Quantitation of Cocaine and Metabolites, Phencyclidine, Butalbital and Phenobarbital in Meconium by Liquid Chromatography-Tandem Mass Spectrometry.

In this study, a quantitative polarity switching liquid chromatography coupled with a tandem mass spectrometer (LC-MS/MS) method was developed to detect and quantify cocaine and metabolites (cocaethylene, benzoylecgonine and meta-hydroxybenzoylecgonine), phencyclidine (PCP) and barbiturates (phenobarbital and butalbital) in meconium. Accuracy and precision samples at 0.0125% and 75% of the upper limit of quantitation (ULOQ) were analyzed in triplicate over 5 days with accuracy above 84% and average %CV values below 11%. Within-run (n = 15) and between-run (n = 15) %CV values were ≤5%. Analytical measurement ranges were reproducible and linear (R ≥ 0.995) for cocaine and metabolites (20-2,000 ng/g), PCP (10-1,000 ng/g) and barbiturates (50-5,000 ng/g). Accuracy of 100 ± 20% was observed at (the limits of detection) 10 ng/g for cocaine and metabolites, 2.5 ng/g for PCP and 25 ng/g for barbiturates. No carryover was observed at 2X ULOQ and no interfering substances were identified. Sample preparation recoveries were 53-83%. Fifty-one authentic patient samples previously characterized correlated with the newly developed test having R2 values ≥0.996. This combined method allows accurate quantitation of the targeted drugs in a complex matrix while decreasing sample preparation and analysis time with reduced sample volume. Clinical data and positivity rates were similar to previously published positivity rates. Validation data and positivity rate agreement signifies a reliable and robust assay.