Evaluation of a new phencyclidine enzyme immunoassay for the detection of phencyclidine in urine with confirmation by high-performance liquid chromatography-tandem mass spectrometry.
We present an evaluation of a new phencyclidine (PCP) enzyme immunoassay (PCPI) for detection in urine. The PCPI was evaluated by testing 523 urine specimens. Controls containing 0 ngmL of PCP and -25% (negative control) and 25% (positive control) of the 25 ngmL cutoff calibrator were analyzed with each batch. All urines were analyzed by high-performance liquid chromatography- tandem mass spectrometry (HPLC-MS-MS) for PCP. Of the 523 specimens tested, 218 yielded positive results by the PCP assay. HPLC-MS-MS confirmed the presence of at least 25 ngmL in 214 specimens, indicating four false-positive results containing 11, 13, 16, and 20 ngmL PCP. Three specimens yielded a negative result however, PCP concentrations were within 20% of the 25 ngmL cutoff value. The overall agreement of PCPI and HPLC-MS-MS results was 98.7%. The sensitivity of the PCPI was 0.982 and the specificity 0.987. Testing at 100 ngmL of other drugs or their metabolites demonstrated no cross-reactivity. The within-run precision was CV 2% (n 12) the between-run precision was CV < 6% (n 4). The assay was found linear from -50% to 150% (12.5-37.5 ngmL) of the cutoff concentration. The Lin-Zhi PCPI provides a precise, reliable method for the routine detection of phencyclidine in urine specimens.