Rm. Kok et al., STABLE-ISOTOPE DILUTION ANALYSIS OF GABA IN CSF USING SIMPLE SOLVENT-EXTRACTION AND ELECTRON-CAPTURE NEGATIVE-ION MASS FRAGMENTOGRAPHY, Journal of inherited metabolic disease, 16(3), 1993, pp. 508-512
GABA plays an important role in various neurological and mental disord
ers, in which elevated as well as decreased concentrations of GABA in
CSF may occur (Jaeken et al 1990; Jakobs et al 1993). Most methods for
determining GABA in brain tissue lack the sensitivity and specificity
for measuring the low, free GABA levels in CSF. Three methods have be
en used to quantitate CSF free GABA: ion-exchange or reversed-phase li
quid chromatography with fluorescence detection (Goldsmith et al 1987;
Carchon et al 1991); gas chromatography-mass spectrometry, requiring
laborious column extraction (Huizinga et al 1978); and radioreceptor a
ssay (Enna et al 1977). The last method is non-specific and thus unrel
iable. We have developed a sensitive, selective and accurate stable is
otope dilution GC-MS assay using a simple extraction procedure and ele
ctron-capture negative ionization (ECNI) mass fragmentographic detecti
on. The method was applied to CSF samples of a patient suffering from
succinic semialdehyde dehydrogenase (SSAD) deficiency (McKusick 271980
) before and during Vigabatrin treatment.