title: Determination of trigonelline, nicotinic acid, and caffeine in Yunnan Arabica coffee by microwave-assisted extraction and HPLC with two columns in series.
abstract: A simple, rapid method was developed for simultaneous extraction of trigonelline, nicotinic acid, and caffeine from coffee, and separation by two chromatographic columns in series. The trigonelline, nicotinic acid, and caffeine were extracted with microwave-assisted extraction (MAE). The optimal conditions selected were 3 min, 200 psi, and 120 degrees C. The chromatographic separation was performed with two columns in series, polyaromatic hydrocarbon C18 (250 x 4.6 mm id, 5 microm particle size) and Bondapak NH2 (300 x 3.9 mm id, 5 microm particle size). Isocratic elution was with 0.02 M phosphoric acid-methanol (70 + 30, v/v) mobile phase at a flow rate of 0.8 mL/min. Good recoveries and RSD values were found for all analytes in the matrix. The LOD of the three compounds was 0.02 mg/L, and the LOQ was 0.005% in the matrix. The concentrations of trigonelline, nicotinic acid, and caffeine in instant coffee, roasted coffee, and raw coffee (Yunnan Arabica coffee) were assessed by MAE and hot water extraction; the correlation coefficients between concentrations of the three compounds obtained were close to 1.
authors.affiliation: Supervision and Testing Center for Farm Product Quality, Ministry of Agriculture (Kunming), Institute of Quality Standard and Testing Technology, Yunnan Academy of Agriculture Science, 650223, Kunming, People's Republic of China. cmliu_0@sina.com
authors.forename: Hongcheng
authors.initials: H
authors.lastname: Liu
authors.forename: Jinliang
authors.initials: J
authors.lastname: Shao
authors.forename: Qiwan
authors.initials: Q
authors.lastname: Li
authors.forename: Yangang
authors.initials: Y
authors.lastname: Li
authors.forename: Hong Mei
authors.initials: HM
authors.lastname: Yan
authors.forename: Lizhong
authors.initials: L
authors.lastname: He
mesh_terms: D000470:Alkaloids / Q000032:analysis*; D002110:Caffeine / Q000032:analysis*; D002623:Chemistry Techniques, Analytical / Q000379:methods; D002845:Chromatography / Q000379:methods*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003069:Coffee / Q000378:metabolism*; D005504:Food Analysis / Q000379:methods*; D000432:Methanol / Q000737:chemistry; D008872:Microwaves; D009525:Niacin / Q000032:analysis*; D010756:Phosphoric Acids / Q000737:chemistry; D012044:Regression Analysis; D015203:Reproducibility of Results; D013696:Temperature; D013997:Time Factors; D014867:Water
chemical_list: D000470:Alkaloids; D003069:Coffee; D010756:Phosphoric Acids; D014867:Water; D009525:Niacin; D002110:Caffeine; C009560:trigonelline; C030242:phosphoric acid; D000432:Methanol