Quantitative Organic Acids in Urine by Two-Dimensional Gas Chromatography-Time-of-Flight Mass Spectrometry (GCxGC-TOFMS)

Erland Arning, Paula Ashcraft, Jeanna Bennett-Firmin, Lawrence Sweetman

Research output: Contribution to journalArticlepeer-review

Abstract

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 and then derivatized to form pentafluorobenzyl oximes (PFBO) of oxo-acids. 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)
Pages (from-to)351-363
Number of pages13
JournalMethods in molecular biology (Clifton, N.J.)
Volume2546
DOIs
StatePublished - 2022

Keywords

  • Time-of-flight mass spectrometry
  • Trimethylsilyl derivatives
  • Two-dimensional gas chromatography
  • Urine organic acids

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics

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