COMPETITIVE ENZYME-IMMUNOASSAY WITH MONOCLONAL-ANTIBODY FOR HOMOVANILLIC-ACID MEASUREMENT IN HUMAN URINE SAMPLES

A fast competitive enzyme immunoassay (EIA) for measuring homovanillic acid in human urine samples was developed with a monoclonal antibody and acetylcholinesterase as enzyme label. Enzyme detection was perform ed by an easy colorimetric assay. Monoclonal antibodies were screened on the basis of sensitivity, specificity, and correlation studies. EIA has a detection limit of 0.5 mu mol/L, a CV <10% in the 1.25-10 mu mo l/L range, and intra- and interassay CVs of <10%. Crossreactivity with vanillylmandelic acid was 0.5% and <8% for other structurally related catecholamine metabolites. Parallelism of the EIA was shown in diluti on studies and the correlation with routine HPLC assay in 62 normal an d pathologic samples was EIA = 1.492 (HPLC) - 3.46, S-y\x = 47.52, ran ge = 4-1800 mu mol/L, r(2) = 0.977. Additional data concerning the val idity of this assay were provided by HPLC analysis of urinary immunore active material.