When using methods that employ second column confirmation, which value should the laboratory report (Table B-2)?
EDQW Response: Table B-2 of the QSM states “Report the higher of two confirmed results unless overlapping peaks are causing erroneously high results, then report the unaffected result and document in the case narrative.” Therefore, unless directed otherwise by project documentation, the higher result is to be reported for each analyte (as is specified in the QSM), along with QC appropriate to support the result (whichever column generated it). For methods for which confirmatory column analyses often do not achieve full resolution of all target analyte peaks (i.e. 8330), reporting the result from primary column (whether higher or lower) is preferred when co-elution actually occurs. In these cases, special care needs to be taken to ensure that an analyte has been qualitatively confirmed before it is reported. In cases where co-elution causes the 40% RPD criteria to be exceeded, the result from the primary column should be reported as estimated.
