Development of Kudzu (Pueraria Montana var. lobata) Reference Materials for the Determination of Isoflavones and Toxic Elements.

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 kudzurmaterials 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 matrixes for use by dietary supplement manufacturers for the verification of the safety of their raw materials.

Effects of elevated temperature and mobile phase composition on a novel C18 silica column.

A novel polydentate C18 silica column was evaluated at an elevated temperature under acidic, basic, and neutral mobile phase conditions using ACN and methanol as the mobile phase organic modifier. The temperature range was 40-200 degrees C. The mobile phase compositions were from 0 to 80% organic-aqueous v/v and the mobile phase pH levels were between 2 and 12. The maximum operating temperature of the column was affected by the amount and type of organic modifier used in the mobile phase. Under neutral conditions, the column showed good column thermal stability at temperatures ranging between 120 and 200 degrees C in methanol-water and ACN-water solvent systems. At pH 2 and 3, the column performed well up to about 160 degrees C at two fixed ACN-buffer compositions. Under basic conditions at elevated temperatures, the column material deteriorated more quickly, but still remained stable up to 100 degrees C at pH 9 and 60 degrees C at pH 10. The results of this study indicate that this novel C18 silica-based column represents a significant advancement in RPLC column technology with enhanced thermal and pH stability when compared to traditional bonded phase silica columns.