Combination of suppressed and non-suppressed ion chromatography with atmospheric pressure ionization mass spectrometry for the determination of anions

Non-suppressed and suppressed ion chromatography in combination with atmosp heric pressure ionization mass spectrometry are compared with special respe ct to sensitivity for the analysis of low-molecular-mass anions. Iodate, br omate, bromide, sulfate, thiosulfate and bromide could be separated by non- suppressed ion chromatography using a low-capacity anion-exchange column an d ammonium citrate as mobile phase. Absolute detection limits between 0.4 a nd 0.7 ng could be achieved; employing a column requiring a flow-rate of 1 ml/min for optimum performance, splitting was necessary so that only 120 mu l/min entered the interface of the mass spectrometer resulting in detectio n Limits between 0.03 and 0.06 mg/l. The same stationary phase (packed into a narrow-bore column which allowed operation without: splitting) was suita ble for the separation of oxyhalides in the suppressed mode with detection limits of 0.5 mu g/l (50 pg) with sodium carbonate as eluent. The method wa s applied to the analysis of drinking water for oxyhalides. The sample pret reatment for the removal of matrix anions (sulfate, chloride and hydrogenca rbonate) is described. (C) 1999 Elsevier Science B.V. All rights reserved.