Biological activity measurements accuracy

The role of transportation sources in the emissions of PAH-POM is not known with accuracy, especially as biologically active POM is concerned. One participating research group cites mobile sources in Scandinavia as contributing 6 to 9% of the total atmospheric PAH, and around 24% in the U.S., although the data base used for the U.S. was not corrected for the use of catalytic convertors. Such estimates should be measured for the local urban environment rather than a national or continental scale which is subject to great variances. 

Information for the description of the receptor are given as a set of experimental biological activities, Ai, corresponding to molecules Mi, i = 1,N. It is supposed that the biological activities are measured in the same conditions for all the M compounds, with the same accuracy and precision. 

National Institute of Standards and Technology (NIST). The NIST is the source of many of the standards used in chemical and physical analyses in the United States and throughout the world. The standards prepared and distributed by the NIST are used to caUbrate measurement systems and to provide a central basis for uniformity and accuracy of measurement. At present, over 1200 Standard Reference Materials (SRMs) are available and are described by the NIST (15). Included are many steels, nonferrous alloys, high purity metals, primary standards for use in volumetric analysis, microchemical standards, clinical laboratory standards, biological material certified for trace elements, environmental standards, trace element standards, ion-activity standards (for pH and ion-selective electrodes), freezing and melting point standards, colorimetry standards, optical standards, radioactivity standards, particle-size standards, and density standards. Certificates are issued with the standard reference materials showing values for the parameters that have been determined. 

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