The determination of the di-and mononitrates of ethylene glycol and 1,2-propylene glycol in blood by colorimetric and gas-chromatographic methods

Abstract

Methods are described for the determination of the nitrate esters, ethylene glycol dinitrate, propylene glycol 1,2-dinitrate, ethylene glycol mononitrate, propylene glycol 1-mononitrate and propylene glycol 2-mononitrate, in blood. These esters can be removed efficiently from blood by extraction with diethyl ether, and determination of the dinitrates can be carried out colorimetrically, after alkaline hydrolysis, by a diazotisation and coupling reaction. As the mononitrates are not determined by this procedure, they do not interfere with the determination of the corresponding dinitrate. Gas chromatography, with the electron-capture detector, provides a sensitive method for detecting and measuring the mononitrates, with adequate separation from the parent dinitrate, and the latter can also be determined by this method as an alternative to the colorimetric procedure. For both methods the effect of possible interferences is investigated, and the efficiency of recovery from blood over the range 0 to 25 µg of ester is reported.