Supplement Internal Quality Control

Theoretically IQC should be the front-line approach to quality. If a method has been adequately validated and shown to meet the requirements of the user and kept in analytical control with IQC to detect intrusion of bias or imprecision, then the EQA needs to provide the occasional, independent, objective reassurance. In practice however, the EQA is likely to play an equal role with IQC, both in confirming problems brought to the attention of the analyst by the IQC and in stimulating further action. 

An unexpected outcome from EQA observations appeared when unsatisfactory material was unknowingly used at one time for the manufacture of atomic absorption graphite furnaces. Several laboratories were aware of unsatisfactory IQC for their blood lead methods and strived to find an explanation but it was only when the FQA data revealed a widespread problem that a group of participants compared their recent experience and were able to confirm with the suppliers that inferior graphite had been employed. 

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To supplement internal quality control within a laboratory. 

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