Determination of Labile Mercury in Impressions of Total Solids Suspended in Natural Waters by Direct Analysis by Thermal Decomposition Comparing via Cold Steam Atomic Fluorescence Spectrometry [Determinação de Mercúrio Lábil em Amostras de Sólidos Totais SuspensosemÁguasNaturaisporAnáliseDiretaporDecomposição TérmicacomparandoviaEspectrometriadeFluorescênciaAtômica de Vapor Frio]

Abstract

This work presents the validation of an analytical method for determining the lip fraction of Hg in water bottles. One proposal was reduced in reducing the temperature of glass fiber glass filters (0.7 μm GF / F), so that there was no loss of Hg. After the digestion step with concentrated HNO3 (EPA 3051a), as HgL determinations were performed by the direct mercury analyst (DMA), confirm by the comparative method of steam vapor atomic fluorescence spectrometry (CV-AFS). A concentration of HgL applied by the DMA technique ranged from 0.044 to 0.145 ng mL-1, while CV-AFS varied from 0.002 to 0.138 ng mL-1. Regarding recovery, the results obtained for both methods were 113.6% and 107.0%, respectively. An analysis of the results showed that there was no statistically significant difference (p <0.05), showing good accuracy of the technical proposal. The evaluation of the displayed response surface, which measures the total content (TSS), increases, the HgL concentration also increases. ANOVA showed statistical significance when the independent variables were correlated with the content of the TSS (95% level). Thus, as the analyzes that determine the determination of HgL in the TSS of river water are possible via DMA, as long as the boundary conditions (temperature control and cleaning of glassware) are followed. © 2020 Sociedade Brasileira de Quimica. All rights reserved.