Isocratic HPLC assay with electrochemical detection of free γ-aminobutyric acid in cerebrospinal fluid

Abstract

A method for measuring γ-aminobutyric acid (GABA) in human cerebrospinal fluid (CSF) by isocratic HPLC with electrochemical detection is described. The method is based on precolumn derivatization of GABA with o-phthaldialdehyde (OPA) and fert-butylthiol (t-BT), separation of the GABA-OPA complex on a reversed-phase column, and quantitation by means of a Coulochem electrochemical detector. The method is highly sensitive and specific for GABA. In three samples of human CSF containing low, medium, and high amounts of GABA, the coefficients of variation between and within runs were 4.5% and 3.6%, respectively. The concentration of GABA in 10 neurologically intact subjects was 92.5 ± 9.4 nmol/L of CSF.