title: Optimization and single-laboratory validation of a method for the determination of flavonolignans in milk thistle seeds by high-performance liquid chromatography with ultraviolet detection.
abstract: Seeds of milk thistle, Silybum marianum (L.) Gaertn., are used for treatment and prevention of liver disorders and were identified as a high priority ingredient requiring a validated analytical method. An AOAC International expert panel reviewed existing methods and made recommendations concerning method optimization prior to validation. A series of extraction and separation studies were undertaken on the selected method for determining flavonolignans from milk thistle seeds and finished products to address the review panel recommendations. Once optimized, a single-laboratory validation study was conducted. The method was assessed for repeatability, accuracy, selectivity, LOD, LOQ, analyte stability, and linearity. Flavonolignan content ranged from 1.40 to 52.86% in raw materials and dry finished products and ranged from 36.16 to 1570.7 μg/mL in liquid tinctures. Repeatability for the individual flavonolignans in raw materials and finished products ranged from 1.03 to 9.88% RSDr, with HorRat values between 0.21 and 1.55. Calibration curves for all flavonolignan concentrations had correlation coefficients of >99.8%. The LODs for the flavonolignans ranged from 0.20 to 0.48 μg/mL at 288 nm. Based on the results of this single-laboratory validation, this method is suitable for the quantitation of the six major flavonolignans in milk thistle raw materials and finished products, as well as multicomponent products containing dandelion, schizandra berry, and artichoke extracts. It is recommended that this method be adopted as First Action Official Method status by AOAC International.
authors.affiliation: Natural Health & Food Products Research Group, British Columbia Institute of Technology, 3700 Willingdon Avenue, Burnaby, BC, V5G 3H2, Canada.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Mudge
authors.affiliation: Natural Health & Food Products Research Group, British Columbia Institute of Technology, 3700 Willingdon Avenue, Burnaby, BC, V5G 3H2, Canada.
authors.forename: Lori
authors.initials: L
authors.lastname: Paley
authors.affiliation: 4-10 Agriculture/Forestry Centre, Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, T6G 2P5, Canada.|Institute of Nutritional and Food Sciences, Chair of Food Technology and Food Biotechnology, University of Bonn, Roemerstrasse 164, D-53117, Bonn, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schieber
authors.affiliation: Natural Health & Food Products Research Group, British Columbia Institute of Technology, 3700 Willingdon Avenue, Burnaby, BC, V5G 3H2, Canada. paula_brown@bcit.ca.
authors.forename: Paula N
authors.initials: PN
authors.lastname: Brown
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D019587:Dietary Supplements / Q000032:analysis; D044947:Flavonolignans / Q000032:analysis*; D057230:Limit of Detection; D020944:Silybum marianum / Q000737:chemistry*; D012639:Seeds / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D044947:Flavonolignans
keywords: Dietary supplements; Flavonolignans; High-performance liquid chromatography; Silybum marianum (L.) Gaertn; Silymarins; Validation