Simultaneous determination of As, Hg, Sb, and Se in mineral fertilizers using ultrasonic extraction and CVG-ICP OES

A method for the simultaneous determination of As, Hg, Sb and Se in fertilizers by axial view inductively coupled plasma optical emission spectrometry using on-line chemical vapor generation is proposed. The sample added with aqua regia is sonicated for 15 minutes. The concentrations of NaBH4 and HCl used for the chemical vapor generation and plasma power were evaluated using a fertilizer sample from an interlaboratory program, which was digested in a microwave oven or sonicated in the presence of aqua regia. For a 100 mg sample, the obtained detection limits (LODs), were 0.5 mg g(-1) (As), 0.1 mg g(-1) (Hg), 1.0 mg g(-1) (Sb) and 0.6 mg g(-1) (Se). The obtained results for the standard reference material NIST 695 were in agreement with the certified values, according to the t test, for a confidence level of 95%, with the following relative standard deviation ranges: 2-5% (As), 4-9% (Hg) and 5-10% (Se). For Sb the results were adequate in comparison with that obtained by ICP-MS (inductively coupled plasma mass spectrometry), used as an independent technique. The procedure is simple and fit-for-purpose with sufficient detection power to screen for simultaneous determination of As, Hg, Sb and Se at trace levels in mineral fertilizers.