Optimization of sample preparation procedures for evaluation of the mineral composition of fish feeds using ICP-based methods.

This work describes the application of an experimental design in optimizing the decomposition and spectrometer operational conditions for analysis of fish feeds. The content of 22 elements (six macroelements, four microelements and eleven trace elements) in feeds for fishes (ornamental and for human consumption) was determined by inductively coupled plasma (ICP)-based methods. Limits of quantification were obtained and the values ranged between 0.02 mg kg-1 (Cd) and 76 mg kg-1 (Al). Evaluation of the methods was achieved through analysis of standard reference material, Oyster Tissue (NIST 1566b) and Tea (NCS DC 73351). Element concentrations in feed samples for ornamental fish ranged from <0.02 mg kg-1 (Cd) to 2.79% (P) and for fish breeding for human consumption from <0.02 mg kg-1 (Cd) to 2.00% (Ca). The concentrations of the elements obtained in the analyzed fish feeds were within the limits established by Brazilian and American legislation for regulated elements.