What are environmental reference materials?
The matrix of environmental samples is complex, the concentration of pollutants is low, the concentration range of components to be tested is wide, and the stability is poor, which is significantly different from that of single-component samples. Therefore, the single-component standard solution used in the commonly used relative analysis methods will bring large errors. In order to solve this error caused by the matrix effect, since the 1970s, developed countries such as the United States and Japan have begun to develop environmental standard substances. Environmental standard substances refer to substances with complex matrix composition, close to the composition of environmental samples, good uniformity, stability and long-term preservation, which can be determined by a sufficiently accurate method, and the content of components is known. The role of environmental standard substances is mainly reflected in the following four points:
(1) Reference materials, as samples of known composition and content, can be used for monitoring quality control between laboratories and within laboratories.
(2) Due to the similarity in composition, environmental reference materials can be used as the standard for environmental monitoring to eliminate the matrix effect.
(3) Environmental reference materials can be used to calibrate analytical instruments and evaluate the accuracy and precision of monitoring methods.
(4) Environmental reference materials can be used to test the reliability of new methods. At present, the international representative environmental standard materials include the "certified reference materials" of the international standards organization, and the developed country standard materials represented by the "standard reference materials" of the National Bureau of Standards of the United States. Our country currently has a variety of environmental standard materials for gases, water and solids. Our country National Bureau of Standards stipulates that BM is used as the code name of the national standard material, which is divided into national first-level standard materials and ministerial second-level standard materials. Existing environmental standard materials include standard water samples, solid standard materials and standard gases. National first-level standard materials need to meet the following conditions:
(1) It should have a national reference material certificate with a uniform number.
(2) The accuracy of the fixed value should be at the highest level in China.
(3) Use absolute measurement methods or two or more accurate and reliable measurement methods with different principles to determine the value.
(4) The stabilization period should be more than one year.
(5) It should ensure that its uniformity is within the precision range of the fixed value;
(6) It should have the required qualified packaging form.
