Application of Cold Vapor-Atomic Absorption (CVAAS) Spectrophotometry and Inductively Coupled Plasma-Atomic Emission Spectrometry methods for cadmium, mercury and lead analyses of fish samples. Validation of the method of CVAAS

This paper presents the results of the implementation and application of methods for cadmium (Cd), mercury (Hg) and lead (Pb) analyses in fish samples. The determination of elements by Inductively Coupled Plasma-Atomic Emission Spectrometry and Cold Vapor-Atomic Absorption Spectrophotometry (CVAAS) was carried out using calibration curves, prepared from certified stock standard solutions of the elements. A Certified Reference Material (DOLT-2) has been successfully analyzed with CVAAS method. Sample preparation was performed by microwave-assisted acid digestion using a mixture of HNO3, H2O2 concentrated for the determination of Hg and HNO3 with HClO4 for Pb and Cd analyses using platinum vessel for the digestion. Limits of detection and quantitation were at least a factor of ten and five below the Residual Maximum Limit, respectively, showing that the CVAAS technique is well suited for quantitation of elemental impurities of mercury. It was obtained a good linearity with a linear regression coefficients higher than 0.99. An acceptable reproducibility, repeatability and trueness were found, in agreement with “Harmonized guide of method validation and estimation of uncertainty calculation applied to determination of inorganic pollutants” that it was studied in the theoretical course of validation organized by the project RLA 5060, for the validation of CVAAS method in Hg analyses of fish samples. Mercury showed the higher values in fish samples analyzed, finding content below the permissible maximum limits established by the World Health Organization (less than 0.5 μg/g fresh wet weight).