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3. Is there information
demonstrating that the
method system suitability
tests and controls as
specified in the SMPR worked
appropriately and as
expected? If no, please
specify.
The method lists acceptable tolerances for system check standards, but does not give
examples of actual testing results. System precision was measured for an intermediate
standard, however it is not clear over what period of time this data was acquired.
4. Based on the supporting
information, is the method
written clearly and concisely?
If no, please specify the
needed revisions.
The method is clearly and concisely written, but at the cost of several key details. A
number of generalizations are made regarding the sample preparation and data
interpretation that may have the potential to impact results.
5. Based on the supporting
information, what are the
pros/strengths of the
method?
GC-MS is a highly selective and sensitive analytical technique. Therefore this method
does not suffer from interferences the way some traditional methods for quantitation of
ethanol do. The low limit of detection of this method is very suitable for the quantitation
of low levels of ethanol in kombucha beverages.
6. Based on the supporting
information, what are the
cons/weaknesses of the
method?
There is very little detail of the sample preparation for analysis, which can have a
significant impact on results. Additional details would be beneficial to ensure consistent
results are delivered. Second, the validation data seems to be lacking in detail and
based on interpretation may not meet the SMPR requirements. This is not to say that
the method is not suitable and that this testing has not been completed, rather it was
not included here.
7. Any general comments
about the method?
A Purge and Trap-GC-MS approach is highly suitable for the quantitation of ethanol in
beverages, especially kombucha. This method has strong potential, but the details
missing from the method and supporting information bring into question the level of
development of the method. I would assume the author would be able to provide
additional method and validation details if prompted. Purge and Trap-GC-MS is a
technique commonly used in the environmental community for the quantitation of trace
levels of ethanol in water samples adding credibility to the analytical approach.
Do you recommend this
method be adopted as a First
Action and published in the
Official Methods of Analysis
of AOAC INTERNATIONAL?
Please specify rationale.
Yes, I recommend this method to be adopted as a First Action. The Purge and Trap-
GC-MS technology is highly suitable for the quantitation of ethanol in kombucha, and I
believe that additional inter-laboratory validation will prove its performance. Not all
Method Performance Requirements were expressed in the same vocabulary as the
SMPR, but the method appears to meet nearly all requirements.
Recommendation for the Method