Determination of the enantiomeric purity of S-ropivacaine by capillary electrophoresis with methyl-beta-cyclodextrin as chiral selector using conventional and complete filling techniques

Capillary electrophoresis (CE) methods based on the conventional and comple te filling techniques for determination of the enantiomeric purity of S-rop ivacaine are described. The complete filling technique is a separation meth od which can be used instead of the partial filling technique in order to r educe the total analysis time, when the chiral selector solution does not a bsorb UV light. Zn the complete filling technique the total length of the c apillary is filled with the chiral selector solution, prior to application of the analyte. During the run both ends of the capillary are connected to the background electrolyte, i.e. without chiral agent. An interlaboratory s tudy was performed to validate the method. The limit of detection and quant ification for R-ropivacaine were found to be about 0.6 and 1.6 mu g/ml, res pectively, corresponding to 0.1 and 0.25% enantiomeric purity of S-ropivaca ine. Good performances were demonstrated for the repeatability and linearit y. The consumption of the chiral selector was about 160 times lower with th e complete filling technique compared with the conventional CE technique. ( C) 1999 Elsevier Science B.V. All rights reserved.