Section 1: Introduction

Polychlorinated dibenzo-para-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are now known to be widespread environmental contaminants. They are found in such diverse matrices as industrial effluent, soil, sediment, water, ash, tissue, and ambient air samples. The detection limits reported for these toxic substances are generally in the low ppt to ppq range. It is clearly important that analytical data corresponding to such ultratrace levels be of definable and verifiable quality.

The objective of this report is to promote the generation of PCDD/PCDF data of consistently high quality by:

1. specifying the essential elements of a Quality Assurance (QA) program that all laboratories generating PCDD/PCDF data in support of federal government programs will be expected to implement as a basic minimum;
   
2. establishing criteria that both laboratory analysts and program managers can use to assess data produced;
   
3. specifying the documentation that will be necessary for screening assessment of data quality in terms of QA support and performance criteria.

The application of these internal QA guidelines constitutes an essential part of a complete QA program. In this report, it is assumed that the laboratory has already demonstrated satisfactory performance in appropriate interlaboratory performance evaluation studies.

This report is applicable to the analysis of samples using capillary high resolution gas chromatography (HRGC) coupled with either low resolution mass spectrometry (LRMS) or high resolution mass spectrometry (HRMS).

Detailed analytical methods and QA/QC procedures for specific matrices are described in publications listed in the References of this report (DQAC,1989; Environment Canada, 1992; Environment Canada, 1990; U.S. EPA, 1990).