title: Purity determination and uncertainty evaluation of folic acid by mass balance method.
abstract: Folic acid is one of the most important nutrient substances for human beings, especially for the pregnant women and infants. Therefore the purity determination of folic acid is particularly important. The mass balance method was employed to determine the purity of folic acid, by using the measures of high performance liquid chromatography (HPLC), Karl Fischer titration and other conventional approach. The moisture quantification of folic acid was a major problem since it is a thermally unstable substance and it is apt to contain crystal water. Therefore, a novel improved Karl Fischer method was established for accurate determination of the water content in folic acid, whose repeatability (RSD=2.9%) was significantly better than that of the original direct injection method (RSD=12%). The purity of folic acid certified reference material (CRM) determined by mass balance method was 90.9% with an expanded uncertainty of 0.35%, and the content of water (the major impurity) was 8.5%, with an expanded uncertainty of 0.32%.
authors.affiliation: College of Science, Beijing University of Chemical Technology, Beijing 100029, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Gong
authors.forename: Ting
authors.initials: T
authors.lastname: Huang
authors.forename: Yi
authors.initials: Y
authors.lastname: Yang
authors.forename: Haifeng
authors.initials: H
authors.lastname: Wang
mesh_terms: D002851:Chromatography, High Pressure Liquid; D005492:Folic Acid / Q000737:chemistry / Q000302:isolation & purification*; D013818:Thermogravimetry; D035501:Uncertainty
chemical_list: D005492:Folic Acid