Efficiency of capillary GC columns based on phosphonium ionic liquids.

Gas chromatographic columns based on ionic liquids (ILs) are very promising since the selectivity of these columns can be tuned by both the cation and the anion chemical nature. In this paper, efficiencies of capillary columns based on four phosphonium ionic liquids were studied. The performance of seven columns containing the cation trihexyl(tetradecyl)phosphonium and the anions bromide, chloride, and bis(trifluoromethylsulfonyl)imide was evaluated by measuring the solute band broadening as a function of gas velocities at three temperatures. Hence, classical height equivalent to a theoretical plate (H) against gas velocity (u) plots corresponding to those columns were generated and the data were fitted to the Golay-Guiochon equation with the aim of seeking the optimum conditions to be operated each of them. Band broadening at practical gas velocities is mainly due to poor mass transfer properties of solutes in the (viscous) liquid phases, which limits the achieved efficiencies. These H/u plots proved to be necessary to characterize the column quality at a given temperature, to interpret the band broadening phenomena and thus, to establish the lower temperature limits and the expected plate counts at that temperature.

Determination of gas-liquid partition coefficients of several organic solutes in trihexyl (tetradecyl) phosphonium dicyanamide using capillary gas chromatography columns.

We report here gas-liquid partition constants and activity coefficients for thirty-seven volatile organic solutes in ionic liquid trihexyl(tetradecyl)phosphonium dicyanamide measured by gas-liquid chromatography using capillary columns. Four capillary columns with exactly known phase ratios were constructed and employed to measure the solute retention factors at four temperatures between 313.15 and 343.15 K. The partition coefficients were calculated from the slopes of the linear regression between solute retention factors and the reciprocal of phase ratio at a given temperature. The partition coefficients thus calculated are free from errors due to the contribution to retention from gas-liquid interphase adsorption. For these reason, reliable solute's infinite dilution activity coefficients can be obtained, as well as partition enthalpies and entropies. A thorough discussion of the uncertainties of the experimental measurements and the main advantages of the use of capillary columns to acquire the aforementioned relevant thermodynamic information was performed.

Variation of anionic moieties of dicationic ionic liquid GC stationary phases: Effect on stability and selectivity.

Dicationic ionic liquids (DILs) are more and more accepted as a new class of high temperature and polar stationary phases for gas chromatography (GC). This study deals with the effect of seven different fluorosulfonyl derivatized anions associated with two dications: 1,3-di(3-methylimidazolium)-2-methylpropane [2mC3(mim)2], and 1,3-di(3-methylimidazolium)-isobutene [i-eneC4(mim)2]. Thermophysical properties of the 14 synthesized DILs were evaluated in terms of melting point, viscosity, and thermal stability. The optimal physicochemical properties of 13 DILs allowed preparing 13 GC capillary columns. Accordingly, the polarity and selectivity of the DILs were evaluated by determining the Rohrschneider-McReynolds constants and the equivalent chain lengths of C18 fatty acid methyl esters (FAMEs). The symmetrical fluoroalkylsulfonyl and the trifluorosulfonate anions seem to produce the most polar DILs. Compared to classical polyethyleneglycol phases, the DILs showed substantially decreased retention of apolar compounds and a much stronger retention of the polar ones. Unique selectivities were observed with unsaturated FAMEs, polyaromatic hydrocarbons, and bacterial specific FAMEs. The two applications presented included a biodiesel and bacterial FAME analyses.

Determination of gas-liquid partition coefficients of several organic solutes in trihexyl(tetradecyl)phosphonium bromide using capillary gas chromatography columns.

In this paper, we report gas-liquid partition constants for thirty-five volatile organic solutes in the room temperature ionic liquid trihexyl(tetradecyl)phosphonium bromide measured by gas-liquid chromatography using capillary columns. The relative contribution of gas-liquid partition and interfacial adsorption to retention was evaluated through the use of columns with different the phase ratio. Four capillary columns with exactly known phase ratios were constructed and employed to measure the solute retention factors at four temperatures between 313.15 and 343.15K. The partition coefficients were calculated from the slopes of the linear regression between solute retention factors and the reciprocal of phase ratio at a given temperature according to the gas-liquid chromatographic theory. Gas-liquid interfacial adsorption was detected for a few solutes and it has been considered for the calculations of partition coefficient. Reliable solute's infinite dilution activity coefficients can be obtained when retention data are determined by a unique partitioning mechanism. The partial molar excess enthalpies at infinite dilution have been estimated from the dependence of experimental values of solute activity coefficients with the column temperature. A thorough discussion of the uncertainties of the experimental measurements and the main advantages of the use of capillary columns to acquire the aforementioned relevant thermodynamic information was performed.

Simultaneous Determination of 8 Residual Organic Solvents in Esomeprazole Magnesium Raw Material by Capillary GC / 中国药房

OBJECTIVE:To develop a method for simultaneous determination of 8 residual organic solvents in esomeprazole magnesium raw material,including ethanol,ethyl acetate,isopropylenzene,methanol,methylbenzene,2-phenyl-2-propanol,dichloromethane and acetonitrile.METHODS:Capillary GC was adopted.The determination was performed on HP-1 column by programmed temperature.The temperature of injector port was 220 ℃,with flame ionization detector at temperate of 250 ℃,using nitrogen as carrier gas,at the flow rate of 4.0 mL/min,with split ratio of 10∶1 and injection volume of 1 μL.RESULTS:The linear ranges of ethanol,ethyl acetate,isopropylenzene,methanol,methylbenzene,2-phenyl-2-propanol,dichloromethane and acetonitrile were 45.2-904 μg/mL(r=0.999 7),45.5-909 μg/mL(r=0.999 7),9.0-180 μg/mL(r=0.999 8),27.1-542 μg/mL(r=0.999 8),8.7-174 μg/mL(r=0.999 7),9.1-183 μg/mL(r=0.999 4),5.8-115 μg/mL(r=0.999 4),3.7-74 μg/mL(r=0.999 4),respectively.The quantitation limits were 4.5,3.0,1.4,2.7,0.6,3.0,3.9,2.8 ng,and the limits of detection were 2.2,1.0,0.4,1.4,0.3,1.0,2.0,1.4 ng,respectively.RSDs of precision tests were all lower than 2.0％.Only ethanol,methanol and methylbenzene were detected in reproducibility test,RSDs of their peak area were lower than 2.0％.The recoveries were 95.6％-104.9％ (RSD=3.3％,n=9),98.7％-102.0％ (RSD=1.1％,n=9),100.0％-103.1％ (RSD=1.1％,n=9),95.7％-104.4％ (RSD=3.0％,n=9),99.3％-104.4％ (RSD=1.7 ％,n=9),95.6％-102.2％ (RSD=2.6％,n=9),95.1％-103.3％ (RSD=2.6％,n=9),97.5％-103.3％ (RSD =1.7 ％,n =9),respectively.CONCLUSIONS:The method is sensitive and simple,and it is suitable for simultaneous determination of 8 residual organic solvents in esomerarazole magnesium raw material.

Analysis of Long-Chain Unsaturated Fatty Acids by Ionic Liquid Gas Chromatography.

Four ionic liquid (IL) columns, SLB-IL59, SLB-IL60, SLB-IL65, and SLB-IL111, were evaluated for more rapid analysis or improved resolution of long-chain methyl and ethyl esters of omega-3, omega-6, and additional positional isomeric and stereoisomeric blends of fatty acids found in fish oil, flaxseed oil, and potentially more complicated compositions. The three structurally distinct IL columns provided shorter retention times and more symmetric peak shapes for the fatty acid methyl or ethyl esters than a conventional polyethylene glycol column (PEG), resolving cis- and trans-fatty acid isomers that coeluted on the PEG column. The potential for improved resolution of fatty acid esters is important for complex food and supplement applications, where different forms of fatty acid can be incorporated. Vacuum ultraviolet detection contributed to further resolution for intricate mixtures containing cis- and trans-isomers, as exemplified in a fatty acid blend of shorter chain C18:1 esters with longer chain polyunsaturated fatty acid (PUFA) esters.

Study on capillary GC fingerprint of Guominxing Biyan Granules / 中草药

Objective: To establish the capillary GC fingerprint of Guominxing Biyan Granules and give a new method for quality control. Methods: The capillary GC was used. The ingredients of common peaks were analyzed by FID and MS. The HP-5 Phenyl Methyl Siloxane (30 m×0.32 mm, 0.25 μm) was used for capillary column. The chromatography conditions were as follows: the temperature of inlet was 200℃ in splitless sampling, the detector temperature was 250℃, the column initial temperature was 50℃, 3℃/min rose to 140℃, keeping 2 min and 10℃/min rose to 200℃, keeping 2 min. Results: Capillary GC fingerprint of volatile oil in Allergic Rhinitis Particles was established. Twelve peaks were selected as the fingerprint peaks of Allergic Rhinitis Particles. The ingredients of common peaks were designated by GC-MS. The similarity between the fingerprint of 10 batches of Allergic Rhinitis Particles Samples were 0.90. Conclusion: The established capillary GC fingerprint has desirable precision, reproducibility, and stability, and can be applied to the quality control of Guominxing Biyan Granules.

Determination of Residual Solvents in Decitabine for Injection by Capillary GC / 中国药房

OBJECTIVE:To establish a method for determining residual solvents in Decitabine for injection. METHODS:Cap-illary GC method was adopted,and the contents of residual solvents were calculated by internal standard method. The column was capillary column Agilent DB-624,flame ionization detector was used with the temperature of 280 ℃ by temperature programming, and the temperature of injector was 230 ℃,nitrogen was used as the carrier gas,flow rate was 1.5 ml/min and the split ratio was 50:1,direct injection was used,and the sample size was 1 μl. RESULTS:The linear range was 0.100 3-2.507 mg/ml for ethanol , 0.101 3-2.532 mg/ml for ether,0.102 2-2.556 mg/ml for isopropanol,0.008 3-0.207 8 mg/ml for acetonitrile,0.012 4-0.309 3 mg/ml for methylene chloride,0.014 8-0.369 4 mg/ml for tetrahydrofuran,0.078 1-1.953 mg/ml for cyclohexane,0.024 9-1.250 mg/ml for toluene and 0.017 6-0.440 9 mg/ml for N,N-dimethylformamide(r≥0.999 2);RSDs of precision and reproducibility tests were lower than 2%;recovery was 96.70%-101.60%(RSD was 0.59%-1.82%,n=9). CONCLUSIONS:The method is simple,accurate and reproducible and suitable for determining the residual solvents in Decitabine for injection.

Determination of Residual of 4 Kinds Organic Solvents in Ecabet Sodium Crude Drug by Capillary GC / 中国药房

OBJECTIVE:To establish a method for the determination of residuals of petroleum ether,ethanol,xylene and ace-tic acid in ecabet sodium crude drug. METHODS:Capillary GC was performed on the column of PGE-20M capillary column at the flow rate of 1.7 ml/min,detector was hydrogen flame ionization detector,carrier gas was nitrogen with high purity,column temper-ature was 45 ℃,maintaining 4 min,it increased to 80 ℃ with rate of 10 ℃/min,then increased to 135 ℃ with rate of 30 ℃/min,maintaining 3 min,the injection mode was direct injection,inlet temperature was 250 ℃,and the volume injection was 1.0 μl. RESULTS:The mass concentration was 0.050-1.952 g/L for petroleum ether,0.050-1.941 g/L for ethanol,0.024-0.948 g/L for xy-lene and 0.050-1.947g/L for acetic acid(r=0.999 1-0.999 7);RSDs of precision,stability and reproducibility tests were no more than 1.7%;recoveries were 99.3%-101.0%(RSD=0.7%,n=9),102.3%-103.7%(RSD=0.4%,n=9),101.2%-102.1%(RSD=0.3%,n=9) and 100.3%-102.2%(RSD=0.6%,n=9),respectively. CONCLUSIONS:The method is simple and accurate,and can be used for the control of residual of organic solvents in ecabet sodium crude drug.

Determination of Eight Residual Organic Solvents in Tolterodine Tartrate by Capillary Gas Chromatography / 中国药师

Objective:To establish a method for the determination of 8 residual organic solvents in tolterodine tartrate by capillary GC. Methods: The determination of methanol, ethanol, acetonitrile, acetone, ethyl acetate, trichloromethane and tetrahydrofuran in tolterodine tartrate dissolved in the solution of N, N-dimethylformamide-water ( 1∶ 4 ) was carried out on a CP-sil 5CB ( 60. 0 m × 0. 32 mm,5μm)column. The inlet temperature was 200℃ and the FID detector temperature was 250℃. The flow rate of carrier gas was 1. 2 ml·min-1 . The column temperature was 120℃. The headspace vial temperature was 85℃ and the time was 30min. The determina-tion of pyridine in tolterodine tartrate dissolved in the solution of dimethylsulfoxide-sodium hydroxide (17∶13) was carried out on an HP-1(30. 0 m × 0. 53 mm,5 μm) column. The inlet temperature was 220℃ and the FID detector temperature was 250℃. The column tem-perature was 80℃. The flow rate of carrier gas was 3. 0 ml·min-1 . The headspace vial temperature was 85℃ and the time was 30 min. Results:All peaks could be separated from each other under the chromatographic conditions. The linearity of the eight solvents was falrly good (r>0. 999). The average recovery was ranged from 86. 0% to 100. 2% with RSD of 1. 7%-3. 5% (n=9). The limit of detection was 0. 63, 0. 43, 0. 30, 0. 18, 0. 079, 0. 36, 0. 18 and 0. 89 μg·ml-1 , respectively. Conclusion:The methods can be applied in the determination of the eight residual organic solvents in tolterodine tartrate.

Gas chromatography for in situ analysis of a cometary nucleus V. Study of capillary columns' robustness submitted to long-term reduced environmental pressure conditions.

With the European Space Agency's Rosetta space mission to comet 67P/Churyumov-Gerasimenko, a gas chromatograph, part of the COmetary Sampling And Composition (COSAC) experiment, travelled for about 10 years in the interplanetary medium before operating at the surface of the cometary nucleus in November 2014. During its journey in space, the instrument was exposed to the constraining conditions of the interplanetary medium, including reduced environmental pressures. In order to estimate the potential influence of this severe condition on the chromatographic capillary columns, their stationary phase and the subsequent separation capability, a set of flight spare columns were kept under reduced environmental pressure in the laboratory for the same duration as the probe sent to the comet. The columns' analytical performances were evaluated recently and compared to the original ones obtained just before the launch of the Rosetta probe. The results presented here show that the chromatographic performances of the spare chromatographic columns were not altered in time. From this result, it can be expected that the flight instrument will perform nominally for the analysis of the first cometary nucleus sample to be collected ever, and that the preparation of the interpretation of the data to be taken at the cometary surface nucleus can be done through calibration of these spare columns, and other spare components of the instrument.

GC separation of enantiomers of alkyl esters of 2-bromo substituted carboxylic acids enantiomers on 6-TBDMS-2,3-di-alkyl- ß- and γ-cyclodextrin stationary phases.

The gas chromatographic separation of enantiomers of 2-Br carboxylic acid derivatives was studied on four different 6-TBDMS-2,3-di-O-alkyl- ß- and -γ-CD stationary phases. The differences in thermodynamic data {ΔH and -ΔS} for the 15 structurally related racemates were evaluated. The influence of structure differences in the alkyl substituents covalently attached to the stereogenic carbon atom, as well as in the ester group of the homologous analytes, and the selectivity of modified ß- and γ- cyclodextrin derivatives was studied in detail. The cyclodextrin cavity size, as well as elongation of alkyl substituents in positions 2 and 3 of 6-TBDMS-ß-CD, also affected their selectivity. The quality of enantiomeric separations is influenced mainly by alkyl chains of the ester group of the molecule and this appears to be independent of the CD stationary phase used. In some cases the separations occur as the result of external adsorption rather than inclusion complexations with the chiral selector. It was found that the temperature dependencies of the selectivity factor were nonlinear.

Determination of 8 Residual Organic Solvents in Spironolactone by Capillary GC / 中国药师

Objective:To establish a determination method for 8 residual organic solvents in spironolactone by capillary GC. Methods:The determination of methanol, ethanol, acetone and tetrahydrofuran in spironolactone dissolved in dimethyl sulfoxide was carried out on a DB-624 column. The inlet temperature was 200℃ and the FID detector temperature was 250℃. The constant pressure was 2. 5psi. The column temperature was raised by program. The vial temperature was 85℃ and the time was 30min. The determination of triethylamine, pyridine, N,N-dimethylformamide and dimethyl sulfoxide in spironolactone dissolved in chloroform was carried out on an HP-1 column. The inlet temperature was 220℃ and the FID detector temperature was 250℃. The column temperature was raised by program. The flow rate of carrier gas was 3. 0ml·min-1. Results: All peaks could be separated from each other with promising resolution. The linearity of the eight solvents was fairly good(r > 0. 999). The average recovery ranged from 90. 9%-94. 3% with RSD of 1. 1%-3. 3% (n = 9). The limit of detection for methanol, ethanol, acetone, tetrahydrofuran, triethylamine, pyridine, N,N-dimethylformamide and dimethyl sulfoxide was 0. 60, 0. 67, 0. 20, 0. 15, 0. 64, 0. 36, 0. 89 and 0. 82 μg · ml-1 , respectively. Conclusion: The methods can be applied in the determination of 8 residual organic solvents in spironolactone.

Determination of Residual Organic Solvents in Paclitaxel by Capillary GC / 中国药师

Objective:To establish a capillary GC method for the determination of residual organic solvents in paclitaxel. Meth-ods:The standard solution and test solution was respectively injected into an HP-INNOWAX sillica capillary column by headspace in-jection. The chromatograms were recorded with an FID. The injection port and detector temperature was 250℃ and 300℃, respective-ly, the initial column temperature was kept at 35℃ for 5 min, and then was risen to 260℃ at the rate of 25℃/min. Results:The four residual organic solvents could be separated completely. The resolution and sensitivity were acceptable. Conclusion: The method is proved to be simple, rapid, sensitive and reliable, and can be used in the determination of residual organic solvents in paclitaxel.

Optimization of programmed-temperature vaporization injection preparative capillary GC for compound specific radiocarbon analysis.

Preparative capillary GC (PCGC) is a powerful tool for the separation and purification of compounds from any complex matrix, which can be used for compound-specific radiocarbon analysis. However, the effect of PCGC parameters on the trapping efficiency is not well understood. Here, we present a comprehensive study on the optimization of parameters based on 11 reference compounds with different physicochemical properties. Under the optimum conditions, the trapping efficiencies of these 11 compounds (including high-boiling-point n-hentriacontane and methyl lignocerate) are about 80% (60-89%). The isolation of target compounds from standard solutions, plant and soil samples demonstrates that our optimized method is applicable for different classes of compounds including n-alkanes, fatty acid esters, long-chain fatty alcohol esters, polycyclic aromatic hydrocarbons (PAHs) and steranes. By injecting 25 µL in large volume injection mode, over 100 µg, high purity (>90%) target compounds are harvested within 24 h. The recovery ranges of two real samples are about 70% (59.9-83.8%) and about 83% (77.2-88.5%), respectively. Compared to previous studies, our study makes significant improvement in the recovery of PCGC, which is important for its wide application in biogeochemistry, environmental sciences, and archaeology.

Content Determination of Residual Organic Solvents in Artesunate by Capillary GC / 中国药房

OBJECTIVE:To establish capillary GC method for the determination of residual organic solvents in artesunate,such as methanol and ethyl acetate.METHODS:Capillary GC was adopted and the temperature of flame ionization detector was 250℃.RESULTS:The linear range were 0.03～0.605 mg?mL-1 for methanol(r=0.999 8) and 0.05～1.002 mg?mL-1 for ethyl acetate(r=0.999 7).The average recovery rates were 98.7% for methanol(RSD=3.0%) and 99.1% for ethyl acetate(RSD=2.1%).Only the ethyl acetate was detected in samples.CONCLUSION:Established method is simple and accurate for the content determination of residual organic solvents in artesunate.

Determination of residual solvents in protopanaxdiol by CGC / 中成药

AIM: To establish a method for detecting the residual solvents in protopanaxdiol. METHODS: Capillary GC with HP-PLOT-Q column (30 m ? 0. 53 mm ? 1. 0 ?m) was used to determine residual in protopanaxdiol. N,N-dimethyl-acetamide as solvent media,FID detector and nitrogen as the carrier gas. RESULTS: There was a good linearity at the experimental concentration (r = 0. 999 96-0. 999 99),the RSD of precision was less than 6. 0 % . The spotting recovery of the 3 residul,including methol,ethyl acetate and n-butanol,was in the range of 98. 2%-102. 2% ,and its’RSD was 1. 1%-2. 4% . CONCLUSION: The method is simple,accurate and of high sensitivity,can be used for the determination of residual solvents in protopanaxdiol.

Determination of six components in Heiguidou Oil by capillary GC / 中成药

AIM:To develop a capillary GC method for determining six components in Heiguidou Oil,?-pinene,eucalyptol,borneol,methyl salicylate,cinnamia aldehyde and eugenol. METHODS:GC was applied to quantitative analysis. Chromatographic conditions consisted of PEG-20M(30 m?0.25 mm?0.25 ?m),flame ionization detector(FID),and programmed temperature; initiation temperature was at 80 ℃ for 7 min; the rate of temperature was 15℃/minute,final temperature was at 180 ℃ for 10 min,bypass rate was 50 ∶1. The sample dissolved in absolute alcohol. The external standard was used. RESULTS:The standard curves of conclusion ?-pinene,eucalyptol,borneol,methyl salicylate,cinnamia aldehyde and eugenol were linear within the ranges of 0.322-32.150 mg/mL,0.202 -20.215 mg/mL,0.126-12.630 mg/mL,0.633-63.290 mg/mL,0.174-17.390 mg/mL,0.633-63.290 mg/mL and 0.203-20.255 mg/mL,respectively.RSD were 0.83%,0.48%,0.48%,0.31%,and 0.53 %,respectively. CONCLUSION:The established method is accurate and it can be applied to the simulta-neous assay of six components.