The mfluence of metal IOILS on the peroxyoxalate chenuhunmescence reaction was mvestlgated usmg batch experunents A number of metal ions showed an unprovement of the chenulummescence reactlon of b&2-mtrophenyl) oxalate Hnth hydrogen percande m the presence of 3-ammofluoranthene as the fluorophore and mndazole as the catalyst Copper gave the highest enhancement, of about one order of magmtude The reason for the Increase m the chemdummescence mtenslty by metal lolls IS probably a change m the mechamsm of the peroxyoxalate chemdummescence readon due to stabtiatton of the oxalate ester-mudazole complex by the metal Ion, leadmg to a higher efficiency of the chenuhmunescence reaction Keywords Chemdummescence, Copper; Metal eons, Peroxyoxalate chenulummescence Chermlurmnescence (CL) IS the enusslon of hght after excitation of a fluorophore by a chemlcal reactlon, and numerous CL reactrons are now known The most frequently used systems are based on lummol, luclgemn or peroxyoxalate chermstry However, for on-hne detection m column hquld chromatography (LC), the peroxyoxalate system has been used almost excluswely Peroxyoxalate CL takes place when an oxalate ester reacts mt.h hydrogen peroxide m the pres-Cownce to 0 M Steuger, Department of Analytxal Chenusm, Free Umverslty, De Boelelaan 1083, 1081 HV Amsterdam (Netherlands) ence of a suitable fluorophore and a base catalyst Suitable fluorophores are those vvlth an excltatlon energy of up to about 400 kJ mol -l [ 1,2] and a low oxldatlon potentml [2,3] The observed CL corresponds to the enusslon of the first excited state of the fluorophore This means that the role of the oxalate ester and hydrogen perox-Ide 1s to generate this excited state However, the formatton of the mtermedlate(s) has not yet been fully clartied Although m 1963 Chandross [4] started research to elucidate the mechamsm of the peroxyoxalate CL reaction m non-aqueous solvents, only recently was a kmetic model described by Glvens