Determination of methanol in o,o-dimethyldithiophosphoric acid (DMDTPA) of technical grade by UV/vis spectrophotometry and by HPLC.

摘要: Two procedures are proposed in this work for the determination of methanol impurities o,o-dimethyldithiophosphoric acid (DMDTPA). To avoid possible interferences from main component, DMDTPA was precipitated form insoluble lead complex. Free Pb(II) ions were eliminated with sulfuric and oxidized to formaldehyde potassium permanganate methanesulfonic medium. Finally, excess oxidizing agent neutralized saturated sodium oxalate. The above pretreatment procedure identical spectrophotometric assay chromatographic determination. In first case, solution obtained treated Nash reagent 3,5-diacetyl-1,4-dihydrolutidine (max = 415 nm). calibration range 0.1–1.0% (methanol DMDTPA), analytical figures merit were: R 2 0.9993, quantification limit 0.02% coefficient variance ( n 5) 0.1% 0.4% respectively 6.7% 2.4%. Recoveries sample fortified 0.1, 0.2, (in DMDTPA) 99–105%. For procedure, derivatized 2,4-dinitrophenylhydrazine separation achieved on Luna C18(2) column using isocratic elution acetonitrile–water (70:30, v/v) detection at 360 nm. 0.05–0.25% always higher than 0.999, 0.004% recoveries these same samples 98–101%. No statistically significant differences observed between results analysis technical grade by two (ANOVA,p < 0.05) © 2004 Elsevier B.V. All rights reserved.