Comment submitted by Ralph Schulz, EDP Laboratory, Georgia Department of Natural Resources

Having performed UCMR-1 and UCMR-2 I would ask that the Quality Control objectives allow for a recovery above method limits in the opening Initial Calibration Verification and the final Closing Calibration Verification of a sequence if no UCMR-3 target compounds are detected in any field samples run in the sequence. The instrument has been shown to be "Bias High" but with no detects in the field samples the data should be considered valid. However if the Fortified Field Sample is run the initial CCV must pass. A "Bias High" surrogate recovery in a field sample should also be allowed if there are no detects in the field sample and the data should be valid. If a Fortified Field Sample is to reflect true recovery values obtained in the analysis then any failures should be accepted and not questioned, especially if LFB data is valid and within QC objectives to support a valid extraction. Fortified Field Samples, even drinking water samples used for UCMR are not Pure Filtered Laboratory Water Samples and react in an unexpected manner. Recovery failures with these Fortified Field Samples happen and must be accepted if the LFB is valid.