Expert Review Panel for Kombucha Tea

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. 4. Based on the supporting information, is the method written clearly and concisely? If no, please specify the needed revisions. 5. Based on the supporting information, what are the pros/strengths of the method? 6. Based on the supporting information, what are the cons/weaknesses of the method?

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.

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.

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. 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. 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.

7. Any general comments about the method?

Recommendation for the Method

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.