Enzyme immunoassay of cyclazocine using peroxidase as label

A sensitive enzyme immunoassay for the determination of serum or urinary cyclazocine was developed. Horseradish peroxidase was used as the labelling enzyme; it was conjugated with cyclazocine derivatives by the mixed anhydride method. After the immune reaction, bound and free fractions were separated by a double-antibody solid-phase method, using Sepharose 4B gel coupled with purified IgG from goat anti-rabbit IgG serum. The enzyme activity was measured fluorophotometrically, with p-hydroxyphenyl propionic acid and hydrogen peroxide as substrates. The correlation coefficients verified that there was excellent agreement between the results obtained by the new enzyme immunoassay and those of radioimmunoassay (r=0.92) and gas chromatography-mas spectrometry (r=0.94).