Estimation of uncertainties of the method to determine the concentrations of Cd, Cu, Fe, Pb, Sn and Zn in tomato paste samples analysed by high resolution ICP-MS.

Cadmium, copper, iron, lead, tin and zinc were determined in tomato paste samples by using high resolution inductively coupled plasma mass spectrometry. This study was a part of Proficiency Testing scheme conducted by National Metrology Institute (UME) of Turkey. The method was validated. The percentage relative errors obtained for each element ranged between 1.4% and 9.0% for NIST SRM 1573a, tomato leaves. Measurement uncertainties of all elements were calculated by applying bottom-up approach. The calculated percentage relative uncertainties for the elements were between 8.2% and 16.4%. The major contributions to the uncertainty budget came from the calibration curves, repeatability and recovery. Tomato paste samples gathered from the supermarkets in Turkey were analysed by using the validated method. Their levels were compared both with the literature values and European Commission Regulations.