Emara S.Masujima T.Zarad W.Kamal M.El-Bagary R.Pharmaceutical Chemistry DepartmentFaculty of PharmacyMisr International UniversityKm 28 Ismailia RoadCairoEgypt; Analytical Molecular Medicine and Devices LaboratoryHiroshima UniversityGraduate School of Biomedical Sciences1-2-3KasumiMinami-kuHiroshima 734-8551Japan; Pharmaceutical Analytical Chemistry DepartmentFaculty of PharmacyModern Sciences and Arts University26 July Mehwar Road intersection with Wahat Road6 October CityEgypt; Pharmaceutical Chemistry DepartmentFaculty of PharmacyCairo UniversityKasr El Aini St.Cairo 11562Egypt2020-01-092020-01-09201320951779https://doi.org/10.1016/j.jpha.2012.10.003PubMed ID :https://t.ly/7OGybScopusA new simple, sensitive and precise green analytical procedure using an automated packed-reactor derivatization technique coupled with on-line solid-phase enrichment (SPEn) has been developed and evaluated to determine trace levels of methotrexate (MTX). The method was based on injection of MTX into a flowing stream of phosphate buffer (0.04 M, pH 3.4), carried through the packed oxidant reactor of Cerium (IV) trihydroxyhydroperoxide for oxidative cleavage of the drug into highly fluorescent product, 2,4-diaminopteridine-6- carboxylic acid, followed by SPEn on a head of short ODS column (10 mm�4.6 mm i.d., 5 ?m particle size). The flow rate was 0.25 mL/min and packed reactor temperature was 40 �C. The trapped product was back-flush eluted from the ODS column to the detector by column-switching with an environmentally friendly mobile phase consisting of ethanol and phosphate buffer (0.04 M, pH 3.4) in the ratio of 5:95 (v/v). The eluent was monitored at emission and excitation wavelengths of 460 and 360 nm, respectively. The calibration curve was linear over the concentration range of 1.25-50 ng/mL with a detection limit of 0.08 ng/mL. The method was successfully applied to determine MTX in pharmaceutical formulations with mean percentage recovery ranging from 99.48 to 99.60. � 2013 Xi'an Jiaotong University.EnglishCerium (IV) trihydroxyhydroperoxideFlow injection analysisFluorescence detectionMethotrexateOn-line solid-phase enrichmentbuffercarboxylic acid derivativeceriumhydroperoxide derivativemethotrexatephosphatearticleconcentration (parameters)derivatizationdrug determinationelutionflow ratefluorescence analysislimit of detectionoxidationparticle sizepHsolid phase extractionArticlehttps://doi.org/10.1016/j.jpha.2012.10.003PubMed ID :