Determination of methotrexate in pharmaceutical formulations by flow injection analysis exploiting the reaction with potassium permanganate.
A highly sensitive, precise and accurate flow injection procedure for the determination of methotrexate (MTX) was described. The method was based on oxidation of MTX into highly fluorescence product (2,4-diaminopteridine-6-carboxylic acid) by acidic potassium permanganate. A three-line manifold was used with potassium permanganate as an oxidant (3 mmol l(-1)) and sulfuric acid (6 mmol l(-1)) as carrier streams. The oxidation process was conducted at 65 degrees C through a reaction coil of 3 m (0.5 mm, i.d.). It was essential to eliminate the excess of potassium permanganate before passing to the detector using 8 mmol l(-1) sodium sulfite as a decolorizing stream. The fluorescence intensity was measured at excitation and emission wavelengths of 369 and 465 nm, respectively. The calibration graph was linear over the range 40-400 ng ml(-1) MTX. The developed method was successfully applied to the determination of MTX in pharmaceutical formulations, at a sampling rate of 90 sample h(-1) and showed a % recovery ranging from 99.96 to 100.07 and SD% ranging from 0.51 to 0.65%.
Emara
Samy
S
Department of Analytical Pharmaceutical Chemistry, Faculty of Pharmacy, Suez Canal University, Ismialia 41522, Egypt. samy_emara@hotmail.com
D002138:Calibration; D017022:Flow Injection Analysis / Q000379:methods*; D005453:Fluorescence; D008727:Methotrexate / Q000008:administration & dosage / Q000032:analysis*; D011196:Potassium Permanganate; D013696:Temperature
D011196:Potassium Permanganate; D008727:Methotrexate