Nitrogen-phosphorous detection of phencyclidine in blood serum

A method for quantitating phencyclidine in the blood serum of rhesus monkeys with a solvent extraction procedure followed by gas chromatography with nitrogen-phosphorous detection is reported. Phencyclidine was extracted with ether from 0.5 ml of serum (pH 13.5) made basic with 2M NaOH, followed by back-extraction into 0.5 M sulfuric acid. After the addition of 2 M sodium hydroxide, phencyclidine was extracted into a small volume of ether for concentration and injection into the gas chromatograph. The limit of quantitation of phencyclidine in serum was 5 ng/ml. Recovery averaged 51.9 +/- 4.3%. Standard curves were linear between 5-50 ng/ml and 100-2000 ng/ml. Comparison between serum and aqueous standards indicated no interference by serum components in the extraction procedure. Pentobarbital, caffeine, and the monohydroxy metabolites of phencyclidine did not interfere with the analysis. This procedure is a rapid and sensitive method for determination of serum phencyclidine levels in animal studies requiring analysis of large numbers of samples.