Determination of the (+)- and (-)-enantiomers of Pirprofen in Human Plasma by High-performance Liquid Chromatography

A high-performance liquid chromatographic (HPLC) method was developed to determine the (+)- and (-)-enantiomers of pirprofen, an anti-inflammatory drug. After addition of an internal standard, the plasma sample was brought onto a glass column pre-packed with silica and eluted with dichloromethane. The extracts were derivatized with 1,1'-carbonyldiimidazole and R (+)-1-methylbenzylamine to form the two diastereomeric amides. The diastereoisomers were separated on a chiral column by HPLC with ultraviolet detection at 272 nm using n-hexane-dichloromethane (64:36, v/v) as the mobile phase. The limit of quantitation was 0.992 mumol/l (0.25 microgram/ml) for each enantiomer.