DETERMINATION OF 10 ORGANOARSENIC COMPOUNDS USING MICROBORE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY COUPLED WITH ELECTROSPRAY MASS-SPECTROMETRY MASS-SPECTROMETRY

An analytical method based on reversed-phase microbore HPLC coupled on -line with electrospray mass spectrometry (ES-MS) is described, The me thod allows for the determination of up to ten organoarsenicals in a s ingle chromatographic run. Excellent sensitivity and selectivity is ac hieved by operating the triple quadrupole mass spectrometer in the sel ected-reaction monitoring mode, This is possible because the ions prod uced by collision-induced dissociation of the protonated molecules or molecular ions of the ten organoarsenicals are characteristic of each compound, The best LODs, achieved in the positive-ion mode, were betwe en 2 and 21 pg of arsenic and corresponded to arsenicals which exist a s cations in acidic solutions, The selectivity achieved by using this method allows for successful determination of arsenicals co-eluting du ring HPLC, This is a major improvement over other hyphenated technique s already used for arsenic speciation, e.g., HPLC-ICP-MS. Furthermore, the method was used for the analysis of an undiluted urine SRM in whi ch arsenobetaine was determined to be present at the low mu g l(-1) le vel.