volumes of standard solutions; accuracy of quantitating pesticides in food extracts when the injection volumes or analyte concentrations of the standard solution and the food extract are different; recoveries of 23 pesticides from 5 fortified food extracts, calculated from both duplicate and single injections; and relative retention times. Before shipment, food extracts supplied to participants were fortified with pesticides after preparation and extraction of the foods by Official Method 985.22. The performance of wide-bore capillary columns with cross-linked bonded methyl silicone and methyl phenyl silicone stationary phases was equal or superior to that of the packed columns specified in the Official Method.

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8

Dadonova, Anna, Ivan Yakoviv et Valerii Kozlovskiy. « Method of protection of database management systems against sql-identifier injection attacks ». Science-based technologies 52, n^o 4 (31 décembre 2021) : 305–12. http://dx.doi.org/10.18372/2310-5461.52.16385.

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The article reviews SQL injection and SQL identifier injection attacks in database management systems, identifies their nature, the threats they pose, and the types of these attacks. A new method of protecting database management systems from SQL identifier injection attacks is also covered. Proposed solution are functions that can be added to the prepared API statements: setColumnName: uses the column name and its index as arguments and setTableName: uses the table name and its index as arguments. This method allows you to prepare operators to fill placeholders with table and column names, prevents SQL-IDIA, does not skip schema information, has no restrictions on input-based sanitation approaches. These two features help prevent database management systems from leaking confidential database information by performing a default operation when the input column or table name does not exist in the database. For example, if a column name is used in a particular function and the column name is invalid, the database management system will sort the results by the first column of the table. Only the table and column names in our advanced API were examined, as GitHub analysis showed that 96% of concatenated IDs were table and column names. In all experiments, the new setColumnName feature surpassed the implementation of dynamic whitelisting. In two experiments, the implementation of a static whitelist slightly exceeded the name function of the new set of columns. Although this special approach has little performance advantage, whitelisting approaches can add non-trivial complexity to program code and lead to erroneous results. The new setColumnName feature has successfully prevented all these attacks. Filling placeholders with column names is practical and effective compared to existing special approaches, does not create additional costs compared to the existing functions of the trained operator, and is effective against SQL identifier injection attack.

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9

Penton, Z. « Gas-chromatographic determination of ethanol in blood with 0.53-mm fused-silica open tubular columns. » Clinical Chemistry 33, n^o 11 (1 novembre 1987) : 2094–95. http://dx.doi.org/10.1093/clinchem/33.11.2094.

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Abstract Several 0.53 mm (i.d.) fused-silica open tubular columns were evaluated for the gas-chromatographic determination of ethanol and other volatiles in blood by both headspace and liquid injection. These columns offer the advantages of fused-silica technology without requiring expensive modification of the instrument for capillary. Methyl silicone columns of various lengths and film thicknesses were examined and also a polyethylene glycol column. The merits of each column are discussed and relative retention times are given.

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10

Alkhateeb, Fadi L., Taylor C. Hayward et Kevin B. Thurbide. « A novel ultrashort capillary gas chromatography method using on-column injection and detection ». Canadian Journal of Chemistry 94, n^o 4 (avril 2016) : 259–64. http://dx.doi.org/10.1139/cjc-2015-0068.

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A novel method for ultrashort capillary column gas chromatography (GC) analysis is introduced, which employs on-column injection and detection and rapid temperature programming. Using 10–20 cm long capillary columns, results showed that the method provides efficient and very rapid separations for relatively simple mixtures. Moreover, the on-column aspect of the method used here is demonstrated to avoid the extra column analyte degradation that can occur in traditional approaches to such separations. As a result, the developed method allows for the first time the GC analysis of some very large and (or) highly thermally labile analytes, such as polypeptides and drug molecules that are normally prone to decomposition. As an application, this method is further used to monitor pharmaceutical degradant formation as a function of temperature and was found to provide similar results to those obtained from conventional high-performance liquid chromatography analysis. Overall, the findings indicate that this ultrashort GC column approach could be useful in these areas and potentially others, where relatively simple GC analysis and universal flame ionization detection is desirable.

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11

Mokhtar, S. U., S. T. Chin, R. Vijayaraghavan, D. R. MacFarlane, O. H. Drummer et P. J. Marriott. « Direct ionic liquid extractant injection for volatile chemical analysis – a gas chromatography sampling technique ». Green Chemistry 17, n^o 1 (2015) : 573–81. http://dx.doi.org/10.1039/c4gc01364f.

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12

Penton, Zeldae E. « Optimization of Sample Introduction Parameters for Determinations of Pesticides by Capillary Gas Chromatography Using a Two Column, Two Detector System ». Journal of AOAC INTERNATIONAL 74, n^o 5 (1 septembre 1991) : 872–75. http://dx.doi.org/10.1093/jaoac/74.5.872.

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Abstract A study was undertaken to determine if another injection mode could be substituted for splitless Injection in the trace analysis of pesticide samples. This technique often leads to problems such as carryover, poor repeatability, and breakdown of labile pesticides. Two capillary injectors were compared: a hot splitless injector and a temperature- programmable Injector, in which the sample is introduced into a glass insert under nonvaporizing conditions. With each injector, 2 columns of different polarity were Installed and a test sample containing a variety of pesticides was split between the 2 columns immediately after introduction. The effects of changing parameters such as Injector temperature, injection speed, method of installation of the 2 columns, and method of filling the syringe were examined for splitless injection. K was concluded that optimization is more difficult with splitless injection. Additionally, a comparison of precision and discrimination data demonstrated superior performance with the nonvaporizlng temperature-programmable Injector.

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13

Porsch, B., J. Voslář, J. Rosol et V. Kubánek. « Preparative high-performance liquid chromatographic columns with an intra-column injection system ». Journal of Chromatography A 520 (novembre 1990) : 295–305. http://dx.doi.org/10.1016/0021-9673(90)85113-a.

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14

Korytár, Peter, Eva Matisová, Henrieta Lefflerová et Jaroslav Slobodník. « Large Volume Injection in Fast Gas Chromatography with On-Column Injector ». Journal of High Resolution Chromatography 23, n^o 2 (1 février 2000) : 149–55. http://dx.doi.org/10.1002/(sici)1521-4168(20000201)23:2<149 ::aid-jhrc149>3.0.co;2-6.

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15

Schmid, Rainer, et Christian Wolf. « Construction of a new “closed on-column” injector for hot “on-column” injection in capillary gas chromatography ». Fresenius' Zeitschrift für analytische Chemie 324, n^o 3-4 (janvier 1986) : 315–16. http://dx.doi.org/10.1007/bf00487956.

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16

Evans, R. Douglas, Andrei Izmer, Karima Benkhedda, Andrew Toms, Angelo Fernando et Wei Wang. « Continuous online determination of 226Ra in liquid effluents using automated column chromatography-ICP-MS ». Canadian Journal of Chemistry 93, n^o 11 (novembre 2015) : 1226–31. http://dx.doi.org/10.1139/cjc-2015-0247.

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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.

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17

Suzuki, Toshesari, Kumiko Yaguchi, Kazuo Ohnishi et Tatsunori Yamagishi. « Gas Chromatographic Detection of Tris(2-chloroethyl) and Tris(2-butoxyethyl)phosphate in Groundwater by Large-Sample-Volume Injection ». Journal of AOAC INTERNATIONAL 77, n^o 6 (1 novembre 1994) : 1647–50. http://dx.doi.org/10.1093/jaoac/77.6.1647.

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Abstract A capillary gas chromatograph equipped with a flame photometric detector (GC–FPD) for splitless injection of large sample volume was developed. The GC–FPD effectively diverted dichloromethane from the analytical column through a solvent diversion column and quantitatively retained tri(2-chloroethyl) phosphate (TCEP) and tris(2-butoxyethyl)- phosphate (TBXP) on a cold-trap column in front of the analytical column. The optimum conditions for 100 uL injections of TCEP and TBXP in dichloromethane at concentrations from 1 to 100 ng/mL were investigated. With the GC–FPD, relative standard deviations of the peak area and the retention time of the triesters injected at 10 ng/mL were less than 7.0 and 0.05%, respectively. These results were similar to those from normal splitless injection of 1 μL at 1 μg/mL in dichloromethane. A screening method for TCEP and TBXP in groundwater combined with liquid–liquid extraction with dichloromethane permitted detection at low nanogram-per-liter levels. Recoveries of TCEP and TBXP in 500 mL of groundwater were greater than 77.2 and 81.4%, respectively, each at fortified level of 10ng/L.

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Jorge, Luiz Mario de Matos, Patrícia Aparecida Polli, Douglas Junior Nicolin, Regina Maria Matos Jorge, Paulo Roberto Paraíso et Rubens Maciel Filho. « SIMULATION AND ANALYSIS OF AN INDUSTRIAL COLUMN SYSTEM OF BIOETHANOL DISTILLATION HEATED BY VAPOR DIRECT INJECTION ». Engevista 17, n^o 2 (1 janvier 2015) : 254. http://dx.doi.org/10.22409/engevista.v17i2.657.

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Most commercial process simulators have its origin at the petrochemical industry and their use in other sectors depends on testing. In this context a model of an industrial column system of bioethanol distillation heated by direct injection of vapor was developed and implemented using the simulator Aspen HYSYS, which was compared with experimental data obtained in the industrial plant. The system basically consists of four columns heated by direct vapor injection and the model of the system was developed using this approach together with the simulation blocks for columns heated by reboilers available on Aspen HYSYS. For such a task it was admitted a null termal load for the reboiler and a direct vapor stream was added in the side of the column. Overall deviations between simulated values and those measured in the distillery were 2.3 % for temperatures, 12.95 % for concentrations, and 1.07 % for bioethanol production in the industrial distillation system (IDS). The low values of the deviations obtained when comparing the data of the real process with simulated data indicate that IDS is well sized and the model implemented as well as the process simulator adopted can be used in the sugar-ethanol industry with distillation columns heated by direct injection of vapor.

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Tangerman, Albert. « Highly sensitive gas chromatographic analysis of ethanol in whole blood, serum, urine, and fecal supernatants by the direct injection method ». Clinical Chemistry 43, n^o 6 (1 juin 1997) : 1003–9. http://dx.doi.org/10.1093/clinchem/43.6.1003.

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Abstract A highly sensitive, reproducible, and rapid gas chromatographic method for ethanol determination in various biological specimens (human whole blood, serum, urine, and fecal supernatants) was developed. The method involves direct injection of the biological specimen into the gas chromatograph, without any pretreatment. Contamination of the gas chromatographic column with nonvolatile material was prevented by the use of a glass liner in the injector. This liner, which acted as a precolumn, was partly filled with small glass beads. Injection was performed in between the glass beads. More than 50 injections of the various biological specimens could be done before the liner had to be replaced by a new one. This injection technique between glass beads allows direct injection of large sample volumes up to 10 μL without disturbing the gas chromatographic separation. Injection of these large sample volumes made the method very sensitive. The detection limit for ethanol amounted to 0.1 mg/L (2 μmol/L) when using an injection volume of 5 μL. Attention has also been paid to simultaneously monitoring ethanol, methanol, acetaldehyde, and acetone in blood and urine of control subjects.

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20

Li, Yeou-Fong, et Yi-Ying Sung. « Seismic repair and rehabilitation of a shear-failure damaged circular bridge column using carbon fiber reinforced plastic jacketing ». Canadian Journal of Civil Engineering 30, n^o 5 (1 octobre 2003) : 819–29. http://dx.doi.org/10.1139/l03-042.

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In this paper, the analytical and experimental results of tests on a benchmark and a damaged circular bridge column are presented. The benchmark column is a 40% scale reinforced concrete circular bridge column damaged as a result of shear failure during a cyclic-loading test; the benchmark column was then repaired by epoxy and non-shrinkage mortar and rehabilitated by carbon fiber reinforced plastic (CFRP) after the cyclic-loading test. The benchmark bridge column is tested under a cyclic-loading test with constant axial load. The result shows that the column suffered shear failure at low displacement ductility. Non-shrinkage mortar with high-pressure epoxy injection was used to repair the damaged bridge column, and then three-layer CFRP was used to rehabilitate the shear strength of the bridge column. The test result shows that the repaired and rehabilitated column develops significantly improved hys ter etic responses at high displacement ductility. The analytical lateral force displacement relationship of the bridge columns can accurately predict the experimental result, especially in the nonlinear region.Key words: carbon fiber reinforced plastic, repair and rehabilitation, bridge column.

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Fujinaga, Takashi, et Yuping Sun. « Structural Performance of Damaged Open-Web Type SRC Beam-Columns after Retrofitting ». Sustainability 12, n^o 4 (13 février 2020) : 1381. http://dx.doi.org/10.3390/su12041381.

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The structural performance of damaged open-web type of steel encased reinforced concrete (SRC) beam-columns after retrofitting was experimentally investigated. The experimental parameters were the open-web type of the encased steel and the maximum tip displacement of the columns during the initial loading. First, each column was cyclically loaded to the targeted displacement. Subsequently, the test columns were retrofitted and reloaded. The damaged portions of each column were retrofitted with the polymer cement mortar, and the epoxy resin was injected into the cracks. The experimental results indicated that the measured stiffness of the retrofitted columns was lower than the initial ones, while the displacements experienced in each column were different. The lower stiffness might be attributed to deterioration of the concrete rigidity, low rigidity of the resin and imperfect injection of the resin. Numerical analyses were also conducted to evaluate the retrofitted column behavior. The effect of the strain hysteresis of concrete at the first loading was considered for the behavior at the second loading. The analytical results predicted the experimental behaviors fairly well, which implies the validity of the analytical methods presented in this paper for evaluating the structural performance of the retrofitted SRC columns.

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Roeraade, J. « At-column injection : An improved method for accurate sample transfer to capillary columns ». Journal of High Resolution Chromatography 8, n^o 11 (novembre 1985) : 801–2. http://dx.doi.org/10.1002/jhrc.1240081116.

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Ariny Demong, Andrew Ragai Rigit et Khairuddin Sanaullah. « Effect of Swirl Gas Injection on Bubble Characteristics in a Bubble Column ». Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 102, n^o 2 (27 février 2023) : 155–65. http://dx.doi.org/10.37934/arfmts.102.2.155165.

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Swirling gas injection is a well-known technique to improve mass transfer in bubble columns. It can be used to create small bubbles with a high surface area-to-volume ratio, which is beneficial for mass transfer. Swirl gas injection can also be used to create a more uniform bubble size distribution and improve the mixing of gas and liquid in the column. This study aims to determine the impact of swirl gas injection on bubble properties, including bubble shape, size, and velocity. A bubble detection approach has been developed for quick and precise determination of bubble size distributions in gas-liquid systems. Advanced digital image processing, including edge detection and bubble edge recognition, is used in this method. The experiment is conducted in a bubble column at a height of 57 cm and 61 cm. The column had a ring sparger and was made of Plexiglas. Tap water was used as the liquid, while air from an air compressor was utilized as the gas phase. The shape, size, population, and velocity of the bubble are measured using a high-speed digital camera. According to this study, the average bubble size reduced as the impeller speed increased, while the population of bubbles increased when the sparger rotation speed increased from 30 to 150 rpm.

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Arrendale, R. F., J. T. Stewart et R. M. Martin. « Effects of the pre-column in automated on-column injection capillary gas chromatography ». Journal of Chromatography A 518 (janvier 1990) : 307–18. http://dx.doi.org/10.1016/s0021-9673(01)93192-9.

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Yang, Defeng, Guobin Xu et Yu Duan. « Effect of Particle Size on Mechanical Property of Bio-Treated Sand Foundation ». Applied Sciences 10, n^o 22 (23 novembre 2020) : 8294. http://dx.doi.org/10.3390/app10228294.

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In the field of geotechnical engineering, microbially induced calcium precipitation technology is feasible and sustainable alternative to improve the engineering characteristics of sand foundation under different geological conditions for a long time. However, it is unclear how the effects of different sand particle sizes on the engineering characteristics of bio-treated sand column. The method of intermittent injection in batches was used to develop a series of bio-treated sand columns. The results showed that the mechanical properties of the bio-treated column improved by increasing the particle size. Low concentration of bacterial suspension and cementation reagent leads to the increase of calcium carbonate and unconfined compressive strength. Additionally, the total injection times increased, thus risking time cost. Furthermore, the increase of sand particle size was beneficial to the uniformity of the spatial distribution of calcium carbonate in the bio-treated column. The coefficient of variation was reduced by up to 52.0%. Scanning electron microscopy results confirmed that the size and uniformity of calcite crystals on the surface of sand particles were related to the concentration of cementation solution.

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Engelhardt, H., R. Klinkner et G. Schöndorf. « Post-column reaction detection and flow injection analysis ». Journal of Chromatography A 535 (décembre 1990) : 41–53. http://dx.doi.org/10.1016/s0021-9673(01)88934-2.

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Janák, Karel, Anders Colmsjö et Conny Östman. « Increased on-column injection temperature for gas chromatography ». Journal of High Resolution Chromatography 18, n^o 2 (février 1995) : 117–20. http://dx.doi.org/10.1002/jhrc.1240180211.

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Schweitzer, Jeffrey S., Bin Song, Pierre R. Leblanc, Melissa Feitosa, Bob S. Carter et Kwang-Soo Kim. « Columnar Injection for Intracerebral Cell Therapy ». Operative Neurosurgery 18, n^o 3 (19 juin 2019) : 321–28. http://dx.doi.org/10.1093/ons/opz143.

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Abstract BACKGROUND Surgical implantation of cellular grafts into the brain is of increasing importance, as stem cell-based therapies for Parkinson and other diseases continue to develop. The effect of grafting technique on development and survival of the graft has received less attention. Rate and method of graft delivery may impact the cell viability and success of these therapies. Understanding the final location of the graft with respect to the intended target location is also critical. OBJECTIVE To describe a “columnar injection” technique designed to reduce damage to host tissue and result in a column of graft material with greater surface area to volume ratio than traditional injection techniques. METHODS Using a clinically relevant model system of human embryonic stem cell-derived dopaminergic progenitors injected into athymic rat host brain, we describe a novel device that allows separate control of syringe barrel and plunger, permitting precise deposition of the contents into the cannula tract during withdrawal. Controls consist of contralateral injection using traditional techniques. Graft histology was examined at graft maturity. RESULTS Bolus grafts were centered on the injection tract but were largely proximal to the “target” location. These grafts displayed a conspicuous peripheral distribution of cells, particularly of mature dopaminergic neurons. In contrast, column injections remained centered at the intended target, contained more evenly distributed cells, and had significantly more mature dopaminergic neurons. CONCLUSION We suggest that this columnar injection technique may allow better engraftment and development of intracerebral grafts, enhancing outcomes of cell therapy, compared to fixed-point injection techniques.

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Burakham, R., et K. Grudpan. « Flow Injection and Sequential Injection On-line Pre-column Derivatization for Liquid Chromatography ». Journal of Chromatographic Science 47, n^o 8 (1 septembre 2009) : 631–35. http://dx.doi.org/10.1093/chromsci/47.8.631.

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Hinshaw, J. V., et W. Seferovic. « Programmed-temperture split-splitless injection of triglycerides : Comparison to cold on-column injection ». Journal of High Resolution Chromatography 9, n^o 2 (février 1986) : 69–72. http://dx.doi.org/10.1002/jhrc.1240090203.

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Ghazali, Nurul Aimi, T. A. T. Mohd, N. Alias, E. Yahya, M. Z. Shahruddin, A. Azizi et A. Y. Fazil. « Gas Lift Optimization of an Oil Field in Malaysia ». Advanced Materials Research 974 (juin 2014) : 367–72. http://dx.doi.org/10.4028/www.scientific.net/amr.974.367.

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Gas lift is an artificial lift method which is commonly used in offshore operation with sufficient gas sources as it consumes minimum space on the platform. Gas lift operates by injecting a high pressure gas down through the tubing casing annulus of a well and the injected gas enters the tubing through a gas lift valve installed on the tubing. Gas lift increases production by two means, density reduction of oil column inside the tubing so that the flowing bottom-hole pressure which is affected by the hydrostatic pressure of the fluid column is reduced and by providing external energy to the oil as the gas expends.Reducing the bottom-hole pressure will improve the drawdown of the well. A production well is modelled by using a production modelling program, Integrated Production Modeling (IPM) Prosper to analyze the production performance at various conditions. A base case model is developed from the production data of an actual oil field to simulate the performance of the actual well without gas lift system. Later, the gas lift is added to the model and the performance was compared with the base case model. The gas parameter was also studied to determine the optimum injection gas condition for maximum oil production. The gas injected at 1490m can be achieved by injecting the gas with 1200 psi, l300 psi or 1400 psi. However, the optimum gas injection pressure was determined to be at 1400 psi as the design shows that the required unloading stage is the least. The optimum gas injection rate was determined at 5 MMscf/d with the estimated net revenue is the highest. For injection gas gravity, the lighter gas was determined to be the optimum selection since it gives significant reduction of FBHP (Flowing Bottom Hole Pressure) with less hydrostatic pressure inside the tubing column.

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Kuznetsov, V. G., et O. A. Makarov. « PRESSURE CONTROL SYSTEM AT CEMENTATION OF WELLS ». Oil and Gas Studies, n^o 1 (1 mars 2017) : 62–67. http://dx.doi.org/10.31660/0445-0108-2017-1-62-67.

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At cementing of casing of oil and gas wells during the process of injecting of cement slurry in the casing column the slurry can move with a higher speed than it’s linear injection speed. A break of continuity of fluid flow occurs, what can lead to poor quality isolation of producing formations and shorten the effective life of the well. We need to find some technical solution to stabilize the linear velocity of the cement slurry in the column. This task can be resolved with an automated control system.

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Saleh, Shaif Mohammed Kasem, Safa Fadhel Mohammed Al-Nawi et Wafa Farooq Suleman Badulla. « STABILITY STUDY OF GENTAMICIN SULPHATE INJECTION USING HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY ». Electronic Journal of University of Aden for Basic and Applied Sciences 3, n^o 4 (31 décembre 2022) : 351–58. http://dx.doi.org/10.47372/ejua-ba.2022.4.205.

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Stability is the main quality characteristic of any drug product, it involves changes in physical, chemical and biopharmaceutical properties. The current work studied the stability of gentamicin (Gen) sulfate injection using HPLC, four samples of Gen were selected. Inj-I, Inj-II, Inj-III, and Inj-IV. The selected injections were stored at room temperature and analyzed at zero time then after three and six months. The analysis was achieved using reverse-phase chromatography with isocratic elution at a flow rate of 1.1 ml/min. Chromatography analysis was performed on the ODS (C8) column, 15× 0.45 cm, 5µm particle size, the column temperature was 30 ºC, and a manual injector with a 20 µl loop was used for the injection of the sample solution and mobile phase. The mobile phase was a mixture of methanol/water / glacial acetic acid/sodium 1-heptane sulfonate. The eluent was monitored with a UV-Detector at a wavelength of 330 nm with a flow rate of 1.1 ml/min. The results of the analysis showed that the pH values of all samples decreased slightly however, it was still within the acceptance range of USP. The influence of storage temperature on the degradation of the drug was evidenced whereas the Inj-I sample was the least degraded, while Inj-IV was the highest degraded sample. The accuracy was evaluated by the percent of recovery at three different concentrations in the range (99.38-100%), the precision of the method was satisfactory, and the values of relative standard deviation were less than 2%.

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Fehringer, Norbert V., et Stephen M. Walters. « Evaluation of Capillary Gas Chromatography for Pesticide and Industrial Chemical Residue Analysis. II. Comparison of Quantitative Results Obtained on Capillary and Packed Columns ». Journal of AOAC INTERNATIONAL 69, n^o 1 (1 janvier 1986) : 90–93. http://dx.doi.org/10.1093/jaoac/69.1.90.

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Abstract Results of pesticide and industrial chemical residue determinations, using both capillary and packed column gas chromatography (GC), in 3 Food and Drug Administration (FDA) laboratories have been compiled and compared. Samples consisted of food products collected for routine residue screening by the respective laboratories. Extracts were prepared by conventional multiresidue methodology. Capillary column systems and operating conditions were selected at the discretion of each laboratory and were therefore variable, although split/splitless injectors in the split mode were used with prescribed precautions in all cases. Packed column systems were operated as specified in the FDA Pesticide Analytical Manual (PAM). Overall correlation between the 2 systems, expressed as the average ratio of packed column result to capillary column result, was 0.99 for 120 determinations in 41 samples. The higher resolving power of the capillary systems allowed quantitation of several residues that were incompletely separated and therefore unquantifiable using the packed columns. Capillary column GC with the split injection technique, used with appropriate precautions, was found to be both reliable and advantageous for regulatory determination of pesticide and industrial chemical residues in foods and feeds.

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Shihabi, Z. K., et R. D. Dyer. « Serum Injection of the HPLC Column for Carbamazepine Assay ». Journal of Liquid Chromatography 10, n^o 11 (septembre 1987) : 2383–91. http://dx.doi.org/10.1080/01483918708068919.

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Shihabi, Z. K., R. D. Dyer et J. Scaro. « Serum Injection on the HPLC Column for Pentobarbital Assay ». Journal of Liquid Chromatography 10, n^o 4 (mars 1987) : 663–72. http://dx.doi.org/10.1080/01483918708069017.

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SATOH, IKUO, et IKUKO SAKURAI. « Use of a Laccase-Column for Flow-Injection Calorimetry ». Annals of the New York Academy of Sciences 864, n^o 1 ENZYME ENGINE (décembre 1998) : 493–96. http://dx.doi.org/10.1111/j.1749-6632.1998.tb10366.x.

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Westerlund, D. « Direct injection of plasma into column liquid chromatographic systems ». Chromatographia 24, n^o 1 (décembre 1987) : 155–64. http://dx.doi.org/10.1007/bf02688478.

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Coym, Jason W., et Thomas L. Chester. « Improving injection precision in packed-column supercritical fluid chromatography ». Journal of Separation Science 26, n^o 6-7 (1 mai 2003) : 609–13. http://dx.doi.org/10.1002/jssc.200390083.

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McCullough, Ph R., et F. Pacholec. « Simplified cool on-column injection with wide-bore capillaries ». Journal of High Resolution Chromatography 8, n^o 3 (mars 1985) : 141–42. http://dx.doi.org/10.1002/jhrc.1240080307.

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Bicchi, C., C. Frattini, G. M. Nano et A. D'Amato. « On column injection-dual channel analysis of essential oils ». Journal of High Resolution Chromatography 11, n^o 1 (janvier 1988) : 56–60. http://dx.doi.org/10.1002/jhrc.1240110115.

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Rosenblum, Laura, Thomas Hieber et Jeffrey Morgan. « Determination of Pesticides in Composite Dietary Samples by Gas Chromatography/Mass Spectrometry in the Selected Ion Monitoring Mode by Using a Temperature-Programmable Large Volume Injector with Preseparation Column ». Journal of AOAC INTERNATIONAL 84, n^o 3 (1 mai 2001) : 891–900. http://dx.doi.org/10.1093/jaoac/84.3.891.

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Abstract Use of a temperature-programmable preseparation column in the gas chromatographic (GC) injection port permits determination of a wide range of semi-volatile pesticides including organochlorines, organophosphates, triazines, and anilines in fatty composite dietary samples while reducing sample preparation time and solvent consumption. Dietary samples are mixed with diatomaceous earth and are Soxhlet-extracted with an azeotropic solution of hexane and acetone. Sample preparation uses liquid–liquid partitioning over diatomaceous earth followed by normal phase chromatography over partially deactivated alumina. The final cleanup step occurs in a preseparation column in the GC injector, which is able to perform splitless transfer of the analytes to the analytical column and purge 99% of the high molecular weight residue. Detection is performed by GC/mass spectrometry (MS) in the selected ion monitoring mode. Method detection limits were at or below 2 ng/g for 24 of 35 pesticides studied, with recovery between 70 and 125% for 27 pesticides in samples fortified at 10 ng/g. Recovery was not dependent on fat content when measured in laboratory fortified samples containing 1, 5, and 10% fat by weight. Precision over multiple injections was acceptable, with a relative standard deviation of 2.6–15% for 25 analytes.

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Berg, Jonathan D., et Brendan M. Buckley. « Rapid Measurement of Anticonvulsant Drug Concentrations in the Out-Patient Clinic, Using HPLC with Direct Injection of Plasma ». Annals of Clinical Biochemistry : International Journal of Laboratory Medicine 24, n^o 5 (septembre 1987) : 488–93. http://dx.doi.org/10.1177/000456328702400511.

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A manual column-switching technique is described for the measurement of phenytoin, phenobarbitone, carbamazepine, and carbamazepine 10,11-epoxide. The analytical system is designed to be portable for use at the out-patient clinic and comprises an isocratic pump, UV detector and injection valve, together with a preparation column. Diluted plasma or serum is injected, without pre-extraction, onto a preparation column which replaces the sample loop on the injection valve. After washing unwanted material to waste, the preparation column is switched in-line with the analytical column, where separation of analytes occurs. The precision, accuracy and carryover of this extra-laboratory system are comparable with those obtained with laboratory-based immunoassay systems. Operation of the system allows the reporting of results within 5 min of sample injection and requires no specialist skills. The technique should be of particular interest to district general hospital laboratories where workload does not justify the cost of an automated HPLC system as the total capital cost is comparable to that of a portable glucose analyser. In contrast to immunoassay systems consumable costs are minimal. The equipment is easy to transport and may be used in the out-patient department to provide an analytical service similar to that provided for the determination of prothrombin time at the anticoagulant clinic.

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Kodama, K., K. Yamanaka, T. Nakata et M. Aoyama. « Liquid-chromatographic assay of urinary vanillylmandelic acid and homovanillic acid, with clean-up by on-column injection of acetonitrile or methanol. » Clinical Chemistry 32, n^o 10 (1 octobre 1986) : 1944–47. http://dx.doi.org/10.1093/clinchem/32.10.1944.

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Abstract To separately measure vanillylmandelic acid (VMA) and homovanillic acid (HVA) in urine, the sample is diluted 10-fold with 50 mmol/L phosphoric acid, then exactly 5 microL is injected directly onto a 50 X 4.6 mm column of Nucleosil 3C18. Samples can be injected at 5-min intervals because all peaks after these compounds of interest are washed away. VMA is eluted from the column after 2.8 min with 50 mmol/L phosphate buffer, pH 2.2, and measured by electrochemical detection. All peaks eluting after VMA are washed away together, by injection of 50 microL of acetonitrile onto the column. HVA is eluted from the column after 3.3 min with a 100/10 (by vol) mixture of the phosphate buffer and acetonitrile. All later-eluting peaks are washed away together, by injection of 50 microL of methanol onto the column. Analytical recoveries of VMA and HVA were 98.5% and 100.6%, respectively; the CVs for various concentrations of either in urine were about 3%.

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Chen, Meilan, Jiasheng Yu, Mingli Ye et Weiqiang Guo. « Analysis of Ammonium in Seawater by Ion Chromatography With Single-Pump Column Switching ». Marine Technology Society Journal 51, n^o 3 (1 mai 2017) : 43–47. http://dx.doi.org/10.4031/mtsj.51.3.5.

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AbstractAn ion chromatograph single-pump column-switching system was developed for the determination of ammonium in high salt matrices. The simple system included a pump, a suppressor, two valves, two columns, a single eluent, and a conductivity detector. Using this method, both online collection and matrix elimination were achieved. Ammonium was eluted from the acceptor loop to the analytical column circularly. Under the optimized separation conditions, the method showed good linearity (r = 0.9997) in the range of 0.05‐2.0 mg/L and satisfactory repeatability (RSD < 4%, n = 6). The limit of detection was 4 μg/L (S/N = 3) with 25 μl injection. The utilization of the method was demonstrated by the analysis of seawater, with satisfactory spiked recoveries of ammonium between 98.8% and 108.7%. The result showed that the single-pump column-switching system was convenient and practical for the determination of low-level ammonium in high-salinity samples.

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Petrov, Panayot, Simon Cowen et Heidi Goenaga-Infante. « On-column internal standardisation as an alternative calibration strategy for speciation analysis : feasibility demonstration through analysis of inorganic As in rice ». Analytical Methods 13, n^o 33 (2021) : 3641–48. http://dx.doi.org/10.1039/d1ay00699a.

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On-column species-specific internal calibration, based on the injection of internal standard, which is the same as the analyte species, compensates for on-column losses, signal drift and others, and provides accurate measurements with low uncertainty.

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Maris, Christophe, Alain Laplanche, Jean Morvan et Marianne Bloquel. « Development of a Packed Precolumn for Capillary Gas Chromatographic Analysis of Amines in Acidic Aqueous Solution ». Water Science and Technology 40, n^o 6 (1 septembre 1999) : 141–48. http://dx.doi.org/10.2166/wst.1999.0283.

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This paper describes an optimization of the analysis of amines in aqueous solution. Direct injection of the acidic sample (HCl 0.12 N) is performed by the coupling of packed precolumn with a capillary column. The basic support efficiently traps residual vapors of hydrochloric acid and water at the injection time; the capillary chromatographic performance is maintained. The precolumn coupling with PoraPLOT Amines capillary column enables a separation and quantification of the lower volatile aliphatic amines (methylamine, dimethylamine, trimethylamine and ethylamine). The ammonia addition to the solution (200 ppm NH3) reduces amine adsorption in the column. The analysis repeatability is about 5% for a 50μM amine mixture and 21% for the quantification limit of 0.5 μM with a sensitive and specific nitrogen phosphor detector. The precolumn avoids using split injection (sensitivity increased). Other nitrogen compounds can be analyzed by this system: aromatic amines (aniline) and unsaturated nitrogen heterocycles (pyridine). This new technique increases the chromatographic performances in comparison with usual methods; its automation is possible.

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Ferreira, Juliana Veloso, Gerson A. Pianetti et Christian Fernandes. « BIOANALYTICAL METHOD BY COLUMN-SWITCHING WITH DIRECT INJECTION OF HUMAN PLASMA FOR DETERMINATION OF SULPHONYLUREAS ». Drug Analytical Research 3, n^o 1 (17 juillet 2019) : 16–22. http://dx.doi.org/10.22456/2527-2616.91542.

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Sulphonylureas are widely used in the treatment of Diabetes mellitus, one of the main causes of death in human population. Their determination is essential in pharmacological research and in the development of new drugs. Generally, determination of sulphonylureas in biological matrices is performed using conventional sample preparation techniques, which frequently leads to an increase of analysis time and errors. In this context, a bioanalytical method for the simultaneous determination of sulphonylureas by direct injection of human plasma was developed and optimized. An automated column-switching high performance liquid chromatographic system with a restricted access media (RAM) column coupled to a fused-core column was employed. At the first dimension, a RAM column with mobile phase of ultrapure water pH 6.0 at a flow-rate of 1.0 mL min-1 was used. The valve switching time was 3 minutes. At the second dimension, a C18 guard-column coupled to a C18 fused core column with mobile phase of acetonitrile and 10 mM phosphate buffer pH 3.0 (54:46 v/v) at a flow-rate of 0.8 mL min-1 were employed. The column switching system was performed in backflush configuration with an analyte elution time of 1 minute. Flufenamic acid was used as the internal standard. The mean plasma protein exclusion percentage by the RAM-column was 104.5%. The developed and optimized method showed to be fast and simple, allowing the direct injection of biological sample into the chromatographic system and the simultaneous determination of three sulphonylureas in only 12 minutes, including the sample treatment, separation and detection.

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Syamsuri, Syamsuri, Yustia Wulandari Mirzayanti, Zain Lillahulhaq et Achmad Bagus Hidayat. « Implementation of packed column for biogas purification as fuel for motorcycle injection systems for performance improvement ». Eastern-European Journal of Enterprise Technologies 4, n^o 1(112) (31 août 2021) : 86–93. http://dx.doi.org/10.15587/1729-4061.2021.239027.

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The use of gasoline for primary energy consumption can reduce crude oil, contained in the earth. The development of alternative fuels such as biogas and biofuel is very critical to overcoming this problem. Biogas requires purification to remove some contaminant particles that interfere with the combustion process. The packed column is generally applied to absorb and separate gas and liquid mixture. It is more efficient due to the liquid flows down the column of steam naturally without the supply of energy from outside the system. This study focuses on determining the effect of the packed column biogas purification process. Biogas is applied as an alternative fuel in spark-ignition engines (SIE). The test is carried out using a chassis dynamometer to obtain power and torque data. The use of the packed column for biogas fuel purification can produce higher performance compared to unrefined biogas. The unrefined biogas still contains impurities that can interfere with the combustion process. This condition is proven by measuring the power and torque of the vehicle on the chassis dynamometer, where the filtered biogas produces higher power and torque. Tests were carried out both using the packed column and without the packed column. Variations from speed to torque, to power, to SFC and BMEP are considered. In this study, validation is in good agreement with previous studies. Overall, the results show that the average error between using the packed column and without the packed column for torque, power, SFC and BMEP is increased by approximately 7 %. Purification of biogas using the packed column using Ca(OH)2 can bind CO2 and obtain pure methane gas with a higher heating value. In conclusion, the packed column for biogas purification as fuel for motorcycle injection systems can be applied

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Billiter, T. C., et A. K. Dandona. « Simultaneous Production of Gas Cap and Oil Column With Water Injection at the Gas/Oil Contact ». SPE Reservoir Evaluation & ; Engineering 2, n^o 05 (1 octobre 1999) : 412–19. http://dx.doi.org/10.2118/57640-pa.

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Summary The conventional way to produce an oil reservoir that has a gas cap is to produce only from the oil column while keeping the gas cap in place so that it can expand to provide pressure support. Depending upon the geometry, reservoir dip angle, and oil production rates, gas can either cone down to the oil producers or breakthrough as a front, leading to substantial increases in the gas-oil ratios of the oil producers. This paper presents a unique production methodology of simultaneously producing the gas cap and oil column while injecting water at the gas-oil contact to create a water barrier to separate the gas cap and oil column. This methodology has application in reservoirs with a low-dip angle, large gas cap, and a low residual gas saturation to water. It is demonstrated that the net present value of the project is improved if there is an immediate market for gas. Geostatistical reservoir models are used to demonstrate that the gas cap recovery is minimally impacted by heterogeneities. Introduction of the Concept The conventional way to produce an oil reservoir that has a gas cap is to produce the oil column while minimizing production from the gas cap. During the pressure depletion of the reservoir, the gas cap will expand to provide pressure or energy support. After the oil column is depleted, the gas cap is "blown down." In developing a production strategy for an oil reservoir with a large gas cap, a low-dip angle, and an available gas market, simultaneous waterflooding of the gas cap and oil column was evaluated. The water is injected at the gas-oil contact at rates high enough to overcome gravity effects and thus, the water displaces the gas up dip. In addition to providing pressure support, the created water wall separates the gas cap and the oil column regions. Since the development plan calls for the use of electrical submersible pumps (ESPs) in the oil producing wells, it is imperative to keep the gas production volumes from these oil wells at low levels so the ESPs will operate smoothly. As such, it is critical to control the downward migration of the gas cap. To maintain the reservoir pressure, water is injected not only at the gas-oil contact but also around the downdip periphery of the oil column to support the oil withdrawal rates. A simplistic representation of the simulated structure is shown in Fig. 1. This figure shows the location of the gas-oil contact, along with the location of the water injector at the gas-oil contact and of the gas cap producer. The reservoir considered in this study has a dip angle of 2°. For the purposes of illustration the dip angle has been exaggerated in Fig. 1. The horizontal distance between the injector and producer is 12,155 feet. The structural elevation difference between these two wells is 425 feet. Taking into account the density difference between the water and gas, the injected water must overcome a gravity component of 149 psi in addition to the energy required for the water to displace the gas. The possibility of injecting water at high enough rates to overcome both the gravity and displacement components is shown in this paper. The main objective of this paper is to present the concept of simultaneously producing the gas cap and oil column while injecting water at the gas-oil contact. The application of this concept for a newly discovered, offshore oil field has been studied. In this study, the majority of the effort was dedicated to theoretically proving this concept, as opposed to optimizing the number of wells and placement of wells to increase the recovery factors for oil and gas. This production methodology should be applicable to other reservoirs with similar characteristics. Partial Proof of Concept A literature survey indicated that the simultaneous production of the gas cap and oil column while injecting water at the gas-oil contact, has never been documented. However, four case histories were found in which water was injected at the gas-oil contact for the sole purpose of preventing the migration of the gas cap down structure. By preventing this migration, increased oil recoveries were realized. In these four cases, the gas cap was not produced during the depletion of the oil column. One successful application of this production methodology was to the Adena field in the Denver basin in 1965.1 By injecting water at the gas-oil contact, the operator was able to keep the producing gas-oil ratio value close to the solution gas-oil ratio value for an extended time. The ultimate oil recovery was estimated to be 47% of the original oil in place. The methodology of injecting water at the gas-oil contact was also applied in seven of the oil reservoirs of the Algyo Field in Hungary.2 These seven reservoirs are thin oil edge zones with large gas caps. The operators of this field were able to increase oil recovery by over 10% of original oil in place by using this methodology. In the Canadian oil field Kaybob South, the injection of water at the gas-oil contact was studied by Deboni and Field.3 They used numerical simulation to determine that a waterflood can be successfully implemented adjacent to a gas cap if a proper water "fence" is established between the gas cap and oil column. The authors concluded that an additional 10% of the oil in place can be recovered.

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