ELECTROANALYTICAL DETERMINATIONS OF HALAZEPAM - STUDY OF INTERACTION WITH HUMAN, SERUM-ALBUMIN

The electrochemical behavior of the benzodiazepine halazepam was inves tigated by differential pulse and tast polarography in water/methanol solutions. Reduction of halazepam was performed in one irreversible, d iffusion-controlled step using Britton-Robinson buffers. The peak pote ntial at pH 8.5 and a 10% methanol/water solution was -1.10 V (vs Ag/A gCl/3 M KCl). Halazepam can be determined at nanomolar levels, using a dsorptive stripping voltammetry. Applicability of tests on commercial preparations and human urine are described. The detection limit was 25 ng ml(-1) of urine for an accumulation time of 20 s; the mean standar d deviation was lower than 3.0% for 264 ng ml(-1) samples (n = 3) with a mean recovery of 97%. A study of the interaction of human serum alb umin with halazepam and diazepam has been performed by differential pu lse polarography; a lower affinity of halazepam for HSA was establishe d. (C) 1995 Academic Press, Inc.