Screening for fatty acid beta oxidation disorders. Acylglycine analysis by electron impact ionization gas chromatography-mass spectrometry.

Urinary acylglycine analysis by chemical ionization (CI) GC-MS has been utilized for more than a decade to screen of fatty acid oxidation disorders. We have developed an alternative GC-MS method involving tert.-butyldimethylsilyl derivatization and standard electron impact ionization. Using six stable isotope labeled internal standards, this method allows the biochemical diagnosis of glutaric aciduria type II and medium chain acyl-CoA dehydrogenase deficiency, and could contribute to the diagnosis of other FAO disorders when used in combination with other biochemical investigations on blood and urine. This method can be conveniently applied to GC-MS system routinely used for organic acid analysis.