Separation of enantiomers by capillary electrophoresis-mass spectrometry employing a partial filling technique with a chiral crown ether

Enantiomer separations were performed by capillary electrophoresis-mass spe ctrometry (CE-MS) with (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid (18C 6H(4),) as a chiral selector. In order to prevent the introduction of the n onvolatile chiral selector, 18C6H(4), into the nozzle of the CE-MS interfac e and/or the orifice plate, a partial filling technique was employed in thi s study. By the partial filling technique, the contamination caused by the nonvolatile chiral selector was avoided not only during the analysis but al so during the washing of capillary with the separation solution prior to th e run. Several racemic compounds having a primary amino group were successf ully separated. Racemic 3-aminopyrrolidine and racemic alpha-amino-epsilon- caprolactam have no strong UV absorption, but such compounds were detected with a high sensitivity by MS detection. In this paper, the effects of the length of separation zone and those of the 18C6H(4), concentration were des cribed. As the length of the separation zone was longer or as the concentra tion of 18C6H(4), was higher, the enantiomer resolution was enhanced more a nd more. However, the optimization of 18C6H(4), concentration was practical ly enough to obtain the baseline separation. (C) 2000 Elsevier Science B.V. All rights reserved.