Validation of an inductively coupled plasma-optical emission spectrometry method for the determination of major elements in farmed rainbow trout ( Oncorhynchus mykiss )

An inductively coupled plasma−optical emission spectrometry method was optimized and validated for the determination of major elements (Ca, K, Mg, Na and P) in cultivated freshwater fish (rainbow trout Oncorhynchus mykiss ). The method was validated by analysis of a Certified Reference Material, consisting in a frozen tissue homogenate from lake trout ( Salvelinus namaycush namaycush ). The linearity of this method was very good, as evidenced by the coefficients of correlation ( r ) for calibration graphs that were higher than 0.9999 in all cases and by linearity test (response factor <5% and relative calibration graph slope <2%). Accuracy, expressed as relative recovery (%) in comparison with certified concentration ranged from 100 to 109%, and precision, expressed as residual standard deviation (%) ranged from 1.2 to 6.5% (repeatability) and from 1.0 to 9.6% (reproducibility). The limit of quantification ranged from 4 ng/mL (Ca and Mg) to 203 ng/mL (P). The optimized method was applied to major element determination in skin and muscle samples from rainbow trout fillets.