DETERMINATION OF N-NITROSOPIPERIDINE IN BEERS BY LIQUID-CHROMATOGRAPHY WITH REDUCTIVE AMPEROMETRIC DETECTION AT A HANGING MERCURY DROP ELECTRODE

Liquid chromatographic separation prior to reductive electrochemical determination at the hanging mercury drop electrode is used to determine N-nitrosopiperidine (NPIP). A mobile phase of methanol-acetonitrile-phosphate buffer, pH 3.5 (57:38:5) is used with the detector operated in the direct current (DC) mode at E(p) = -1250 mV. Techniques for oxygen removal and electrochemical considerations are presented. The detection limit is 0.2 ng injected with a relative standard deviation (n = 10) of 2.8%. The method can be applied to the determination of NPIP in beers. Conditions for the prior extraction of NPIP from beer samples have been established using solid phase extraction cartridges.