Preparation of candidate reference materials for trimethyl-lead analysis and assessment of their homogeneity and stability

Abstract

This study was conducted to develop certified reference materials containing trimethyl-lead (TriML) in environmental matrices. A detailed description of the process to prepare candidate artificial rainwater and road dust reference materials, which includes pretreatment, homogenization and bottling procedures, is described. The homogeneity was assessed by comparing the variations within a bottle and between different bottles. The results demonstrated that the distribution of TriML in the same material is homogeneous. The stability of TriML in these materials was verified on the day of preparation and after 1, 3, 6 and 12 months. The results showed no significant difference between the initial TriML concentration and the concentration after 12 months' storage in candidate artificial rainwater kept at room temperature and in road dust stored at -20°C and 4 °C, based on a statistical analysis of the results. At 37 °C, however, TriML was shown to be unstable: this highlighted the need to store the materials in the dark, preferably at 4°C. TriML in both of the candidate reference materials was hence concluded to be stable for at least 12 months under the appropriate storage conditions.