Determinação de mercúrio em camarão do estado do Ceará por análise direta empregando espectrometria de absorção atômica por amalgamação de decomposição térmica

Abstract

Mercury (Hg) is a highly teratogenic and carcinogenic non-essential metal, classified as a priority pollutant. Hg is present in the environment both naturally and by anthropogenic origin. Concern about environmental pollution by Hg has intensified the search for analytical methods that require minimal sample preparation and provide good analytical sensitivity. The benthic and detritivorous characteristic of shrimp makes it a possible mercury bioaccumulator and a biomarker of environmental contamination. It is important to analyze Hg, a toxic element, which is generally in low concentration in this type of matrix, which requires a sensitive analytical method for the determination of traces of mercury. The most common analytical methods for Hg analysis are cold vapor atomic absorption spectrometry (CV AAS) and inductively coupled plasma mass spectrometry (ICP-MS), however these techniques require sample preparation before analysis, implying in greater sample handling, which increases the possibility of analytical errors, analyte loss, and also requires a longer analysis time. Thus, direct analysis is an alternative to these techniques, because it eliminates the sample preparation step, reduces the generation of hazardous waste, reduces the possibility of analytical errors, in addition to having less analysis time (on average 8 minutes per sample ). The objective of this work was to determine Hg in shrimp samples using thermal decomposition amalgamation atomic absorption spectrometry (TDA-AAS) by the direct analysis method. In this work, wild (Farfantepenaeus brasiliensis) and farmed (Litopenaeus vannamei) shrimp purchased in the market in northeastern Brazil were studied. The method of analysis applied was U.S. EPA Method 7473 and is described in other works in the literature as a proven alternative to these techniques that require wet sample preparation. The tissue of wild shrimp showed 75.47 µg kg−1 Hg and was the highest concentration of Hg presented in the work, while the lowest concentration of Hg in the work was from the exoskeleton of farm shrimp, which presented a concentration of 3.71 µg kg−1 Hg. However, making a general comparison between all shrimp samples, wild shrimp samples always showed higher concentration of Hg when compared to farm shrimp samples. The method proved to be appropriate according to the Hg analysis, reaching the appropriate quantification limits for the requirements of Brazilian legislation.