- Determination of the GABA analogue succinic semialdehyde in urine and cerebrospinal fluid by dinitrophenylhydrazine derivatization and liquid chromatography-tandem mass spectrometry: application to SSADH deficiency. Struys, E.A., Jansen, E.E., Gibson, K.M., Jakobs, C. J. Inherit. Metab. Dis. (2005)