OPTIMIZATION OF THE AMPEROMETRIC DETECTION OF NITRITE BY REACTION WITH IODIDE IN A POSTCOLUMN REACTOR FOR LIQUID-CHROMATOGRAPHY OF NONVOLATILE NITROSAMINES

Following previous studies on this subject, the use of iodide reagent in acidic medium for the liquid chromatographic amperometric determina tion of non-volatile nitrosamines has been investigated in a two-line flow-injection manifold coupled with a voltammetric flow-through detec tor. The peak current signals obtained for the nitrite-iodide reaction were compared with those obtained for the iodate-iodide reaction used as a reference for the production of the electroactive species I-3(-) The effect of adsorption-desorption phenomena on the reactor walls wa s investigated and analyzed by the ''exponentially modified Gaussian'' model applied to flow-injection peaks obtained under different experi mental conditions, as to composition of the carrier liquid (water and water-acetonitrile mixtures), concentration of the reagent and tempera ture of the reactor. From an analytical point of view, the method ensu res a satisfactory linear response, a higher sensitivity and a much lo wer detection limit (about 1x10(-8) M) than those found with the ceriu m(IV) reagent, and a comparable band broadening and tailing.