Double-blind performance evaluation (PE) samples are introduced into field sampling batches. Samples are introduced in a manner whereby the contract analytical laboratory is unaware of either the nature of the sample (i.e., a PE sample) or of its component concentrations, thus preventing “special” treatment of PE samples.

Double-blind PE samples, created from bulk materials, groundwater, surface water, or soils collected from near the sampling areas, mimic routine field samples in both matrix and contaminant concentrations. PE samples are prepared in the following matrices:

• Groundwater,
• Surface water, and
• Soil

Bulk materials have been certified for background concentrations by an independent laboratory. A sample aliquot is spiked with radiological, inorganic, or organic traceable standards.

After preparation, PE samples are sent by courier to the field sampling location where they are inserted into the field batch with other samples and sent to the laboratory for analysis. PE sample packaging and labels are identical to the field samples to ensure that they are not identified as PE samples by the commercial laboratory. PE samples are then analyzed by the laboratory along with ordinary samples; results of PE sample analyses are therefore useful in evaluating the commercial laboratory’s performance as a whole.

PE analytical results from the commercial laboratory are evaluated against documented values. Comparison studies help ensure that accurate, reliable, high-quality data are received from the commercial analytical laboratories.

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