title: A validated LC-MS/MS determination method for the illegal food additive rhodamine B: Applications of a pharmacokinetic study in rats.
abstract: Rhodamine B is an illegal and potentially carcinogenic food dye. The aim of this study was to develop a convenient, rapid, and sensitive UHPLC-MS/MS method for pharmacokinetic studies in rats. Rat plasma samples were deproteinized with acetonitrile and separated by UHPLC on a reverse-phase C18e column (100mm×2.1mm, 2μm) using a mobile phase consisting of methanol-5mM ammonium acetate (90:10, v/v). Detection was performed using a triple quadrupole tandem mass spectrometer in the selected reaction monitoring mode at [M](+) ion m/z 443.39→399.28 for rhodamine B and [M+H](+) ion m/z 253.17→238.02 for 5-methoxyflavone as the internal standard. This method was specific and produced linear results over a concentration range of 0.5-100ng/mL, with a lower limit of quantitation of 0.5ng/mL. All validation parameters, including the inter-day, intra-day, matrix effect, recovery, and stability in rat plasma, were acceptable according to the biological method validation guidelines developed by the FDA (2001). This method was successfully applied to a pharmacokinetic study in rats; oral administration of 1mg/kg of rhodamine B yielded a time to maximum concentration (Tmax) of 1.3±0.4h and an elimination half-life of 8.8±1.4h, with a clearance of 229.7±19.4mL/h/kg. These pharmacokinetic results provide a constructive contribution to our understanding of the absorption mechanism of rhodamine B and support additional food safety evaluations.
authors.affiliation: Institute of Traditional Medicine, National Yang-Ming University, Taipei 112, Taiwan.
authors.forename: Yung-Yi
authors.initials: YY
authors.lastname: Cheng
authors.affiliation: Institute of Traditional Medicine, National Yang-Ming University, Taipei 112, Taiwan; Graduate Institute of Acupuncture Science, China Medical University, Taichung 404, Taiwan; School of Pharmacy, College of Pharmacy, Kaohsiung Medical University, Kaohsiung 807, Taiwan; Department of Education and Research, Taipei City Hospital, Taipei 103, Taiwan. Electronic address: thtsai@ym.edu.tw.
authors.forename: Tung-Hu
authors.initials: TH
authors.lastname: Tsai
mesh_terms: D000818:Animals; D019540:Area Under Curve; D002853:Chromatography, Liquid / Q000379:methods*; D051381:Rats; D015203:Reproducibility of Results; D012235:Rhodamines / Q000493:pharmacokinetics*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D012235:Rhodamines; C029773:rhodamine B
keywords: Food safety; Illegal food additive; Pharmacokinetics; Rat plasma; Rhodamine B; UHPLC-MS/MS