title: Specific and sensitive quantification of folate vitamers in foods by stable isotope dilution assays using high-performance liquid chromatography-tandem mass spectrometry.
abstract: Stable isotope dilution assays were developed for the quantification of the folate vitamers 5-methyltetrahydrofolate, 5-formyltetrahydrofolate, tetrahydrofolate, 10-formylfolate and pteroylglutamic acid in food samples by using deuterated isotopomers as internal standards. Vitamers and their labeled analogues were analyzed simultaneously by HPLC/MS/MS using selected reaction monitoring, which allowed a higher specificity than other methods published previously. Sample preparation involved treatment by protease in sequence with alpha-amylase and rat serum deconjugase, followed by anion exchange chromatography. The detection limits for 5-methyltetrahydrofolate, 5-formyltetrahydrofolate, tetrahydrofolate, 10-formylfolate and pteroylglutamic acid were found to be 0.5, 1.2, 1.5, 0.6 and 2.6 microg/100 g fresh weight, respectively. Using the new method, folate contents were determined in meat, cereals, and vegetables. Data were in good agreement with literature data, except results for broccoli, which were much lower than reported in previous studies.
authors.affiliation: Institut für Lebensmittelchemie, Technischen Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany.
authors.forename: Achim
authors.initials: A
authors.lastname: Freisleben
authors.forename: Peter
authors.initials: P
authors.lastname: Schieberle
authors.forename: Michael
authors.initials: M
authors.lastname: Rychlik
mesh_terms: D000818:Animals; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002523:Edible Grain / Q000737:chemistry; D005492:Folic Acid / Q000031:analogs & derivatives* / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D005504:Food Analysis / Q000379:methods*; D007554:Isotopes / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods*; D008460:Meat; D015394:Molecular Structure; D051381:Rats; D012680:Sensitivity and Specificity; D014675:Vegetables / Q000737:chemistry
chemical_list: D007554:Isotopes; D005492:Folic Acid