ELECTROSPRAY ION CHROMATOGRAPHY TANDEM MASS-SPECTROMETRY OF BROMATE AT SUB-PPB LEVELS IN WATER

An electrospray ion chromatography-tandem mass spectrometry (IC-MS/MS) method has been developed for the analysis of bromate ions in water. This IC-MS/MS method improves the limit of detection of bromate ions b y a factor of 10, The method consists of solid phase extraction with a n ion exchange column and elution of the analyte with water/methanol a mmonium sulfate eluent online with a negative ion electrospray mass sp ectrometry detection, SPE requires sample pretreatment to remove any m ajor ions that displace bromate, consisting of eliminating SO42-, Cl-, and HCO3- ions respectively with barium-form, silver-form, and acid ( H+ form) exchange resins. The methanolic sulfate eluent permits IC-MS coupling via an electrospray interface, BrO3- was selected in the firs t quadrupole (Q1) at two m/z values, 127 and 129, according to the iso tope contributions of Br-79 and Br-81, After fragmentation in the coll ision cell (second quadrupole, Q2), the third quadrupole (Q3) analyzes the product ions as (M - O)(-), (M - 2O)(-), and (M - 3O)(-), Among t he six recordable transitions, four were selected, the other two yield ing high background. A lowered resolution raised sensitivity by a fact or of up to 3. The limit of quantitation of this method was 0.1 mu g/L .