CAPILLARY ELECTROPHORESIS STEREOSELECTIVE DETERMINATION OF R-(-PENTOBARBITAL AND S-(-)-PENTOBARBITAL FROM SERUM USING HYDROXYPROPYL-GAMMA-CYCLODEXTRIN, SOLID-PHASE EXTRACTION AND ULTRAVIOLET DETECTION())

Pentobarbital is a sedative hypnotic which is used in the treatment of people suffering from anxiety related conditions and to manage elevat ed intracranial pressures and cerebral ischemia due to neurosurgical p rocedures. This paper develops and validates a rapid and sensitive met hod for the determination of S-(-)- and R-(+)-enantiomers in serum usi ng capillary electrophoresis (CE) and UV detection. Stereoselective re solution was accomplished using 40 mM hydroxypropyl-gamma-cyclodextrin contained in 50 mM phosphate buffer pH 9.0; The method involves a sol id-phase extraction of both the enantiomers and the internal standard, aprobarbital, from serum using C-18 Bond-Elut cartridges. The CE syst em consists of a 52 cmx75 mu m I.D. fused-silica capillary maintained at a run voltage of 15 kV with sample detection performed at 254 nm. T he detection and quantitation limits for S-(-)- and R-(+)-pentobarbita l are 1 mu g/ml from serum. Linear calibration curves from 1 to 60 mu g of both S-(-)- and R-(+)-enantiomers show a coefficient of determina tion of more than 0.999. The precision and accuracy of the method calc ulated as R.S.D. and error are 0.20-2.20% and 0.00-4.40%, respectively for R-(+)-pentobarbital and 0.30-2.19% and 0.30-6.40%, respectively f or S-(-)-pentobarbital. (C) 1997 Elsevier Science B.V.