Abstract
The need of certified reference materials (CRMs) is consistently growing due to various aspects in the environment and communities. A research project on the production of seven environmental CRMs with international collaboration has been proposed as a pilot study. The CRMs are intended to be applied for quality assurance of toxicological, environmental, and food analyses of matrices of soil, sediment, dust, leaves, date fruit, and edible fish muscle for some elements at macro-, micro-, and trace-levels. This article demonstrates stability tests, as an essential parameter for CRMs, of element content in CRMs using ICP OES and ICP-SFMS. Useful and simple approaches were proposed for stability assessment. Cluster analysis of stability revealed that Cu, Fe, Mn, and Al in CRMs of soil matrices were the most similar elements in term of stability; and likewise for Cu, Fe, and Mn in CRMs of biological matrices. An overall stability of all elements in each CRM was also assessed by paired samples t-test at confidence interval of 95%. The p values of all CRMs are all >.05 indicating no significant variation on elements contents before and after underwent storage, besides limited transport conditions. Despite this study presents a simple way for assessment of stability of elements concentrations in CRMs, further stability studies are required concerning several intervals to study the effect of conditions on stability.