Database of natural matrix reference materials (NMRM) for organic constituents

The International Atomic Energy Agency maintains a database of internationa lly available certified reference materials (CRM) of natural matrices. This database is periodically updated, and presently documents nearly 25,000 me asurands in 1700 materials. Tile organic constituents are classified in fiv e major groups of analytes aliphatic and aromatic hydrocarbons (A), chlorin ated hydrocarbons (B), pesticides (C), organometallic compounds (D) and oth er organic constituents (nutrients, etc.) (E). The matrices include natural materials such as body fluids, food products, soils, and sediments, terres trial (e.g. plants), and anthropogenic products (e.g. dust, fly ash). These five organic groups of analytes encompass more than 2000 measurands for 42 0 different analytes in 230 materials. Of these measurands, 1682 (68%) are certified, and 768 (32%) are provided as informational values. Within each major group of analytes, measurands reported as informational values accoun ted for: A (35%); B (35%); C (26%); D (10%), and E (22%). The high proporti on of informational values (i.e, non-certified values) for A, B, and C, com pares well with a similar but undesirable situation faced in the nineteen-s eventies in the inorganic area when simultaneous multielement techniques be came available. In the case of D and E, it appears that mostly targeted ana lytes are measured, leading to a cohesive certification profile. Although t he IAEA database is not equally comprehensive for all groups of analytes ci ted above, it can still serve as an useful indicator of the status of organ ic constituents in RMs.