Simultaneous Determination of As and Hg in Fertilizers by Hydride Generation-Atomic Fluorescence Spectrometry with Microwave Digestion

A method for the determination of As and Hg in fertilizer by hydride generation-two-way-atomic fluorescence spectrometry has been established using the pretreatment by microwave digestion technique. 20 g/L KBH₄ for reductant and 8% HCl for carrier fluid. Optimal instrument conditions were HV of -270 V for As and Hg measurements with As lamp current of 60 mA and Hg lamp current of 20 mA. Interference from common elements in the determination of As and Hg are discussed in this paper. The effect of the main elements of N, P and K (40 g/L) and impurity elements of Te, Ca, Zn, Cu, Cr, Mn, Ni, Sb, Sn and Pb, which was ten times those of As, Hg, met the requirements of analytical chemistry. The method for determination of As and Hg had a wide linear range of 0.68-100 μg/L and 0.12-10 μg/L, respectively. The detection limits for As and Hg were 0.68 μg/L and 0.12 μg/L, respectively. The method was applied to determine real sample and the RSD (n=5) for As in phosphate fertilizer was 4.22% and 7.53% in potash fertilizer, the RSD (n=5) for Hg in phosphate fertilizer was 5.89% and 4.41% in potash fertilizer. This method is rapid and simple with a high accuracy and sensitivity, and can be applied to measure As and Hg in nitrogen fertilizer, phosphate fertilizer and potash fertilizer, providing a reference for correlated detection departments to monitor the quality of the fertilizer.