Development of a closed infrared-assisted system for sample digestion in trace element analysis procedures

Abstract

Trace element analysis in organic samples commonly requires a sample digestion step for releasing the elements of interest from the solid matrix into solution and reduce organic carbon content that might be an interferent for many analytical techniques. In this work, a high pressure and temperature wet digestion system assisted by infrared radiation (IR) was developed. The IR-assisted closed system was assembled using halogen lamp (500 W), a power control of the lamp, quartz vessels with lock, relief valve and temperature control. The experimental parameters of digestion procedure were studied using a full factorial design. The optimal condition was 15 min of heating time to 200 °C, remaining at 200 °C during 5 min. The total organic carbon (TOC) content of two reference materials (fish tissue and bovine liver) after digestion was quantified to evaluate the efficiency of the proposed system. The TOC content in the digests (60 mg L⁻¹) was compatible with ICP-OES, which makes feasible the quantification of Ca, Cu, Fe, K, Mg and Zn in the samples with accuracy. The IR-assisted closed system proved to be a promising, operational and cost-effective arrangement to be applied as an alternative for organic sample digestion to aim elemental trace analysis.