Quantitative determination of trimethylamine in urine by solid-phase microextraction and gas chromatography-mass spectrometry.

Trimethylaminuria (fish odour syndrome) is diagnosed from an increase in urinary excretion of trimethylamine with decreased trimethylamine oxide. We report a new quantitative stable isotope dilution gas chromatography-mass spectrometry procedure for the analysis of these metabolites using solid-phase microextraction (SPME). Both polydimethylsiloxane and mixed Carboxen-polydimethylsiloxane SPME fibres were found to be suitable for the headspace extraction of TMA. This new sampling technique could have wide application for the analysis of volatile and semi-volatile compounds by metabolic screening laboratories.