THE SEPARATIONS OF ENANTIOMERS OF α—SUBSTITUTED-(2—PYRIDYL)—METHYLAMINES ON A CHIRASIL-VAL CAPILLARY COLUMN

Enantiomers of a-substituted-(2-pyridyl)-methylarfdnes uere separated on SC -7 gas chromatograph with a 20m×0.25mm Chirasil-Val capIlary column,Carrier gas was nitro- gen or hydrogen.The resolution factors(ri.s) were 1.02 to 1.06.Enantiomers of pyridyl anines were separated to and near to base line.

AN EASY-TO-MAKE OZONE GENERATOR FOR THE IMMOBILIZATION OF STATIONARY PHASES IN GC CAPILLARY COLUMNS

An easy-to-make ozone generator which can be made with readily available materials is proposed. Concentration of the ozone prepared with this generator could reach that of ozone in equilibrium with oxygen. Cured with the ozone thus prepared, GC capillary columns with immobilized SE-54 phase and excellent chromatographic performance were successfully prepared.

Capillary Zone Electrophoretic Separation of Basic Proteins with Coated Columns Prepared by Sol-Gel Technology

Coated capillary columns were prepared by sol-gel technology and used in the separation of basic proteins with capillary zone electrophoresis. The results indicated that a significant decrease in protein adsorption was obtained and EOF was also diminished to zero in the pH range of 3-10.

Rapid Determination of HAAs Formation Potential of the Reaction of Humic Acid with Chlorine or Chlorine Dioxide

On the basis of gas chromatography（GC） coupled with a short capillary column and an electron capture detector （ ECD）, a simple and rapid method for the determination of five haloaceric acids （ HAAs ） in drinking water was developed by the optimization of derivation conditions and the modification of gas chromatographic program. HAAs formarion potential（HAAFP） of the reaction of humic acid with chlorine was determined via this method. The major advantages of the method are the simplicity of chromatographic temperature program and the short run time of GC. Dichloroaceric acid（DCAA） and Trichloroacetic acid（TCAA）, which were detected in the determination of HAAFP, were rapidly formed in the first 72 h of the reaction of humic acid with chlorine. HAAFP of the reaction of humic acid with chlorine increased with the increase in the concentrations of humic acid and chlorine. The average HAAFP of the reaction of humic acid with chlorine was 39.9μg/mg TOC under the experimental conditions. When the concentration of humic acid was 4 mg/L, the concentration of HAAs, which were produced in the reaction of humic acid with choline, may exceed MCL of 60μg/L HAAs as the water quality standards for urban water supply of China and the first stage of US EPA disinfecrion/disinfection by-products（D/DBP） rule; when the concentration of humic acid was 2 mg/L, the concentration of HAAs may exceed MCL of 30 μg/L HAAs for the second stage of US EPA D/DBP rule. When humic acid was reacted with chlorine dioxide, only DCAA was detected with a maximum concentration of 3.3 μg/L at a humic acid content of 5 mg/L. It was demonstrated that the substitution of chlorine dioxide for chorine may entirely or partly control the formation of HAAs and effectively reduce the health risk associated with disinfected drinking water.

Effects of Coated Capillary Column, Derivatization, and Temperature Programming on the Identification of Carica papaya Seed Extract Composition Using GC/MS Analysis

Some of the common practices to assess the composition of plant extract,including Carica papaya seed extract(CPSE)are direct injection of the extract,compound separation using polyethylene glycol capillary column(DB-WAX),and non-linear-temperature programming(NLTP)of GC/MS analysis.This study specifically compared the coating of capillary column,sample derivatization,and temperature programming of GC/MS to determine the composition of CPSE.The retention indices(RI)of the detected compounds were determined and compared to the reference RI.In particular,5%phenyl-95%methylpolysiloxane(HP-5MS)-,DB-WAX-,and biscyanopropyl polysiloxane(HP-88)-coated capillary columns were used to identify the composition of CPSE.For this study,HP-5MS column,which separated the highest number of compounds(26 compounds)from CPSE,was deemed as the most suitable column.The GC/MS analysis of derivatized CPSE identified 21 compound groups,where fatty acids and fatty acid methyl esters served as the major compounds(80.23%),followed by these compounds in decreasing order:amides>nitriles>sterols>fatty aldehydes>organic acids.A stronger correlation determination between the carbon number and alkane retention time of linear-temperature programming(LTP)(R^(2)=0.9859)was found,as compared to its correlation determination with NLTP(R^(2)=0.9175),which exhibited an almost equal RI of LTP to the reference RI.Conclusively,GC/MS analysis for the derivatized CPSE using HP-5MS column separation and LTP is highly recommended.

Investigation on chiral capillary columns and their application in separation of enantiomers

Six chiral diamide stationary phases (CSPs), namely N-(3-carbobenzoxypropionyl)-L- Val-tert-butylamide (CSP-1), N-undecenoyl-L-Val-S-α-phenylethylamide (CSP-2), N-undecenoyl-L- Val-R-α-phenylethylamide (CSP-3), OV-225-L-Val-tert-butylamide (CSP-4), XE-60-L-Val-tert- butylamide (CSP-5) and polycyanoethyl vinyl siloxane-L-Val-tert-butylamide (CSP-6), were inves- tigated and CSP-6 was crosslinked within narrow bore (70 μm) fused silica capillary columns. The separation of amino acid enantiomers on this narrow bore column by gas chromatography (GC) is illustrated.