COMPETITIVE ENZYME-IMMUNOASSAY FOR URINARY VANILLYLMANDELIC ACID

An enzyme immunoassay for urinary vanillylmandelic acid (VMA) using po lyclonal antiserum and VMA-acetylcholinesterase conjugate as enzymatic tracer is described. Two different strategies for immunogen preparati on were developed and enantioselectivity was demonstrated. Selected EI A allowed direct measurement of urinary VMA using D(-)-VMA as standard with good sensitivity (MDC = 0.1 mu mol/l) and precision (CV less tha n 7% in 0.2-2.25 mu mol/l range). Cross-reactivity with homovanillic a cid (HVA) was 0.8% and less than 0.4% with other structurally related catecholamine metabolites. Intra- and inter-assay repeatability were l ess than 10% and recovery was 97.3%+/-3%, Good correlation was obtaine d for EIA and HPLC analysis with normal and pathologic human urine sam ples (EIA = 0.895 HPLC-7.085, r(2) = 0.98, n = 47). (C) 1997 Elsevier Science B.V.