title: An LC method for monitoring medium-chain fatty acid permeation through CaCo-2 cell monolayers.
abstract: A simple method was developed for monitoring the permeation of medium-chain fatty acids of C8 (octanoic acid) and C10 (decanoic acid) through CaCo-2 cell monolayers by high-performance liquid chromatography with electrochemical detection (HPLC-ECD). The detection was made based on the electrochemical reduction prepeak of quinone caused by acids, requiring the fabrication of a two-channel HPLC-ECD system. In one channel, acetonitrile-water (7:3, v/v) was used as a mobile phase to separate acids by a C30 column. In the other channel, acetonitrile-water (7:3, v/v) containing 6 mmol/L 3,5-di-t-butyl-1,2-benzoquinone and 20 mmol/L LiClO(4) was used as a quinone solution to detect acids by an electrochemical cell with a glassy carbon working electrode. In this HPLC-ECD system, eluted acids were mixed with the quinone solution in a post column fashion to obtain current signals caused by acids. The peak area was found to be linearly related to the acid amount ranging from 25 to 1,000 pmol (r > 0.992). The detection limits of octanoic acid and decanoic acid were 7.5 and 8.8 pmol, respectively. Octanoic acid and decanoic acid spiked into cell culture media samples were extracted with acetonitrile and their recoveries were more than 89.5% with an RSD of less than 8.2%. This method was applied to the permeation experiment of octanoic acid and decanoic acid with CaCo-2 cell monolayers formed on the Transwell system.
authors.affiliation: Department of Analytical Chemistry, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Horinouchi 1432-1, Hachioji, Tokyo, 192-0392, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Hideki
authors.initials: H
authors.lastname: Hakamata
authors.forename: Akira
authors.initials: A
authors.lastname: Yamaguchi
authors.forename: Fumiyo
authors.initials: F
authors.lastname: Kusu
mesh_terms: D016227:Benzoquinones / Q000737:chemistry; D018938:Caco-2 Cells; D002210:Caprylates / Q000032:analysis / Q000493:pharmacokinetics; D002463:Cell Membrane Permeability; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003652:Decanoic Acids / Q000032:analysis / Q000493:pharmacokinetics; D004563:Electrochemistry / Q000379:methods*; D005227:Fatty Acids / Q000032:analysis* / Q000493:pharmacokinetics*; D006801:Humans; D010084:Oxidation-Reduction; D012680:Sensitivity and Specificity
chemical_list: D016227:Benzoquinones; D002210:Caprylates; D003652:Decanoic Acids; D005227:Fatty Acids; C004532:quinone; C031071:decanoic acid; C031492:octanoic acid