Expert Review Panel for Dietary Supplements

6. Based on the supporting information, what are the cons/weaknesses of the method?

- The major weakness of the method is that baseline separation is not achieved for most of the analytes in the real samples (Appendix 5) and the baseline is not stable in most of the real samples

Sample 063: Only 6-shogaol, 8-shogaol and 10-shogaol peaks are baseline separated

Sample 099: Only zingerone, 6-shogaol, and 8-shogaol peaks are baseline separated

Sample 251: Only 6-shogaol, 6-paradol and 10-shogaol peaks are baseline separated

Sample 420: 10-gingerol is not baseline separated

Sample 580: Only zingerone, 6-shogaol, 8-shogaol and 10-shogaol peaks are baseline separated

Sample 875: Only 6-shogaol and 8-shogaol peaks are baseline separated

Sample 889: Only 6-shogaol, 10-gingerol and 10-shogaol peaks are baseline separated

Sample 986: Only 6-shogaol and 8-shogaol peaks are baseline separated

- I don't agree how the fReference Material Stock (on page 3) were prepared. The concentration of the stock solution is not correct; weighing the standard(s) and add 20 mL methanol doesn't define the final volume of the solution. The correct method to prepare calibration solutions is to weigh the standar(s) into a Class A volumetric flask and dilute to volume. - I have similar problem with the sample preparation (the volume of 60 mg sample + 10 mL diluent is more than 10 mL). In addition, 1 g sample mixed with 10 mL diluent is probably a paste and not a solution.

- There is no description how the softgel capsules were prepared for the analysis

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7. Any general comments about the method?

Well written method with large amount of validation data.

Recommendation for the Method