Psittaciformes mineral feed analysis method choice and optimization employing chemometric tools

Abstract

BackgroundIn this work, a multivariated approach based on factorial design and principal component analysis was used to perform the optimization of sample decomposition. The method was applied for the first time to quantify several chemical elements (Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, P, Pb, Se and Zn) in Psittaciformes feed. The choice of the best sample decomposition method is a challenging task considering all variables involved in the process. Generally, this choice is made by using individual monovariated experiments and sometimes interaction effects between these variables as mass of the sample, acid composition, temperature, etc, are not considered. MethodsSample decomposition: 200 mg of sample was mixed with 3.5 mL of HNO3 65% and left at room temperature for 24 h, in a pre-decomposition step, heated at 150 °C for 50 minutes employing a digestion block and mixed with 1.5 mL of H2O2 in the last ten minutes of decomposition. Chemical analysis: A total of 44 samples of Psittaciformes feed digests, among extruded feed, flour and snacks), purchased at pet stores or similar stores in six states in Brazil, were analyzed by inductively coupled plasma optical emission spectrometry (ICP OES). Method accuracy was assessed using certified reference materials SRM 1567a, SRM 1573a, SRM 1577b and IMEP 19. ResultsThe limits of detection (LoD) and quantification (LoQ) ranged from 0.02 mg kg−1 to 0.07 mg kg−1 (Se) and from 1.79 mg kg−1 to 5.41 mg.kg−1 (Ca), respectively. The concentration of chemical elements in animal food ranged from <0.27 mgkg −1 (Fe) to 41.4 ± 2.9 g kg−1 (P), in flour concentrations ranged from <0.05 mg kg−1 (Mg) to 23.8 ± 4.1 g kg−1 (P) and concentrations ranged from <0.05 mg kg−1 (Mn) to 6.8 ± 0.9 g kg−1 (Ca) in snacks. ConclusionThe approach based on multivariate analysis to perform a sample decomposition was successfully applied for Psittaciformes feed. In general, the chemical elements listed on the product labels (Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, P, Pb, Se and Zn) were detected at variable contents when compared to the recommender nutritional values. Toxic elements, Cd and Pb were not detected in any of the analyzed samples. The detection and quantification of chemical elements not listed in nutritional tables and in each product label indicates that mineral addition by manufacturers is performed without considering the chemical composition of the raw materials used in the production process, which can lead to nutritional issues. Thus, a broad revision of Brazilian Legislation concerning product classification considering quality and mineral addition criteria in daily animal feed, especially pets, is urgently required.