Multi-elemental analysis of sulfuric acid by oaTOF-ICP-MS after matrix modification with barium bromide

Abstract

In this work a novel method for the simultaneous multi-elemental analysis of sulfuric acid by inductively coupled plasma orthogonal acceleration time-of-flight mass spectrometry (oaTOF-ICP-MS) after matrix modification with barium bromide was introduced. For this purpose sample aliquots consisting of 10% (w/w) sulfuric acid were mixed with barium bromide and after the precipitation of sulfates, the resulting liquid phase was aspirated with a concentric glass nebulizer for TOF-ICP-MS determination. The separation of sulfur as a precipitated non-soluble barium sulfate enables the elimination of spectral interferences originating from different sulfur containing species like SN+, SNH+, SO+, SOH+, SOH2+, SCO+, SNOH+, SO2+, S2+, SO2H+, or S2H+ on the determination of e.g. Ti, Zn, Ge, and Cu. After that, direct, reliable, and simultaneous determination of 15 elements (Be, Ti, V, Cr, Mn, Ni, Co, Cu, Zn, Ga, Ge, As, Sn, Sb, and Te) at trace and ultra-trace levels in sulfuric acid were performed under optimum instrumental conditions and by using Rh as an internal standard. Accuracy and precision were assessed by analysing sulfuric acid and by comparison of the results of the proposed method with those obtained by the high resolution ICP-MS method. The results of both methods were in good agreement for Ti, V, Cr, Mn, Ni, Co, Cu, Zn, Ga, Ge, and As. The accuracy for all of the 15 elements was also checked by an analytical recovery study. The reported method has a precision greater than 12.5%.