| 5 | On-line coupling of derivatization with pre-concentration to determine trace levels of methotrexate显示文摘A 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 mm particle size). The flow rate was 0.25 mL/min and packed reactor temperature was 40 1C. 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. | Samy Emara Tsutomu Masujima Walaa Zarad Maha Kamal Ramzia EL-Bagary | 2013 | Journal of Pharmaceutical Analysis2013，3，1： | 0 |
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