QUANTITATIVE CHROMATOGRAPHIC METHOD FOR THE DETERMINATION OF LOW-LEVELS OF NITRILOTRIACETIC AND ETHYLENEDIAMINETETRAACETIC ACIDS IN DIETHYLENETRIAMINEPENTAACETIC ACID

A quantitative method for determination of low levels (0.05% w/w) of nitrilotriacetic and ethylenediaminetetraacetic acids in diethylenetriaminepentaacetic acid is described. Palmitic acid is added to the chelator as an internal standard before esterification with methanol containing 2% (v/v) H2SO4. The methyl esters of palmitic, nitrilotriacetic, and ethylenediaminetetraacetic acids are first separated from diethylenetriaminepentaacetate by silicic acid column chromatography and are subsequently quantitated by gas-liquid chromatography. The method is both accurate and reproducible with less than 10% relative error. Thin-layer chromatographic separations of the methyl esters, and quantitation at the 1% level, are also described. © 1979.