ION-PAIR REVERSED-PHASE LIQUID-CHROMATOGRAPHY OF ARSENIC SPECIES ON POLYMERIC STYRENE-DIVINYLBENZENE PACKED-COLUMNS WITH AN ALKALINE AQUEOUS MOBILE PHASE

The resolving power of an ion-pair reversed-phase liquid chromatography method, on a polymeric stationary phase (PRP-1) with an alkaline aqueous mobile phase (pH = 9) containing tetrabutylammonium cation as ion-pairing agent, is compared with a traditional ion-pairing system using an octadecyl-modified silica column and a neutral aqueous mobile phase (pH = 7.3). This chromatographic system (PRP-1 column) provides a rapid means for the determination of two of the most important arsenic species, arsenobetaine and arsenite. Addition of methanol (5 %) to the aqueous mobile phase allows the differentation of arsenobetaine from the system peak when using UV detection.