title: Determination of proanthocyanidins in grape products by liquid chromatography/mass spectrometric detection under low collision energy.
abstract: A method has been established for the identification of proanthocyanidins and quantification of individual monoproanthocyanidins using liquid chromatography/electrospray ionization-mass spectrometric detection (LC/ESI-MSD) for raw grape products. The separated monoproanthocyanidins and oligoproanthocyanidins were individually analyzed and identified by their molecular ion peaks using LC/MS. Using HPLC/ESI-MSD, the proanthocyanidin monomers, (+)-catechin (C), (-)-epicatechin (EC), (-)-catechin gallate (CG), and (-)-epicatechin gallate (ECG) in grape products were successfully quantified by LC/MS/MS detection of protonated molecular ions and characteristic fragment ions for each component under the optimized low collision energy level of 20%. For the investigated concentration ranges of C (21.88-11,200 ng/mL), EC (21.10-10,800 ng/mL), CG (36.72-18,800 ng/mL), and ECG (39.84-20,400 ng/mL), good linearities (r2 > 0.99) for standard curves were obtained. Validation of this method showed an accuracy that was well below 15% and precision (RSD) within 8% for the four compounds. The method proposed here is simple, sensitive, and allows a direct sample preparation procedure. This is the first method that enables the determination of individual monoproanthocyanidins in grape products without any solid-phase extraction.
authors.affiliation: New Use Agriculture and Natural Plant Products Program, Department of Plant Biology and Pathology, Cook College, Rutgers University, New Brunswick, New Jersey 08901-8520, USA. qlwu@aesop.rutgers.edu
authors.forename: Qingli
authors.initials: Q
authors.lastname: Wu
authors.forename: Mingfu
authors.initials: M
authors.lastname: Wang
authors.forename: James E
authors.initials: JE
authors.lastname: Simon
mesh_terms: D000872:Anthocyanins / Q000032:analysis* / Q000737:chemistry; D002853:Chromatography, Liquid / Q000379:methods; D013058:Mass Spectrometry / Q000379:methods; D044945:Proanthocyanidins; D027843:Vitis / Q000737:chemistry*
chemical_list: D000872:Anthocyanins; D044945:Proanthocyanidins; C013221:proanthocyanidin