Determination of gabapentin in serum using solid-phase extraction and gas-liquid chromatography.

A gas-liquid chromatographic method for the determination of gabapentin (Neurontin) is described. The method involves extracting 0.5 mL of acidified sample by C18 solid-phase column, derivatization with MTBSTFA plus 1% tBDMCS, and analysis on an HP-1 column with a flame-ionization detector. Quantitation was performed with peak-height ratios of gabapentin to a gabapentin analogue [(1-aminomethyl-1-cycloheptyl) acetic acid] as the internal standard. The assay had a limit of detection of 0.2 mg/L and a linear range from 0.5 to 30.0 mg/L. Several compounds were analyzed for potential interference, and none interfered with the assay.