Comprehensive Stability Study of the Substances and Metrological Characteristics of Certified Reference Materials of Lake Baikal Bottom Silt and Sediments (BIL-1 and BIL-2)

The requirements of regulatory acts, issued by the Federal Agency on Technical Regulation and Metrology (Rosstandart) regulate the using the certified reference materials (CRMs) in accordance with their expiration dates and validity and envisage the procedures to confirm the certified metrological characteristics after the their production. In the period from 1989 to 1995, the A. P. Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, developed as single batches two multielement CRMs: Lake Baikal bottom silt (BIL-1 – GSO 7126-94) and Lake Baikal bottom sediments (BIL-2 – GSO 7176-95). For these CRMs, the metrological characteristics of 49 and 30 elements and components, respectively, have been certified, so for more than 30 years they have used as material patterns of bottom substance in chemical analysis and analytical control procedures. The present study focuses on summarizing the previously obtained and new data about the mineral and granulometric compositions, homogeneity of powders of each CRM as the basis for the stability of their certified metrological characteristics. New data on the mineral and granulometric compositions of these CRMs are in good agreement with the previously obtained data. Besides, the distribution homogeneity of 33 elements in the powders of CRMs, and the smallest representative probes for the same elements were evaluated experimentally; for remaining elements/components these parameters were assessed by the indicator elements. The stability of the certified metrological characteristics of the elemental composition of these CRMs, under conditions of natural aging, has also been demonstrated through statistical processing of measurements obtained by various analytical methods and techniques over the long-times. The shelf lives and validities for the targeted use of BIL-1 and BIL-2 CRMs, being unique in terms of their information content, having no analogues in Russia and being in demand in the field of state regulation to ensure uniformity of measurements in chemical analysis of sedimentary substance, have been extended.