STEREOSELECTIVE SEPARATION AND DETECTION OF PHENOXY ACID HERBICIDE ENANTIOMERS BY CYCLODEXTRIN-MODIFIED CAPILLARY-ZONE-ELECTROPHORESIS ELECTROSPRAY-IONIZATION MASS-SPECTROMETRY

An application of on-line coupling of capillary electrophoresis and ma ss spectrometry (CE-MS) to the chiral separation of phenoxy acid herbi cide enantiomers was investigated. As an ionization method, electrospr ay ionization (ESI) is used for a CE-MS interface. Generally, nonvolat ile additives in separation solutions sometimes decrease the MS sensit ivity and/or signal intensity. In this study, however, heptakis(2,3,6- tri-O-methyl)-beta-cyclodextrin (TM-beta-CD) was used as a chiral sele ctor and it migrated directly into the ESI interface. By using the neg ative-ionization mode along with a methanol-water-formic acid solution as a sheath liquid and nitrogen as a sheath gas, stereoselective sepa ration and detection of three phenoxy acid herbicide enantiomers were successfully achieved with a 20 mM TM-beta-CD in a 50 mM ammonium acet ate buffer (pH 4.6). (C) 1998 Elsevier Science B.V. All rights reserve d.