Quantitative organic acids in urine by two dimensional gas chromatography-time of flight mass spectrometry (GCxGC-TOFMS)

Lawrence Sweetman, Paula Ashcraft, Jeanna Bennett-Firmin

Research output: Chapter in Book/Report/Conference proceedingChapter

9 Scopus citations


Seventy-six organic acids in urine specimens are determined with quantitative two dimensional Gas Chromatography-Time of Flight Mass Spectrometry (GCxGC-TOFMS). The specimen is treated with urease to remove urea then derivatized to form pentafluorobenzyl oximes (PFBO) of oxoacids. The sample is then treated with ethyl alcohol to precipitate proteins and centrifuged. After drying the supernatant, the organic acids are derivatized to form volatile trimethylsilyl (TMS) derivatives for separation by capillary two dimensional Gas Chromatography (GCxGC) with temperature programming and modulation. Detection is by Time of Flight Mass Spectrometry (TOFMS) with identification of the organic acids by their mass spectra. Organic acids are quantitated by peak areas of reconstructed ion chromatograms with internal standards and calibration curves. Organic acids are quantified to determine abnormal patterns for the diagnosis of more than 100 inherited disorders of organic acid metabolism. Characteristic abnormal metabolites are quantified to monitor dietary and other modes of treatment for patients who are diagnosed with specific organic acid disorders.

Original languageEnglish (US)
Title of host publicationMethods in Molecular Biology
PublisherHumana Press Inc.
Number of pages15
StatePublished - 2016

Publication series

NameMethods in Molecular Biology
ISSN (Print)1064-3745


  • Mass spectrometry
  • Trimethylsilyl derivatives (TMS)
  • Urine organic acid s

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics


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