title: Quantitation of the hydroxycinnamic acid derivatives and the glycosides of flavonols and flavones by UV absorbance after identification by LC-MS.
abstract: A general approach was developed to quantify hydroxycinnamic acid derivatives and the glycosides of flavonols and flavones using UV molar relative response factors (MRRFs). More than 90 standards were analyzed by LC-MS and divided into five groups based on the λ(max) of their band I absorbance profiles. For each group, a commercially available standard was chosen as the group reference standard. Response factors were determined for each standard in each group as purchased (MRRF) and, when possible, after vacuum drying (MRRF(D)). The MRRF(D) values for 17 compounds whose λ(max) values fell within ±2 nm of the group reference standard were 1.01 ± 0.03. MRRF values for compounds whose λ(max) values fell within ±10 nm of the group reference standard were 0.96 ± 0.13. Group reference standards were used to quantify 44 compounds in Chinese lettuce, red onion, and white tea. This approach allows quantitation of numerous compounds for which there are no standards.
authors.affiliation: Food Composition and Methods Development Laboratory, Beltsville Human Nutrition Research Center, Agricultural Research Service, USDA, Beltsville, Maryland 20705-3000, United States. longze.lin@ars.usda.gov
authors.forename: Long-Ze
authors.initials: LZ
authors.lastname: Lin
authors.forename: James
authors.initials: J
authors.lastname: Harnly
authors.forename: Ren-Wei
authors.initials: RW
authors.lastname: Zhang
authors.forename: Xian-E
authors.initials: XE
authors.lastname: Fan
authors.forename: Hui-Jia
authors.initials: HJ
authors.lastname: Chen
mesh_terms: D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods* / Q000592:standards; D003373:Coumaric Acids / Q000032:analysis* / Q000737:chemistry; D047309:Flavones / Q000032:analysis* / Q000737:chemistry; D044948:Flavonols / Q000032:analysis / Q000737:chemistry; D005504:Food Analysis / Q000379:methods; D006027:Glycosides / Q000032:analysis* / Q000737:chemistry; D018545:Lactuca / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods; D019697:Onions / Q000737:chemistry; D012015:Reference Standards; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*; D013662:Tea / Q000737:chemistry
chemical_list: D003373:Coumaric Acids; D047309:Flavones; D044948:Flavonols; D006027:Glycosides; D013662:Tea