Direct determination of arsenic in beer by electrothermal atomic absorption spectrometry with deuterium background correction (D2-ET-AAS)

We describe here a method for the direct determination of As in beer by D2-ET-AAS, using Pd modifier, the atomization from platform and insertion of a cooling step before atomization. This method results in a 40% increase of sensitivity in peak-height measurements. Pd was found to be the most advantageous chemical modifier for the elimination of phosphate interference compared to Ni or Pt + citric acid. In addition, Pd is able to stabilize As at charring temperatures of 1500 °C and further addition of V, Mg or Sr have no influence. Addition of the modifier to standards and samples made possible the use of matrix-free standard solutions for attaining accurate analysis of diluted samples. The accuracy was checked by the comparison of results of direct analysis of beer samples by the proposed method with those found for microwave-digested samples measured by an inductively coupled plasma orthogonal acceleration time-of-flight mass spectrometer (ICP-oa-TOFMS) method. The accuracy was also confirmed by the analysis of certified reference samples.