Summary
The analysis of urinary organic acids is crucial for the diagnosis of many inborn errors of metabolism. A vital part of the analytical process is the extraction procedure. The sensitivity and linearity of the analysis of 26 diagnostically important urinary metabolites with tetrahydrofuran (THF) and ethyl acetate (EtOAc) as extraction solvents were determined by gas chromatography–mass spectrometry. Good linearity (r 2 > 0.90) was observed for all of the compounds in the investigated concentration range (290–900 μmol/L) for both solvents. For less polar compounds, THF extraction yielded lower or similar sensitivities as compared with EtOAc (sensitivity ratio: 0.6–1.3). For more polar compounds, however, much higher sensitivities were observed when THF was used (sensitivity ratio: 1.8–17.2). Our results provide information concerning the use of THF for the sensitive quantitative analysis of polar urinary metabolites which are difficult to quantify using EtOAc.
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Communicating editor: Verena Peters
Competing interests: None declared
References to electronic databases: Glutaric aciduria type I (GA I): OMIM 231670. Glutaric aciduria type II (GA II): OMIM 231680. Methylmalonic aciduria (MMA): OMIM 251000. Propionic aciduria (PA): OMIM 606054.
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Wittmann, G., Karg, E., Mühl, A. et al. Comparison of tetrahydrofuran and ethyl acetate as extraction solvents for urinary organic acid analysis. J Inherit Metab Dis 31, 73–80 (2008). https://doi.org/10.1007/s10545-007-0767-8
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DOI: https://doi.org/10.1007/s10545-007-0767-8