Determination of phencyclidine by radioimmunoassay

A radioimmunoassay (RIA) was developed for measurement of phencyclidine (PCP) and its monohydroxy metabolites in urine. Anti-PCP serum was generated in rabbits and the labeled antigen was prepared by radio-iodination (125I) by the Hunter-Greenwood procedure. Adjustment of the antiserum and 125I-antigen concentrations resulted in a dynamic response from 0 to 200 ng/ml and as little as 2 ng/ml was detected. Reagents were stable for at least three months at 2 to 8 degrees C. Most (95%) urine specimens from presumed nonusers contained less than 5 ng/ml and urine specimens from suspected abusers usually exceeded 100 ng/ml. Comparison of RIA with other methods for detection of PCP showed good agreement. Cross-reactivity with other commonly prescribed drugs was not encountered. The recovery of PCP was 93 to 109% over the 20 to 175 ng/ml concentration range and the reproducibility (average coefficient of variation) was +/- 13%. Development of the RIA for PCP has resulted in a rapid procedure that can be adapted to automated processing and is also suitable for small-scale testing.