The determination of meperidine, noremeperidine and deuterated analogs in blood and plasma by gas chromatography mass spectrometry selected ion monitoring.

A gas chromatographic mass spectrometric assay using selected ion monitoring for meperidine and normeperidine in blood and plasma is described. Both unlabeled and [3H]-phenyl ring labeled drugs may be determined simultaneously using [2H10] analogs as internal standards. Calibration curves are linear over the range 5--100 ng ml-1, the results reproducible (coefficient of variation < 5%), the sensitivity limit is about 5 ng using a 1 ml sample and no interference is present in blank blood or plasma, or by isotope inpurity. The method is shown to be applicable to measuring the concentration of meperidine and its metabolite, normeperidine, in blood, following simultaneous administration by the intravenous and oral routes of 25 mg each of unlabeled and [2H5] labeled drug, respectively.