Determination of antimony in gunshot residues (GSR) by electrothermal atomic absorption spectrometry

Abstract

Simple and fast analytical procedure for antimony determination in gunshot residues by electrothermal atomic absorption spectrometry (ETAAS) is described. The sampling method of swab was tested by using adhesive tapes and both cotton rod and bandaged cotton moistened with boric acid. The optimal instrumental parameters for ETAAS measurements are defined: the maximum loss free pretreatment temperature found was 700 degrees C and the optimum atomization temperature was 1800 degrees C. Experiments performed with various modifiers (Pd, Ni, ascorbic acid, boric acid) showed that 5% (m/v) of boric acid is the most suitable modifier for Sb ensuring interference free ETAAS measurements. Linear analytical curve is ranging from 5 mu g.L-1 to 40 mu g.L-1 (R-2 = 0.9998, n = 3). Limit of detection (LOD) and limit of quantification (LOQ) calculated under optimum conditions are 0.4 mu g.L-1 and 1.3 mu g.L-1, respectively. The degree of interferences from matrix elements like Na, K, Ca, Fe, Pb, Ba, Ag, Cl, SO4 and PO4 was investigated and evaluated. Recoveries in the range 70-88% were achieved.