LAUSR

BACKGROUND In collaboration with the Office of Dietary Supplements at the National Institutes of Health, the National Institute of Standards and Technology issued a suite of botanical matrix Reference Materials (RMs) and Standard Reference Material® (SRM) for determination of isoflavones and toxic elements in kudzu dietary supplement ingredients. OBJECTIVE RM 8650 Pueraria montana var. lobata (Kudzu) Rhizome, SRM 3268 Pueraria montana var. lobata (Kudzu) Extract, and RM 8652 Kudzu-Containing Solid Oral Dosage Form were issued with values assigned for isoflavones (puerarin, daidzin, and daidzein), toxic elements (arsenic, cadmium, and lead), and selenium. METHODS Isoflavone values were assigned using liquid chromatography with UV absorbance or mass spectrometry detection. Element values were assigned using inductively coupled plasma mass spectrometry and results from an interlaboratory comparison exercise. RESULTS Mass fractions for puerarin were (32.2 ± 3.2) mg/g, (128 ± 13) mg/g, and (68.2 ± 6.9) mg/g in RM 8650, SRM 3268, and RM 8652, respectively. Arsenic increases from (156 ± 14) ng/g to (849 ± 83) ng/g and cadmium decreases from (348 ± 14) ng/g to (82.1 ± 4.9) ng/g from rhizome to extract. CONCLUSION The kudzu RM/SRM suite complements previously issued soy-related SRMs with values assigned for isoflavones, which have been studied for their potential health benefits, and expands the analytical resource by providing values for puerarin, an isoflavone not found in soy. HIGHLIGHTS The three new kudzu materials are for use in the determination of isoflavones, toxic elements, and selenium. For the isoflavones, these new kudzu materials provide higher levels of daidzin and daidzein than existing soy-related SRMs, and they provide a value for an isoflavone not in existing SRMs (puerarin). Toxic elements in RM 8650 and SRM 3268 provide new botanical matrices for use by dietary supplement manufacturers for the verification of the safety of their raw materials.