HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY OF SELECTED ORGANIC PEROXIDES WITH OXIDATIVE AMPEROMETRIC DETECTION

Reversed-phase high-performance liquid chromatography with oxidative a mperometric detection was optimized for the determination of several o rganic peroxides in drinking mater under ideal conditions. The determi nations were performed under isocratic conditions using acetonitrile a nd methanol as the organic modifiers with 0.05 M potassium phosphate b uffer solution. The oxidative amperometric response of the organic per oxides was dependent on the concentration of organic modifier and the electrode potential. The optimum electrode potential (E-APP(Ox)), for the simultaneous determination of the organic peroxides was approximat ely +1.150 +/- 0.05 V versus the Ag/AgCl reference electrode, The maxi mum analytical signal for butan-2-one peroxide and tert-butyl hydroper oxide, when using acetonitrile, was obtained with 20% v/v organic modi fier. For cumene hydroperoxide, the maximum analytical signal was achi eved with approximately 35% v/v acetonitrile, The retention time of cu mene hydroperoxide, on an octyldecylsilane column (250 X 4 mm id), dec reased sharply from >100 to <10 min when the organic modifier concentr ation was varied from 5 to 50% v/v. The retention time of butan-2-one and tert-butyl hydroperoxide, under the same conditions, varied by <10 min. The calibration curves for the aliphatic peroxides and aromatic peroxide were linear from 2 to 200 ng and from 0.2 to 200 ng injected, respectively.