The Quality Assurance (QA) Branch develops, analyzes, and distributes natural matrix samples to evaluate the performance of laboratories conducting analyses for the Office of Solid Waste (OSW). In these studies each laboratory is requested to analyze an organic sample and an inorganic sample using the analytical methods specified by OSW.

The sample designs and reference values are established by multiple analyses in the QA Branch laboratory and contract referee laboratories. These data are evaluated statistically and must be judged acceptable before samples are distributed to the 50–60 RCRA contract laboratories. These data are also furnished to OSW for use in evaluating the results reported by the contract laboratories.