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 proccdure for the determination of Cd in equine muscle tissue with respect to the introduction of a legal limit for Cd in cquine 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 frcsh substance. Limits for the 1% range of crroneous 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.