SPDS EXPERT REVIEW PANEL

B. Does the method contain system suitability tests or controls as specified by the SMPR? If not, please indicate if there is a need for such tests or controls and which ones. C. 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. D. Based on the supporting information, is the method written clearly and concisely? If no, please specify the needed revisions.

YES, partially. In the manuscript, the system suitability test was performed by making 5 replicate injections of the check standard at the lowest point of the analytical range. However, SMPR also requires a check standard with the middle point of the analytical range, a blank sample, and a control sample for system suitability tests, while the manuscript does not provide such tests.

YES, partially. Same procedure was performed as described in manuscript.

YES. Overall, the method is written clearly and concisely. However, some descriptions may be oversimplified. For example, it cannot follow how are the different concentrations of mixed calibration standard solutions were made from the individual standard stock solutions without reading the original publications. In the determination of analytical range, the manuscript claimed that the analytical range tested for each analyte was up to 1000 µg/mL. No testing data were presented in the manuscript or supporting documents. No sonication is involved in sample preparation, while ultrasonic bath is listed in the section of Apparatus. Good resolution of the five analytes of interest is achieved under the HPLC chromatographic condition in all the three Echinacea spp. The sample preparation is straight forward and was optimized for the sample weight, particle size, extraction solvent, ratio, and extraction efficiency. The method demonstrated good precision and also the recoveries from both blank and plant matrixes for the five phenolic compounds. Analytes were stable in the use of extraction condition and course of analysis. The method is not suitable for the analysis of the proposed analytes in glycerite tincture. The LOQs for some compounds were higher than SMPR, e.g. 0.036% for echinacoside, while SMPR is not more than 0.01%. Sample size for raw materials (125mg) might be too small and may affect precision analysis. Use of guard column was not included in method validation. The manuscript presents a typical HPLC method and is a summary of the method validation date from two SLVs and one interlaboratory collaborative study. The method allows for the determination of five major phenolic compounds in three Echinacea species and is applicable to raw materials, extracts and dietary supplements and most commonly used dosage forms found in marketplace. The data collected from SLVs and collaborative study meets most SMPR criteria.

E. Based on the supporting information, what are the pros/strengths of the method?

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

G. Any general comments about the method?

Recommendation for the Method