Desenvolvimento e validação de método analítico para determinação de nutrientes e contaminantes em pescados do baixo rio São Francisco utilizando técnicas de plasma

Abstract

DEVELOPMENT AND VALIDATION OF AN ANALYTICAL METHOD FOR DETERMINING NUTRIENTS AND CONTAMINANTS IN FISH FROM THE LOWER SÃO FRANCISCO RIVER USING PLASMA TECHNIQUES. The Lower São Francisco (BSF) region, which includes areas of Alagoas, Sergipe, Bahia, and Pernambuco, plays an essential role in socioeconomic development and the preservation of local culture. However, the impacts arising from human activities can cause the bioaccumulation of harmful substances, such as potentially toxic elements, in aquatic organisms and biomagnification along the food chain. Monitoring water parameters of ichthyofauna and flora is essential to assess environmental impacts, identify reliable bioindicators, ensure food security, and support sustainable management policies. This study developed and validated an analytical methodology suitable for the determination of nutrients and inorganic contaminants in fish collected in the BSF by microwave-induced plasma optical emission spectrometry (MIP OES) and inductively coupled plasma mass spectrometry (ICP-MS). The optimal digestion and determination conditions were established, which included the determination of the limits of detection (LOD), quantification (LOQ), linearity, precision, and accuracy, using certified reference materials and addition and recovery assays. Iron, Zn, Cr, Cu, V, Ni, Co, Mo, Mn, Se, Sr, As, Cd, Hg, and P were determined by ICP-MS and Ca, K, Mg and P by MIP OES in 136 samples collected in two stations, over 12 months. The Pb, Ni, Mo, Cd, Cr, Co, and V levels were < LOD in all samples evaluated. For the summer, the determined contents indicated the following variations: Ca (0.1−2.8 g kg⁻¹), K (1−8 g kg⁻¹), Mg (0.1−0.6 g kg⁻¹), P (0.6−5 g kg⁻¹), Fe (0.7−15 mg kg⁻¹), Zn (0.9−12 mg kg⁻¹), Se (0.1−0.6 mg kg⁻¹), Sr (0.1−5 mg kg⁻¹), Cu (0.1−9.2 mg kg⁻¹), Mn (0.1−2 mg kg⁻¹) and As (0.1−5 mg kg⁻¹). For winter, Ca (0.1−2 g kg⁻¹), K (1−7 g kg⁻¹), Mg (0.2−0.4 g kg⁻¹), P (0.5−5 g kg⁻¹), Fe (0.3−10 mg kg⁻¹), Zn (0.4−20 mg kg⁻¹), Se (0.1−0.6 mg kg⁻¹), Sr (0.1−6 mg kg⁻¹), Mn (0.1−3 mg kg⁻¹), As (0.1−4 mg kg⁻¹) and Cu (0.1−0.3 mg kg⁻¹). For the first time, the mineral profile of BSF fish was obtained, indicating satisfactory nutrient levels per the daily consumption recommendations and contaminants below the limits established by legislation.