Mercury determination in various environmental, food and material complex matrices using unified operating conditions for a cold vapor generation high-resolution continuum source quartz tube atomic absorption spectrometry method

Abstract

An analytical method with broad applicability based on cold vapor generation high-resolution continuum source quartz tube atomic absorption spectrometry was developed and evaluated for the determination of total mercury in matrices with various complexities and compositions. Sample preparation for different matrices of food, environmental samples and (bio)polymeric materials and unified operating conditions for derivatization and measurement were evaluated. The method was validated according to established requirements (Eurachem Guide 2014, EC Decisions 657/2002; 333/2007; 836/2011 and Association of Official Analytical Chemists Guide – AOAC). Analytical versatility was checked on various samples of fish fillets, mushrooms, soil, water and water sediment, sludge from a wastewater treatment unit, and (bio)polymeric materials from waste recycled from food packaging, computers and garden tools. Under optimal conditions for cold vapor generation in a batch system, namely 3% (v/v) HCl as reaction medium for 5 mL aliquot samples and a volume of 3.5 mL 0.3% (m/v) NaBH₄ stabilized in 0.2% (m/v) NaOH as derivatization reagent, the detection limit for Hg in terms of peak height measurement (n = 7 days) was in the range 0.064 ± 0.004 μg L⁻¹ in water, 0.014 ± 0.001 mg kg⁻¹ in environmental samples and 0.009 ± 0.001 mg kg⁻¹ in (bio)polymeric materials. Overall recovery of Hg by analysis of certified reference materials was 102 ± 20% (k = 2) in food, soil, wastewater and water sediment, and polyethylene. Precision for the measurement of various real samples ranged between 4.2 and 15.0%. A performance study highlighted that the method was sensitive, free of non-spectral interference coming from the multielemental matrix and that it complied with the requirements for Hg determination set in EC Decisions and AOAC Guidelines at least for the more common matrices analyzed for social impact.