Influence of the Correction for Moisture/Water Content on the Quality of the Certification of Cd, Cu and Pb Mass Fractions in Rice

Property of certified reference values are very often related to dry mass. The dry mass is determined by measuring the moisture content of the sample. Comparison of 19 IMEP focuses on the evaluation of the highy hygroscopic. Thus, two series of certification were carried out in parallel. First on a set of water "saturated" samples only corrected for their moisture content, and second on a set of "non saturated" samples alo corrected for moisture pick-up occurring before the gravimetric addition of the IDMS isotopically enriched spikes. After critical evaluation of the factors influencing results for moisture in rice sample, the application of three different methods was investigated: oven drying method, Karl Fischer titiration and thermo-gravimetry and obtained results compared. For each of the certified amount contents in the "saturated" and "non-saturated" samples combined uncertainties attached to the measurement results were evaluated according to ISO GUM guidelines, using the uncertainty propagation procedure. The contribution of moisture and hygroscopic determination to the total combined measurement uncertainty is discussed.

VASSILEVA Emilia;  QUETEL Christophe; 

2007-12-13

ELSEVIER SCI LTD

JRC35332

0308-8146,   

https://publications.jrc.ec.europa.eu/repository/handle/JRC35332,   

10.1016/j.foodchem.2007.02.048,