Determinação de arsênio total em amostras de bacalhau por espectrofotometria de absorção molecular

Abstract

Objectives: To determine the concentrations of total arsenic (tAs) in samples of cod and salted cod-type fish, and to verify whether the levels of this chemical element are within the Maximum Tolerance Limit (LMT) of 1 mg tAs/kg of raw fish and /or frozen, provided by the National Health Surveillance Agency (ANVISA). Methods: An experimental study was carried out with samples of cod and salted cod fish obtained from trade in the city of Natal, Rio Grande do Norte (RN). The laboratory analysis was divided into three steps, all performed in duplicate. In the first, the samples were pre-calcined and mineralized at 650 ºC until ash was obtained. In the second stage, the ashes obtained were included in an acid solution to release arsine gas, which in the end complexed with silver diethyldithiocarbamate (DDC-Ag), forming arsenic diethyldithiocarbamate (DDC-As). Finally, the DDC-As solutions were analyzed at 540 nm in a UV-Vis spectrophotometer. To obtain the results, an analytical curve was prepared, also in duplicate, repeating the entire experimental process from the second stage, without adding ash, using a standard solution at 1 μg/mL as an arsenic source. Results: The Atlantic cod, Pacific cod and saithe samples showed 1.131 ± 0.4207 mg of tAs/kg, 1.347 ± 0.1273 mg of tAs/kg and 0.287 ± 0.0660 mg of tAs/kg, respectively. Conclusion: The Atlantic cod and Pacific cod samples are above the LMT recommended by ANVISA, the Saithe samples are within such limits, and are therefore suitable for human consumption in terms of total arsenic content.