title: Development of a simplified method for the determination of folates in baker's yeast by HPLC with ultraviolet and fluorescence detection.
abstract: A simplified HPLC method for rapid determination of folates in yeast with ultraviolet and fluorescence detection without sample purification has been developed. By use of the column Aquasil C(18), specially designed for polar analytes, and gradient elution, it was possible to separate and determine five folate derivatives: tetrahydrofolate, 5-methyltetrahydrofolate, and 5-formyltetrahydrofolate with fluorescence detection, and 10-formylfolic acid and folic acid with ultraviolet detection. The sample preparation required only a small amount of dry yeast (25-50 mg) and included an extraction of folates by heat treatment and deconjugation of folate polyglutamates to monoglutamates with the use of rat serum conjugase. Validation involved investigation of matrix effects, determination of recovery by standard addition method, repeatability, and stability tests. The dominating folate forms in commercial dry baker's yeast were found to be tetrahydrafolate and 5-methyltetrahydrofolate with a total folate content of 2890 microg/100 g (63.4 nmol/g). The simplicity of the method makes it suitable for folate screening studies of different yeast strains.
authors.affiliation: Department of Food Science, Swedish University of Agricultural Sciences, P. O. Box 7051, SE-750 07 Uppsala, Sweden. johan.partring@lmv.slu.se
authors.forename: Johan D M
authors.initials: JD
authors.lastname: Patring
authors.forename: Jelena A
authors.initials: JA
authors.lastname: Jastrebova
authors.forename: Sofia B
authors.initials: SB
authors.lastname: Hjortmo
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Andlid
authors.forename: I Margaretha
authors.initials: IM
authors.lastname: Jägerstad
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005492:Folic Acid / Q000032:analysis*; D015203:Reproducibility of Results; D012441:Saccharomyces cerevisiae / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013763:Tetrahydrofolates / Q000032:analysis
chemical_list: D013763:Tetrahydrofolates; C030371:5,6,7,8-tetrahydrofolic acid; D005492:Folic Acid; C005984:5-methyltetrahydrofolate