Analytlca Chrmrca Acta, 269 (1992) 109-114 Elsevler Science Pubhshers B V , Amsterdam 109 Flow injection and liquid chromatographic postcolumn detection of amino acids by mimetic peroxidase-catalysed chemiluminescence reaction Yun-Xlang Cl, Jlan-Ke Tie, Qm-We1 Wang and Wen-Bao Chang Department of ChemrSrry Belpng Umversrty, Ber/mg 100871 (Chum) (Received 3rd March 1992, revised manuscnpt received 12th May 1992) zyxwvutsrqponmlkjihgfedcbaZ AbStIWt Four ammo acids were determmed on the basis of the findmg that the catalytic activity of mimetic peroxldase. (metalloporphynn) m the chemdummescence reaction between lummol and hydrogen peroxide IS mhltuted m the presence of an ammo acid The degree of chenuhunmescence mhlbltlon IS a measure of the ammo acid concentra- tion The electrostatic mteractlon between ammo acid and metalloporphynn was confirmed by comparmg the degree of mhlbltlon of cationic and anionic metalloporphyrm-catalysed chemdummescence reactions More than 20 ammo acids were tested, and only L-cysteme, L-tyrosme, L-tryptophan and L-cystme slgmficantly quenched the chenuluml- nescence mtenslty Detection limits were 6 8 X 10-s, 13 X lo-‘, 8 5 X 10e6 and 2 2 x lo-’ M, respectively The detection approach IS demonstrated with a sdca-based hqmd chromatographlc separation of ammo acids usmg phosphate buffer (pH 7 3) as mobde phase Compared with other chemdummescence analyses, this method LS faster, can be run at room temperature and, m favourable cases, has a lower detection hnut Keywords Chemdummescence, Flow inJection, Liquid chromatography, Ammo acids, Metalloporphynns It 1s well established that ammo acids can be determined by measuring the amount of hydro- gen peroxide formed during the reaction of the ammo acrd with its oxldase The hydrogen perox- Ide that 1s formed 1s typically determined via the use of a chemdummescence (CL) reaction Of the different CL reagents available, peroxyoxalate or lummol appear to be the most popular [ll Sev- eral oxalates have been investigated for their stability m the presence of hydrogen peroxide and CL intensity Unfortunately, none of them combines all the required characterlstlcs and of- ten compromises have to be made In the lummol CL system, the high pH required for efficient Correspondence to Yun-Xlang Cl, Department of Chemistry, Belpng University, Beijing 100871 (China) light productions 1s not compatible with most enzymatic reactions Consequently, the most srg- mflcant problem wrth such enzyme-coupled CL detection reaction schemes IS that a two-stage reaction sequence must be employed [2,31 Nle- man and co-workers [4,5] developed a hquld chromatographlc (LC) detection method for ammo acids based on the suppression of CL m the co(II)- and Cu(II)-lummol-peroxIde sys- tems Our interest has been m the use of metallopor- phyrms (M-Pr) as a substitute for peromdase m analytical applications Vanous M-Pr have been used as mimetic peroxldase m fluorescence and CL analysis [6-81 Recently, it was found that the catalytic activity of M-Pr m the CL reaction of lummol and hydrogen peroxide 1s inhibited m the presence of an ammo acid and approaches a 0003-2670/92/$05 00 0 1992 - Elsevler Science Publishers B V All rights reserved