False results caused by solvent impurity in tetrahydrofuran for MALDI TOF MS analysis of amines.
Tetrahydrofuran (THF) is one of the most frequently used solvents in the MALDI TOF MS analysis of synthetic compounds. However, it should be used with caution because a trace amount of 4-hydroxybutanal (HBA) might be generated and accumulated in THF during storage. Since only a tiny amount of analytes is required in MALDI MS measurements, a trace amount of HBA might have a significant effect on the MS results. It was found that HBA will quickly react with primary and secondary amino compounds, leading to false results about the sample composition with an extra series of ions with additional mass of 70 Da in between. The formation of HBA can be inhibited by butylated hydroxytoluene (BHT) antioxidant. Therefore, when THF is required as the solvent for sample preparation, it is strongly recommended to use a BHT-stabilized one, at least for the analysis of compounds with amino groups.
Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands, x.w.lou@tue.nl.
Xianwen
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Lou
Christianus M A
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Leenders
Arthur H A M
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van Onzen
Ralf A A
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Bovee
Joost L J
JL
van Dongen
Jef A J M
JA
Vekemans
E W
EW
Meijer