The　diazo　coupling　reaction　of　diazotized　p-aminoacetophenone　(DPAAP)　with　histidine　and　its　metabolites　form　the　basis　of　the　differential　pulse　adsorption　stripping　voltammetry　(DPASV)　method　for　determination　of　histidine　and　its　metabolites.　The　adsorption　and　electrochemical　reaction　mechanism　of　the　coupling　products　were　studied　in　detail　by　structure　analysis,　cyclic　voltammetry,　chronocoulometry,　control　potential　electrolysis,　electrocapillary　curves,　UV　spectroscopy　and　the　effect　of　temperature　and　surfactants.　The　adsorption　of　azo-histidine　was　found　to　obey　Frumkin　adsorption　isotherm.　The　calculation　results　of　the　maximum　surface　excess　(Gamma(m)　=　3.08　x　10(-11)　mol　cm(2)),　diffusion　coefficient　(D　=　2.27　x　10(-6)　cm(2)　s(-1)),　adsorption　coefficient　(beta　=　1.06　x　10(7))　and　interactive　factor　(gamma　=　0.9900)　showed　that　the　azo-histidine　conjugation　molecules　adsorbed　on　the　mercury　electrode　surface　were　attracted　each　other　and　the　electrode　process　was　adsorption　controlled.　(C)　1999　Elsevier　Science　B.V.　All　rights　reserved.