LC-MS/MS Determination of Mono-Glutamate Folates and Folic Acid in Beer
A reliable LC-MS/MS method was developed for determination of folates in beer. Clean-up steps and chromatographic conditions were optimized to remove interferences and decrease the matrix effect. The work showed that an immuno-affinity column designed for folic acid (FA) was also suitable for the oxidized forms 10-formylfolic acid (10-HCO-FA) and 7,8-dihydrofolic acid (DHF), obtaining clean extract and improving the limit of detection. For the other vitamer forms, an Oasis MAX column was used. For chromatographic conditions, a RP-18 column with low ligand density showed satisfactory retention times; moreover, the use of methanol instead of acetonitrile lowered the limit of detection up to 0.1 μg l−1. The most popular beers in Italy were collected and analyzed; mainly oxidized mono-glutamate forms, in particular 10-HCO-FA and FA, were found, at levels from 12.4 to 98.6 μg l−1 and 1.4 and 11.9 μg l−1, respectively. The vitamers 5-formyl-tetrahydrofolate and 5-methyl-tetrahydrofolate were also detected.
The present work was supported by the European Foundation for Alcohol Research (ERAB, Project EA 15 42).
Compliance with Ethical Standards
Conflict of Interest
Terenzio Bertuzzi declares that he has no conflict of interest. Silvia Rastelli declares that she has no conflict of interest. Annalisa Mulazzi declares that she has no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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