Attomole catechins determination by capillary liquid chromatography with electrochemical detection.
Attomole quantities of catechins were determined by a capillary liquid chromatography system with electrochemical detection (CLC-ECD) and the system is applied to the determination of catechins in human plasma. The eight catechins: catechin (C), epicatechin (EC), gallocatechin (GC), epigallocatechin (EGC), catechin gallate (Cg), epicatechin gallate (ECg), gallocatechin gallate (GCg), and epigallocatechin gallate (EGCg), were separated within 10 min using a capillary column (0.2 mm i.d.) and a mobile phase of phosphoric acid (85%)-methanol-water (0.5:27.5:72.5, v/v/v), and were detected at +0.85 V vs. Ag/AgCl. Peak heights were found to be linearly related to the amount of catechins injected, from 200 amol to 500 fmol (r > 0.998). The detection limits of the catechins were 61 amol for EGC, 75 amol for EC, 54 amol for GC, 61 amol for C, 67 amol for GCg, 75 amol for EGCg, 75 amol for ECg and 89 amol for Cg (S/N = 3). Because the present method is highly sensitive and allows facile pretreatment for plasma sample, the time courses of concentrations of catechins (GCg, EC, EGCg, ECg, and Cg) and their conjugates in human plasma obtained from a 10 microl plasma sample after ingestion of green tea could be determined.
Kotani
Akira
A
School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, Japan.
Takahashi
Kouji
K
Hakamata
Hideki
H
Kojima
Satoshi
S
Kusu
Fumiyo
F
D002392:Catechin / Q000031:analogs & derivatives / Q000097:blood*; D002853:Chromatography, Liquid / Q000379:methods*; D004563:Electrochemistry / Q000379:methods; D006801:Humans; D000432:Methanol / Q000737:chemistry; D010756:Phosphoric Acids / Q000737:chemistry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013662:Tea / Q000737:chemistry* / Q000378:metabolism; D013997:Time Factors; D014867:Water / Q000737:chemistry
D010756:Phosphoric Acids; D013662:Tea; D014867:Water; C417940:gallocatechin gallate; C417939:catechin gallate; D002392:Catechin; C062669:epicatechin gallate; C045651:epigallocatechin gallate; C030242:phosphoric acid; C057580:gallocatechol; D000432:Methanol