title: Determination of folates by HPLC-chemiluminescence using a ruthenium(II)-cerium(IV) system, and its application to pharmaceutical preparations and supplements.
abstract: A chemiluminescence (CL) reaction of folic acid (FA) with ruthenium (II) and cerium (IV) was applied to quantify FA-related compounds such as FA, dihydrofolic acid, tetrahydrofolic acid, 5-methyltetrahydrofolic acid, 5-formyltetrahydrofolic acid and methotrexate (MTX). Among the FAs, 5-methyltetrahydrofolic acid provided the highest CL intensity. HPLC-CL detection of FA was applied to quantify FA in pharmaceutical preparations and supplements. Analytical samples were separated on a semi-micro ODS column with a mixture of 20 mM phosphate buffer (pH 5.7) and acetonitrile (94 : 6, v/v %). The separated samples were mixed with a post-column CL reagent consisting of 1.5 mM Ru(bipy)3 (2+) and 1.0 mM Ce(SO4)2 , then the generated CL was monitored. The calibration range for FA was 10-100 μM and the limit of detection was 1.34 μM (signal-to-noise ratio of 3). Repeatabilities were 4.2, 4.6 and 5.0 RSD% (10, 25, 50 μM), and the recoveries for FA supplement, vitamin B complex supplement and FA-containing medication (tablet) were 102.4 ± 10.5, 103.3 ± 13.3 and 100.3 ± 8.5%, respectively. The described method is robust against changes in the chromatographic parameters of ± 3.3 or ± 1.5%. The measured FA content corresponded well to the labeled content of FA-containing products (100.6-104.9%), demonstrating the precision and accuracy of this method for the evaluation of FA pharmaceutical preparations.
authors.affiliation: Division of Analytical Research for Pharmacoinformatics, Graduate School of Biomedical Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki, 852-8521, Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Ikeda
authors.forename: Kosuke
authors.initials: K
authors.lastname: Ichiyama
authors.forename: Naoto
authors.initials: N
authors.lastname: Tabuchi
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Wada
authors.forename: Naotaka
authors.initials: N
authors.lastname: Kuroda
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Nakashima
mesh_terms: D002563:Cerium / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D005492:Folic Acid / Q000032:analysis*; D049449:Luminescence; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*
chemical_list: D004364:Pharmaceutical Preparations; D002563:Cerium; D012428:Ruthenium; D005492:Folic Acid
keywords: chemiluminescence; folic acid; pharmaceutical preparation; ruthenium; supplement