Dispersive liquid-liquid microextraction as a preconcentration alternative to increase ETAAS sensitivity in the analysis of molybdenum in bovine meat and pasture samples.

A new procedure combining dispersive liquid-liquid microextraction and electrothermal atomic absorption spectrometry was proposed for the determination of molybdenum in plants and animal tissue. The optimized conditions for the microextraction procedure were: 150 μL of 0.3 mol L-1 potassium ethyl xanthate (pH 1.4) and 1000 μL of acetonitrile and 50 μL of carbon tetrachloride as dispersive and extractant solvent, respectively. A limit of detection of 0.03 μg kg-1 and a limit of quantification of 0.11 μg kg-1, as well as an enrichment factor of 200, were achieved employing this procedure. Standard reference materials were used for trueness and precision evaluation. No significant differences were found at the 95% confidence level between certified and obtained values, and the precision expressed as repeatability (sr %) was 4.1% for animal tissue and 4.7% for plant material. The method was successfully applied for the determination of Mo in bovine meat and pasture samples from different livestock establishments.