Validação da determinação de macro e micronutrientes em ração de peixes por espectrometria de emissão óptica com plasma induzido por micro-ondas (MIP OES)

Abstract

The work with analytical methodologies has acquired great relevance and target of high demand in research and agricultural development. Thus, this work seeks to offer detailed options in fish feeding monitoring studies. First, a methodology for preparing samples was proposed. The lack or abundance of some nutrients can cause damage to the animal and the production chain of the psychoculture. Despite the existence of other procedures, the defined digestion method employed 150 mg of analyte, weighed directly in the vials of modified PTFE, then added 3.0 mL of HNO3, 2.0 mL of H2O2 30% (m/m) and 3.0 mL of H2O to digest the fish feed specimens to determine macro and micronutrients. After the digests the final solution was soured to 30 mL with water. The nutrient reading process was performed by microwave-induced plasma optical emission spectrometry (MIP OES). The veracity, verified with the use of MR and addition and recovery tests, presented values between 82 and 108%. The results of mass fractions of Ca, Mg, K, P, Fe, Cu, Mn, Zn and Na found in the fish feed samples analyzed are: 17.38 g kg-1 P; 26.30 g kg-1 Ca; 5.79 g kg-1 K; 1.6 g kg-1 Mg; 1.89 g kg-1 Na; 106.81 mg kg-1 Zn; 197.93 mg kg-1 Fe; 9.05 mg kg-1 Cu; After preparing and determining, the stage of validating the methodology to quantify and detect macro and micronutrients by MIP OES was performed. The study presented satisfactory linearity when analyzing its r2 values. On the other hand, the selectivity analyzed in the study, when related to the matrix effects obtained satisfactory results. The limits of detection and quantification obtained were, respectively, 0.001 mg kg -1 and 0.005 mg kg -1. The results show that the validation procedure is of paramount importance for the maintenance and monitoring of fish diets. In addition, microwave-induced plasma optical emission spectrometry (MIP OES) is an economical alternative in nutrient analysis in fish feed. Despite the nutritional importance, the presentation of the contents of other inorganic nutrients by manufacturers is not required by legislation.