ABSTRACT

The studies on the analytical procedure for mercury determination in food of plant origin on the level of 5 Mg/kg, were carried out. For this reason, microwave digestion with HNO₃ and cold vapour atomic absorption spectrometry (CVAAS) with tin (II) chloride reduction, were used. Both digestion and determination conditions were experimentally optimized. The procedure was checked using two real food samples: apple juice and preserved carrot with peas both spiked on two levels with mercury. On these results basic statistic parameters that charcterized the method as standard deviation, relative standard deviation and recovery, were calculated. The precision was generally better than 10%, and recovery ranged from 96 to 100%. The detection limit of the entire procedure, defined as the mercury concentration corresponding to three times the standard deviation of ten consecutive determinations of blank measurement, was 0,012 µg/I. Taking into account the amount of a sample and the factor of dilution the detection limit corresponds to 0,3 µg/kg for 1,0 g, 1,0 µg/kg for 0,3 g, and 0,15 µg/l for 2 ml of a sample. Accuracy of the analytical procedure was tested by analysing five certified reference plant materials with the mercury contents ranged from 6 to 280 µg/kg. The obtained results were in a good agreement with their certified values. Both analyses of the spiked real samples and certified reference materials allow to suggest that this analytical procedure based on microwave digestion and cold vapour determination using Fully Automated Mercury System is suitable for mercury determination in food products of plant origin on the level of µg/kg or Mg/1, with a good precision and accuracy.