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and capsules submitted as single materials, data were evaluated only by their HorRat r values. Results with a HorRat value between 0.5 and 2.0 were considered reproducible. The calculated HorRat values were high (>2) for the protopanaxadiols in the finished products and Rb 2 in P. quiquefolius raw materials (Table 5). The poor precision observed for the protopanaxadiols may be due incomplete hydrolysis of the malonyl ginsenosides as these finished products were not subjected to the hydrolysis step in this study. The assumption that finished products would not require hydrolysis needs to be re-evaluated. Rb 2 levels in P. quinquefolius raw materials and in P. ginseng spiked matrix blanks were low, and this may have contributed to the low precision observed with this analyte. The reported laboratory results for each sample matrix are shown in Table 6. Statistical data from the interlaboratory study are shown in Table 7. Data for total ginsenosides in the whole root, powdered extract, and negative spiked matrix blank sample for both P. ginseng and P. quinquefolius provided acceptable results in the interlaboratory study (Table 7). The RSD R ranged from 4.39 to 5.93%, and the calculated HorRat R values were within acceptable limits, ranging from 1.5 to 1.9. However, both finished products were considered inconsistently reproducible because their calculated HorRat r values were greater than 2.0. The capsule and tablet samples had HorRat r values of 2.9 and 3.5, respectively. Based on the results of the interlaboratory study, it is recommended that the method be considered as an AOAC Official First Action for analysis of total ginsenosides in raw materials and powdered extracts. The method can only be considered applicable for analyzing total ginsenosides in the samples as some of the individual ginsenosides exhibited low precision. While it had been suggested that during the manufacturing process the malonyl ginsenosides would be converted to their neutral counterparts, our results suggest this might not be the case, and failure to force the conversion to completion may have resulted in variation of results across the participating laboratories. For finished products made from nonextract root materials it is recommended that future interlaboratory studies include preparing the sample with the inclusion of the basic hydrolysis. This study was funded in part by the Investment Agriculture Foundation of British Columbia, Canada, through the Agri- Food Futures Fund, a provincial trust funded from money under the former federal-provincial safety nets framework and the Office of Dietary Supplements, National Institutes of Health. We would like to acknowledge the following contributors and collaborators for participating in the study: Teresa Cain, FDA Pacific Regional Laboratory Southwest, Irvine, CA Gordon Huie, Natural Factors R & D Laboratories, Burnaby, BC, Canada Chang Dong Jin, Labs-mart Inc., Edmonton, AB, Canada James Neal Kababick, Flora Research Laboratories, Grant Pass, OR Recommendations Acknowledgments

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