Frequent Questions

Instrument performance checks for SW-846 Methods 8260 and 8270.

Is a traditional DFTPP or BFB tune in full scan mode required for SIM analysis?

We know the 8270 GC performance and inlet inertness checks are not required but would they even provide value at all during a SIM analysis as a recommendation?

 

Instrument performance checks (including tune verification) are still important quality assurance elements in the new revisions of 8260D and 8270E, even for method applications not based on full mass range acquisition like selected ion monitoring (single quadrupole mass spectrometry) or multiple reaction monitoring (ion trap or triple quadrupole mass spectrometry).

Tune checks include verification of mass assignments and mass resolution, which are important considerations for quantitative analysis under all of these conditions.  8260 and 8270 require a tune check to be performed prior to analysis (note the use of the word "must" in Section 7.3.1 in 8260B, 8260C and 8270C and Sections 11.3.1 and 11.4.1 in 8270D). However, 8260D and 8270E method revisions incorporate some additional flexibility with respect to demonstrating appropriate optimization of MS settings by allowing the operator to meet the MS instrument manufacturer’s performance criteria or alternative documented ion ratio criteria for DFTPP or BFB.

Degradation checks and tailing factor checks in Method 8270 are used to minimize problems with measurement of sensitive target analytes as the system becomes contaminated with non-volatile material and as the deactivated coating is stripped off of the chromatographic system.   However, these performance checks are not recommended for all method applications in 8270E; exceptions are noted for analyte classes not known to be affected by the same types of inlet reactivity or chromatography issues, like polycyclic aromatic hydrocarbons and polychlorinated biphenyls.  Nevertheless, when testing for analytes that are known to be sensitive to inlet reactivity and/or column inertness, these additional quality controls may provide important indications of changes in sensitivity or reactivity specific to certain analytes that may help the laboratory identify quality assurance issues with respect to sensitivity and/or analyte identification that may not otherwise be apparent. Since the methods are published as guidance, it is the responsibility of the laboratory in conjunction with the data user and other stakeholders to determine whether omitting this type of quality control check is acceptable for a specific data application.

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