Analysis and purification of 2-hydroxyethyl methacrylate by means of thin-layer chromatography

Poly(2-hydroxyethyl methacrylate) is nowadays accepted as a biocompatible, safe and stable hydrogel for medical use. In this paper, the use of thin-layer chromatography for the analysis and small-scale preparation of the initial monomer, 2-hydroxyethyl methacrylate, is described. Development on silica gel, with n-hexane-diethyl ether (1:1, v/v) and/or n-hexane-isobutyl methyl ketone-n-octanol (9:2:1, v/v; saturated with 25% nitric acid) is recommended for qualitative analysis. Preparative-scale work is preferably carried out on sulphuric acid-impregnated silica gel, with n-hexane-diethyl ether (1:1, v/v) as mobile phase. Inhibitors are detected by thin-layer chromatography and a drop-test procedure with diazotised sulphanilic acid. The nature of the contaminants present in several commercial samples of 2-hydroxyethyl methacrylate is discussed. n20D values are reported for the system 2-hydroxyethyl methacrylate-water.