PROTON NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPIC DETECTION AND DETERMINATION OF ETHYLENE-GLYCOL DIMETHACRYLATE AS A CONTAMINANT OF METHYL-METHACRYLATE RAW-MATERIAL

A simple, specific, and accurate proton nuclear magnetic resonance (H- 1 NMR) spectroscopic method is presented for detection and assay of et hylene glycol dimethacrylate dimer as a contaminant of methyl methacry late monomer. In addition to minimizing exposure of the analyst to the irritant and toxic methacrylic acid esters, the proposed method requi res no sample preparation. Quantitations are based on integrals for si gnals of methylene protons of ethylene glycol dimethacrylate at 4.37 p pm and methyl protons of methyl methacrylate at 3.70 ppm. Analysis of 10 synthetic mixtures of the monomer with 1-11% of dimer yielded a dim er recovery of 100.5 +/- 2.05% (mean +/- standard deviation). Correspo ndence (correlation coefficient, r = 0.9999) between the amount of dim er added and the amount found was excellent. The proposed method measu res as little as 1% of dimer.