Analysis of meperidine and normeperidine in serum and urine by high-performance liquid chromatography.

A high-performance liquid chromatographic method is described for the simultaneous analysis of meperidine and normeperidine in serum and urine. A 1-ml sample aliquot is extracted into hexane, then back-extracted into a small volume of dilute acid which is injected onto a cyanopropyl analytical column. Absorbance of the column effluent is monitored at 205 nm. Two internal standards are employed, diphenhydramine for meperidine and nordiphenhydramine for normeperidine. Chromatography of the four compounds takes 4 min. Serum concentration--time curves of meperidine and normeperidine are presented for eight healthy subjects following single 70-mg bolus injections of meperidine.