SEPARATION AND QUANTIFICATION OF TETRAETHYLENE GLYCOL MONOHEPTANOATE AND DIHEPTANOATE BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Tetraethylene glycol mono- and diheptanoate were prepared by direct esterification of heptanoic acid with tetraethylene glycol. The constituents of the reaction were separated by thin layer chromatography with flame ionization detection, but only tetraethyleneglycol diheptanoate could be determined by this method. The main constituents of the reaction mixture were quantified by HPLC using two different mobile phases on a non-bonded silica column. Acetonitrile acidified with 0.3% acetic acid was used to separate and quantify the monoester and tetraethylene glycol, while hexane-isopropanol (80:20, v/v) acidified with 0.3% acetic acid was used to separate and quantify heptanoic acid and the diester. The starting compounds and the products of the reaction could be thus separated and quantified accurately using these two eluents without derivatization of the hydroxylated compounds.