Direct solid sampling ETAAS determination of cadmium in equine muscle

Abstract

Direct solid sampling by means of electrothermal atomic absorption spectrometry (ETAAS) was evaluated as a rapid procedure for the determination of Cd in equine muscle tissue with respect to the introduction of a legal limit for Cd in equine muscle tissue in Germany. Analysis of the distribution of Cd within individual muscles of horses showed the variance component `heterogeneity' (relative standard deviation, RSD: 16%)to be clearly dominated by residual analytical variance (RSD 24%). Error of mean value estimation can be reduced by increasing the number of samples-each taken from different sampling sites-from approximately 30% (n=1) to 11% (n=6) . In a comparison between solid sampling ETAAS and a conventional compound procedure as reference (regression analysis, n=394), the Cd content ranged from 0.01 to 0.9 µg g ^–1 fresh substance. Results were found to be closely correlated (r=0.98) and proved to be analytically and statistically (P>0.10) of no relevant difference. Ranges of erroneous classification were calculated, which allow the identification of transgressing samples. For the legal limit of 0.2 µg g ^–1 fresh substance, erroneous classification (false positive and false negative) ranged from 0.14 to 0.27 µg g ^–1 fresh substance. Limits for the 1% range of erroneous classification were calculated to range from 0.13 to 0.32 µg g ^–1 fresh substance. Based on these results, a model strategy is proposed for the application of direct solid sampling analysis as a rapid in-process screening procedure within the scope of meat hygiene regulations.