ABSTRACT
National and international organizations such as International Standardization Organization, International Union of Pure and Applied Chemistry (IUPAC), have compiled information listing approximately 100,000 SRMs of different types. The number of certified standard reference materials (SRMs) is much less. Cali’s report gives more accurate figures, presenting a listing of 967 SRMs that are available from the National Bureau of Standards. Out of approximately 5000 items in IUPAC compilation dealing with SRMs for trace analysis, only 22 can be considered valid for environmental analysis, and 16 of them are gases. Although the number of certified standard samples is increasing significantly, it is impossible to provide SRMs for many of the different types of materials, analytical problems, and methods that the environmental analyst encounters. The calibration, testing, and checking can be done by the following methods: Use of certified natural standards, Use of synthetic standards, Use of independently analyzed samples, Use of standard addition and internal standards and Use of fundamental relationships.
