Effects of urine acidification on plasma and urine phencyclidine levels in overdosage.

A gas chromatography--mass fragmentography--electron impact (GC-MS-EI) assay of phencyclidine (PCP) was adapted for human plasma and urine. This assay is specific for PCP and very sensitive (approximately 1 ng/ml). Patients with the putative diagnosis of PCP overdosage were studied to correlate plasma and urinary levels with clinical state. Urinary PCP levels were enhanced in an acid urine, which suggests that acidification of the urine is an adjunct in the therapy of PCP overdosage.