Determination of Dichlofluanid Residue in Soybean by Capillary Collumns Gas Chromatography

A method for the determination of dichlofluanid residue by Capillary Collumns Gas Chromatography was established in this study.Samples were extracted with acetone and subjected to through liquid-liquid extraction with N-hexane,and then they were cleanup with column that filled with florisil,subsequently separated by Capillary Column Gas Chromatography,and the electron capture detector （ECD） was used for detection.The detection limit of this method was 0.005 mg/kg （S/N=3）,and this method was rapid,sensitive and accurate,and was applied in the determination of dichlofluanid residue in soybean.

Enantioselective Determination of R-(-)-and S-(+)-Mexiletine in Microsomal Incubates by Capillary gas Chromatography

A method for the assay of R ( ) and S (+) mexiletine in rat liver microsomal incubates was developed. The method involved extraction of mexiletine from the microsomal incubates, and formation of mexiletine diastereomeric derivatives with a chiral reagent S ( ) N trifluoroacetyl prolyl chloride. Separation and quantitation of the diastereomeric mexiletine derivatives were carried out by a capillary gas chromatographic system with flame ionization detection. The assay was linear from 5 to 500 μg/ml for each enantiomer. The average recoveries of analytical method were 93 31±5 59% and 93 10±5 11% for R ( ) and S (+) mexiletine, respectively. The limits of detection and quantitation for the method were 1 0 μg/ml and 5 0 μg/ml for the R ( ) and S (+) mexiletine isomers, respectively. The reproducibility in the assay was better than 16.5% (RSD). The method has been applied to the metabolism study of R ( ) and S (+) mexiletine in rat liver microsomal incubates.

Novel guanidinium-based ionic liquids as stationary phases for capillary gas chromatography

The present study describes guanidinium-based ionic liquids（GBILs） as stationary phases for capillary gas chromatography （CGC） and to the best of our knowledge,no related reports are available up to now.In this study,a hexaalkylguanidinium ionic liquid（DOTMG-NTf;） was synthesized and coated statically onto capillary columns.Selectivity of the stationary phase was evaluated by separating Grob test mixture,test mixture,alcohols mixture,and fatty acid methyl esters mixture,and thermal stability was investigated as well.The present study demonstrates that GBILs as CGC stationary phases exhibit satisfactory selectivity and thermal stability and have a great potential as new candidates for CGC stationary phases.

Retention behaviors of novel ionic liquid stationary phases and their selectivity for capillary gas chromatography

One chloride-terminated ionic liquid（CTIL） and two hydroxyl-terminated ionic liquids（HTILs） were synthesized and used as stationary phases for capillary gas chromatography（CGC）.Molecular interactions of these stationary phases were evaluated by Abraham solvation parameter model,indicating that the CTIL exhibits remarkably strong H-bond basicity and the HTILs possess both H-bond basicity and acidity.The molecular interactions were further confirmed by separation of a complex mixture consisting of ketones,aldehydes,esters,alcohols and aromatic compounds.It was found that the obtained solvation parameters correlate well with the chromatographic performances of the analytes in terms of elution order and resolution.The well correlated relationship between the solvation parameters and the selectivity of the CTIL and HTILs stationary phases is quite helpful in predicting and understanding the retention behaviors of different types of analytes on these stationary phases.

Selectivity of guanidinium ionic liquid for capillary gas chromatography

A guanidinium ionic liquid,N,N,N＇,N＇-tetrahexyl-N＂,N＂-dimethylguanidinium bis（trifluoromethane）sulfonylimide（THDMGNTf2）, was synthesized and used as stationary phase for capillary gas chromatography.In comparison with imidazolium ionic liquid stationary phase,the present new stationary phase exhibits quite different selectivity and behaves more like a low polar stationary phase.The guanidinium ionic liquid of THDMG-NTf2 exhibited better separation of Grab test mixture than imidazolium ionic liquid of 1-octyl-3-butylimidazolium bis（trifluoromethane）sulfonylimide（OBIM-NTf2）.Solvation parameter model was also used to evaluate the selectivity of THDMG-NTf2.Additionally,essential oil of Magnolia biondii Pamp was analyzed to further evaluate the selectivity of THDMG-NTf2 for a sample of complicated components.Satisfactory separation of the essential oil was achieved on a THDMG-NTf2 column（10 m） while using a commercial column（30 m） as reference.The present study shows that the guanidinium ionic liquid possesses novel chromatographic selectivity and has great potential for wide applications.

A novel ionic liquids grafted polysiloxane for capillary gas chromatography

A new ionic liquids grafted polysiloxane used as stationary phase for capillary gas chromatography （CGC） is described. The stationary phase of 1-vinyl-3-hexylimidazolium hexafluorophosphate anchored to polysiloxane （PMHS-[VHIm][PF6]） was synthe- sized, characterized and coated onto capillary columns by static coating. The results show that the present stationary phase exhibits a very good chromatographic resolution and selectivity for Grob test mixture and alcohols with baseline resolution and symmetry peaks. The present work suggests that novel stationary phase has a great potential for further development and application. 2009 Mei Ling Qi. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Capillary gas chromatographic determination of dimethachlon residues in fresh tobacco leaves and cut-tobacco

Simple procedures for extraction and chromatographic determination of dimethachlon residues in fresh tobacco leaves and cut-tobacco are described.The determination was carried out by capillary gas chromatography(GC) with electron capture detection(ECD) and confirmed by GC-MS.The mean recoveries and relative standard deviation(RSD) were 93.2%～112.9% and 3.5%～6.7%,respectively at levels ranging from 0.01 to 0.1 mg/kg.The limit of determination was 0.001 mg/kg.Tobacco samples in routine check were successfully analyzed using the proposed method.

Gas Chromatographic Method for Identification and Quantification of Commonly Used Residual Solvents in Pharmaceuticals Products

Background: Impurities are not expected in the final pharmaceutical products. All impurities should be regulated in both drug substances and drug products in accordance with pharmacopeias and ICH guidelines. Three different types of impurities are generally available in the pharmaceutical’s product specification: organic impurities, inorganic impurities, and residual solvents. Residual solvents are organic volatile chemicals used or generated during the manufacturing of drug substances or drug products. Purpose: The aim of this study is to develop a cost-effective gas chromatographic method for the identification and quantification of some commonly used solvents—methanol, acetone, isopropyl alcohol (IPA), methylene chloride, ethyl acetate, tetrahydrofuran (THF), benzene, toluene, and pyridine—in pharmaceutical product manufacturing. This method will be able to identify and quantify the multiple solvents within a single gas chromatographic procedure. Method: A gas chromatography (GC) equipped with a headspace sampler and a flame ionization detector, and a column DB 624, 30-meter-long × 0.32-millimeter internal diameter, 1,8 μm-thick, Brand-Agilent was used to develop this method. The initial GC oven temperature was 40°C and held for 5 minutes. It was then increase to 80˚C at a rate of 2˚C per minute, followed by a further increase to 225˚C at a rate of 30˚C per minute, with a final hold at 225˚C for 10 minutes. Nitrogen was used as a carrier gas at a flow rate of 1.20 mL per minute. Dimethyl sulfoxide (DMSO) was selected as sample solvent. Results: The developed method is precise and specific. The percent RSD for the areas of six replicate injections of this gas chromatographic method was within 10.0 and the recovery result found within 80.0% to 120.0%.

Determination of 14 Organophosphorus Pesticide Residues in Mutton by Gel Permeation Chromatography-Gas Chromatography-Mass Spectrometry(GPC-GC-MS)

[Objectives]This study was conducted to purify mutton samples by gel permeation chromatography(GPC).[Methods]Fourteen organophosphorus pesticide residues in samples were qualitatively and quantitatively analyzed by gas chromatography-mass spectrometry(GC-MS)in selective ion scanning mode(SIM).[Results]The organophosphorus pesticide standard solutions showed good linearity in the mass concentration range of 0.1-10.0μg/ml with correlation coefficients(r)not lower than 0.999,and the detection limits(S=3 N)ranged from 0.01 to 0.05 mg/kg.The average recovery values were in the range of 80.2%-99.7%,with relative standard deviations(RSDs,n=3)in the range of 1.8%-6.3%,at the addition levels of 0.5,1.0 and 2.0 mg/kg.[Conclusions]The method is simple,sensitive and accurate,and can be used for the determination of organophosphorus pesticide residues in mutton.

Synergistic Effect in Mixed Capillary Gas Chromatographic Stationap Phases Containing Heptakis(2,3,6-tri-o-pentyl)-β-cyclodextrin and Dibenzo-18-crown-6

used－silical capillary columns containing heptakis（2、3、6－tri－o－pentyl）-β-cyclodextrinand dibenzo-18-crown-6 were prepared．By studying the selectivity of mixed stationary phases forsome solute pairs.as well as comparing with the heptakis（2．3、6-tri-O-pentyl）-β-cyclodextrin and thedibenzo-18-crown-6 used as individual stationary phase、the synergistic effects were observed.These effects were affected by the column temperature．mixed ratio and linear velocity of carrier gas．

Enantiomeric Separation of S-Epichlorohydrin and R-Epichlorohydrin by Capillary Gas Chromatography with FID Detector

The aim of this study was to develop a simple and derivatization free method for the Quantification of S-Epichlorohydrin in R-Epichlorohydrin by using a gas chromatography coupled with flame ionization detector (FID). Enantiopure epichlorohydrin was a valuable epoxide key starting material for preparing optically active Rivaroxaban. The enantiomeric separations of S-Epichlorohydrin and R-Epichlorohydrin were achieved on Gamaa-Dex-225 (30 meters × 0.25 mm I.D, 0.25 μm) column with a total run time of 30 min. Nitrogen was used as a carrier gas with constant pressure 25.0 psi. The critical experimental parameters such as, column selection, flow rate, injection volume and diluent were studied and optimized. Excellent correlation coeffient between peak responses and concentrations was >0.9998. The recoveries of S-Epichlorohydrin spiked in R-Epichlorohydrin were in the range from 98.2% to 102.8%. Limit of quantitation for S-Epichlorohydrin was sufficiently lower than limits specified by ICH. The method has validated as per International Conference on Harmonization (ICH) guidelines. A precise, accurate, linear and robust Gas Chromatography method was developed for the quantification of S-Epichlorohydrin in R-Epichlorohydrin for Rivaroxaban.

CAPILLARY GAS CHROMATOGRAPHIC ANALYSES OF THE PETROLEUM HYDROCARBONS IN COASTAL SEAWATER

This study of the petroleum hydrocarbons in coastal seawater, using dichloromethane extraction withO-terphenyl and n-C20 as internal standards, and gas chromatography with silica-capillary-column showedthat the recovery of petroleum hydrocarbons reaches 87.8% and that the lowest detection limit is 0.96μg.This method is reproducible, highly accurate, and applicable for determining the petroleum hydrocarbonsin coastal seawater.

Determination Enantiomer Excess(e.e.%)of Chiral Sharpless Epoxides with β-Cyclodextrin Derivatives as Chiral Stationary Phases of Capillary Gas Chromatography

Using four β-cyclodextrin derivatives, 2,6-di-O-benzyl-3-O-heptanonyl-β-CD, 2,6-di- O-benzyl-3-O-octanonyl-β-CD, 2,3-di-O-benzyl-6-O-heptanonyl-β-CD, and 2,3-di-O-benzyl -6-O- octanonyl-β-CD, as chiral stationary phases of capillary gas chromatography （CGC）, the enantiomers of Sharpless epoxides were well separated. The enantiomer excess values （e.e.%） of some chiral Sharpless epoxides were also determined successfully using these CDs.

SIMULTANEOUS DETERMINATION OF EPHEDRINE AND ITS ANALOGUES IN URINE BY CAPILLARY GAS CHROMATOGRAPHY

A method is developed for the simultaneous determination of ephedrine,pseudoephedrine, norephedrine, norpseudoephedrine and methylephedrine in urine on a capillary column using nitrogen-phosphorus detector.Diphenylamine is used as the internal standard.Calibration graphs are linear down to 1.30ug/ml urine.

A NOVEL DERIVATIVE OF β-CYCLODEXTRIN AS CHIRAL SIATIONARY PHASE IN CAPILLARY GAS CHROMATOGRAPHY

A novel β-cyclodextrin derivative, 2, 6-di-O-butyl-3-O-acetyl-β-cyclodex- trin, was prepared and used as chiral stationary phase for capillary gas chromato- graphic resolution of enantiomers, lhe glass capillary columns with the derivative having low melting point and high thermal stability could produce more than 3000 plates per column meter and have proven to be good chlral columns to separate the enantiomers of some amino acids, derivatives of epoxy ethane and alkyl halide, etc.

ANALYSIS OF VOLATILE CONSTITUENTS OF CHINESE MEDICINAL HERBS BY FLASH DISTILLATION/CAPILLARY GAS CHROMATOGRAPHY/MASS SPECTROMETRY

In present work,the volatile constituents of Curcuma longa L.,A.lancea (Thunb.) DC.,Foeniculum vulgare Mill,and Cinnamomun cassia Presl.have been analyzed by flash distillation/capillary gas chro-matography/mass spectrometry.The results are consistent with those obtained by conventional steam distillation extraction method.The optimum condition of flash distillation has been studied.The experimental results showed that this new technique proved to be a simple,rapid and efficient tool for microanalysis of volatile constituents of Chinese medicinal herbs.

Perpentylated (2, 3, 6-Tri-O-pentyl)-β-cyclodextrin Used as Capillary Gas Chromatographic Stationary Phase Prepared by Sol-gel Technology

Capillary column preparation using perpentylated (2,3,6-tri-O-pentyl)-β-cyclodextrin asstationary phase by sol-gel technology with simplicity and rapidity is described. Multiplepreparation steps in conventional column technology were avoided. The prepared columns exhibitsatisfactory chromatographic performances and pronounced selectivity for a wide range of testsolutes, and have been successfully used for the separation of nitrotoluene, dimethoxybenzene,alcohols, alkanes, dimethylphenol and cresol isomers.

DIFFERENTIATION OF SOME YEAST SPECIES BY CAPILLARY GAS CHROMATOGRAPHIC ANALYSIS OF CELLULAR FATTY ACIDS

The cellular fatty acids from a total of 62 strains of Torulopsis glabrata (T. glabrata), Saccharomyces cerevisiae (S. cerevisiae), Rhodotorula rubra (R. rubra), Candida krusei (C. krusei), Candida albicans (C. albicans) and Candida tropicalis (C. tropicalis) were examined by capillary gas chromatography. On the basis of fatty acid composition, all strains could be differentiated as to species. These results indicate that capillary gas chromatographic analysis of cellular fatty acids is likely to be useful for rapid identification or grouping of newer isolates of yeast species.

Polysiloxane with Pendant [60]Fulleropyrrolidines as Stationary Phase for Capillary Gas Chromatography

Polysiloxane with pendant [60] fulleropyrrolidines was synthesized and used as the stationary phase for capillary gas chromatography for the first time. A preliminary investigation of its property shows that it has an excellent thermostability and a wide range of allowable operating temperature from 80 degrees C to 360 degrees C.