title: A capillary liquid chromatographic/tandem mass spectrometric method for the quantification of gamma-aminobutyric acid in human plasma and cerebrospinal fluid.
abstract: A sensitive and reliable method for the determination of gamma-aminobutyric acid (GABA), a major inhibitory neurotransmitter, in human plasma and cerebrospinal fluid (CSF) has been developed. The method is based on capillary liquid chromatography (LC)/tandem mass spectrometry (MS/MS) using deuterium-labeled GABA (gamma-aminobutyric acid-2,2-D(2), GABA-d(2)) as internal standard. Pre-column derivatization with 7-fluoro-4-nitrobenzoxadiazole (NBD-F) was deployed, allowing both effective in-line pre-concentration and sensitive tandem MS detection of the analyte. An extraction column (10 mm x 0.25 mm, 7 microm, C(18)) was used for preconcentrating and stacking the sample. Separation was carried out on an analytical column (50 mm x 0.25 mm, 5 microm, C(18)). Characteristic precursor-to-product ion transitions, m/z 267--> 249 (for NBD-GABA) and m/z 269--> 251 (for NBD-GABA-d(2)) were monitored for the quantification. A linear calibration curve from 10 to 250 ng/mL GABA with an r(2) value of 0.9994 was obtained. Detection limit was estimated to be 5.00 ng/mL GABA (S/N = 3). Human plasma and CSF samples were analyzed. The concentrations of GABA were found to be 98.6 +/- 33.9 ng/mL (mean +/- S.D., n = 12), and 44.3 +/- 10.0 ng/mL (n = 6) in plasma and CSF, respectively.
authors.affiliation: Department of Chemistry, Jackson State University, 1400 Lynch St., Jackson, MS 39217, USA.
authors.forename: Yaru
authors.initials: Y
authors.lastname: Song
authors.forename: Ming
authors.initials: M
authors.lastname: Shenwu
authors.forename: Dirk M
authors.initials: DM
authors.lastname: Dhossche
authors.forename: Yi-Ming
authors.initials: YM
authors.lastname: Liu
mesh_terms: D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D012015:Reference Standards; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D005680:gamma-Aminobutyric Acid / Q000097:blood* / Q000134:cerebrospinal fluid*
chemical_list: D005680:gamma-Aminobutyric Acid