Enantioselective high-performance liquid chromatographic method for the determination of baclofen in human plasma

Abstract

A new analytical method for the separation and determination of R-(−)- and S-(+)- baclofen enantiomers in human plasma by high-performance liquid chromatography (HPLC) with UV detection was developed. Enantioselective resolution of the baclofen enantiomers was achieved by using teicoplanin macrocyclic antibiotic chiral stationary phase (CSP) known as Chirobiotic T with a polar ionic mobile phase (PIM) consisting of methanol: glacial acetic acid: triethylamine, 100:0.1:0.1, (v/v/v) at a flow rate of 0.5 ml min −1 and UV detection set at 220 nm. The analytes of interest with S-(+)-sulpiride as the internal standard were extracted from human plasma using liquid–liquid extraction procedure with ethyl ether under alkaline condition prior to HPLC analysis. Recoveries for R-(−)- and S-(+)-baclofen enantiomers were in the ranges of 96–103% at 60–2500 ng ml −1 level. Intra-day and inter-day precision calculated as %RSD was in the ranges of 1.2–5.2 and 1.3–4.3% for both enantiomers, respectively. Intra-day and inter-day accuracy calculated as percentage error were in the ranges of 1.2–3.9 and 1.1–3.9% for both enantiomers, respectively. Linear calibration curves in the concentration ranges of 20–3000 ng ml −1 for each enantiomer showed correlation coefficient ( r) of 0.9997. The limit of quantitation (LOQ) and limit of detection (LOD) for each enantiomer in human plasma were 20 and 10 ng ml −1 (S/N=3) respectively.