Quality assurance for emissions analysis systems.
The application of quality assurance practices is having a significant, positive impact on the quality of environmental data being generated. One such practice is the performance audit, which involves one laboratory providing ''unknown'' or ''blind'' samples to another laboratory for analysis. A performance audit conducted simultaneously with a source emission sample analysis provides an assessment of analysis accuracy. This accuracy assessment is important for data use in setting standards and for compliance testing after standards have been promulgated. When it has been demonstrated that specific organic gases are stable enough to be used as performance audit materials in the 5-20-ppm concentration range, a performance audit will be included as an integral part of the promulgated test method. Two EPA test methods for vinyl chloride and benzene currently include the requirement for a performance audit during source test analyses. Under a contract to the EPA, the Research Triangle Inst. is developing an extensive repository of gaseous compounds for use in audits a description of which is given in tables. (JMT)