Determination of Mercury in Iron Supplement Using Slurry Sampling and Cold Vapor Atomic Absorption Spectrometry

This paper proposes a method using slurry sampling and cold vapor atomic absorption spectrometry (CV AAS) for the determination of mercury in iron supplement used for the treatment of anemia. The optimization step of the slurry preparation was performed using a two-level full factorial design involving the experimental factors: hydrochloric acid concentration, thiourea concentration and sonication time, having as chemometric response the absorbance. Employing the optimized conditions, the method allows the determination of mercury, using external calibration technique, with limits of detection and quantification of 30 and 102 ng L-1, respectively. The precision expressed as a relative standard deviation (RSD) was 10.89 and 6.84% for supplement samples with mercury content of 4.82 and 9.61 ng g-1, respectively. The limits of detection and quantification, considering a sample mass of 1.2 g, were 0.63 a 2.10 ng g-1, respectively. There is no certified reference material of ferrous supplement for evaluation of the accuracy. Thus, addition/recovery tests were performed to evaluate the accuracy of the method. The recovery values achieved varied from 85 to 106%, confirming the applicability of this method for mercury quantification in these iron matrices. The method was satisfactorily applied for the determination of mercury in twelve iron supplement samples with different chemical compositions. In six samples, the mercury content was lower than the limit of quantification (2.10 ng g-1) and in the other six samples, the mercury content varied from 3.17 to 34.86 ng g-1.