Gas-chromatographic analysis for phencyclidine in plasma, with use of a nitrogen detector.

We describe a reliable gas-chromatographic analysis for unchanged phencyclidine in human plasma, with use of a nitrogen detector. The assay is sufficiently sensitive to permit measurement of as little as 5 microgram of the drug per liter, in 2 mL of plasma. Phencyclidine is extracted from plasma at pH 10.5 into hexane/iso-amyl alcohol containing meperidine as the internal standard, back-extracted into dilute HCl, and re-extracted into hexane/iso-amyl alcohol after alkalinization of the HCl. The coefficients of variation for the analysis at respective concentrations of 100 and 200 microgram/L are: within-run 4.0% and 3.4%; between-run, 2.8% and 5.2%. This procedure, used in our laboratory for more than one year, has been applied to plasma from numerous individuals with nonfatal phencyclidine intoxication. Some representative examples are given.