Automated microanalysis of gabapentin in human serum by high-performance liquid chromatography with fluorometric detection

An automated high-performance liquid chromatographic method for the determi nation of gabapentin, 1-(aminomethyl)cyclohexaneacetic acid, in serum is de scribed. The procedure involves protein precipitation with methanol followe d by using a robotized derivatization with o-phthaldialdehyde reagent and a utomated high-performance liquid chromatography. The analog of gabapentin, 1-(aminomethyl)cycloheptaneacetic acid, was used as the internal standard. Blank serum was fortified with gabapentin (0.1-10.0 mu g/ml) and internal s tandard. Separation was achieved on a Waters 5-mu m reversed-phase column ( 10 cm X 4.6 mm) with mobile phase consisting of 0.02 M phosphate buffer (pH 4.5)-acetonitrile (50:50, v/v). Eluents were monitored by fluorescence spe ctroscopy with excitation and emission wavelengths of 230 and 420 nm, respe ctively. The calibration curve for gabapentin in serum was linear (r = 0.99 9) over the concentration range 0.1-10.0 mu g/ml. The inter- and intraassay variations for three different gabapentin concentrations were less than or equal to 10% throughout. The lower limit of quantitation was found to be 0 .1 mu g/ml. Chromatography was unaffected by a range of commonly employed a ntiepileptic drugs or selected amino acids. (C) 1999 Elsevier Science B.V. All rights reserved.