Spectrophotometric determination of low levels of mono-, di- and triethylene glycols in surface waters

Abstract

A method is proposed for the determination of mono-, di- and triethylene glycols in surface waters, based on the oxidation of the glycols to aldehydes. These are made to react with 3-methylbenzothiazol-2-one hydrazone hydrochloride to give green cationic chromogens, which are then measured spectrophotometrically at 630 nm. Sample blank values, to compensate for natural interferences, are obtained by omitting the oxidation stage. The method enables glycol levels of upwards of 0·5 mg l^–1 to be determined, satisfactory recoveries of each glycol being obtained for concentrations of 1 to 5 mg l^–1, with a precision of 7 per cent., for a range of water samples. A sensitive variation of the method, for the determination of monoethylene glycol alone, is described separately.