Gas chromatography–mass spectrometry with tert.-butyldimethylsilyl derivatization: use of the simplified sample preparations and the automated data system to screen for organic acidemias

A simplified, sensitive screening method for organic acidemias by gas chromatography–mass spectrometry using urease/direct preparations and tert.-butyldimethylsilylation (TBDMS) instead of trimethylsilylation (TMS) is described. We compiled GC–MS data on TBDMS derivatives, including methylene unit values, and quantifying and confirming ions, for use in the automated data system we developed. Quantification using [M-57]+ ions by mass chromatography was more sensitive, and the coefficient variation was smaller, compared with TMS derivatives. We confirmed the usefulness of this system, analyzing urine specimens from 53 patients with 15 different disorders.