Evaluation of a Desolvating Microconcentric Nebulizer in Inductively Coupled Plasma Mass Spectrometry to Improve the Determination of Arsenic in Steels

Abstract

A desolvating microconcentric nebulizer (D-MCN) was used in inductively coupled plasma mass spectrometry (ICP-MS) in order to improve the determination of As in steels. To dissolve the samples, we applied a hydrochloric-nitric-hydrofluoric acid decomposition procedure. The isobaric interference of 40Ar35Cl+ due to the presence of Cl from the hydrochloric acid was minimized by using the desolvating device. Compared to results achieved with cross-flow nebulization, the As sensitivity was found to be 2.4 times higher, while the depression matrix effect caused by 0.1% m/v of Fe in the As signal was 3 times lower. The limit of quantification (LOQ) calculated as the concentration corresponding to 10 times the standard deviation of a procedural blank solution (0.1% m/v pure iron solution) was 0.12 μg g−1 (10 times better than that for the cross-flow nebulizer), and the background equivalent concentration (BEC) was about 25 times lower due to the absence of the most significant polyatomic interferences. The relative standard deviation calculated from six replicates at a concentration level of 10 times the detection limit was 0.8%. Three certified reference materials from the National Institute of Standard and Technology—NIST 365, 2165, and 2167—were analyzed; and recovery tests were performed on pure iron solutions spiked with different As contents. The close agreement of the values demonstrates the accuracy of the method.