Contemporary clinical usage of LC/MS: Analysis of biologically important carboxylic acids

Objectives: This review summarizes the current role of LC/MS in the diagnosis and screening of clinical conditions involving the analysis of biologically important carboxylic acids. Design and methods: Carboxylic acids are divided into six logical categories of acid size and function. Details of chromatographic separation methods and modes of mass spectrometer operation are described for each category. Results: The use of LC/MS in clinical applications such as the diagnosis of inherited and acquired metabolic disorders, gastrointestinal disorders, cancer and diabetes and therapeutic drug monitoring is discussed. Conclusions: The mild conditions, speed and sensitivity advantages of LC/MS analysis, over alternatives, are highlighted. The sensitivity and specificity afforded by the combination of tertiary and quaternary ammonium derivatives and tandem mass spectrometry for the analysis of carboxylic acids is emphasized. Potential for a greater range of LC/MS carboxylic analyses, including stereoisomeric intermediates, is predicted.