%0 Journal Article %T Hydrolysis and transesterification of parabens in an aqueous solution in the presence of glycerol and boric acid %A Oldrich Farsa %A Jan Subert %A Marie Mare£¿kov¨¢ %J Journal of Excipients and Food Chemicals %D 2011 %I %X In a solution containing 0.067% methylparaben, 0.033% propylparaben, 3.4% glycerol and 2.0% boric acid,concentrations of both parabens, 4-hydroxybenzoic acid and 2,3-dihydroxypropyl 4-hydroxybenzoate weremonitored for up to 68 months storage. 4-hydroxybenzoic acid is the main hydrolysis product of parabens,while 2,3-dihydroxypropyl 4-hydroxybenzoate was proposed as the main product of transesterification of parabens with glycerol. Results of an HPLC evaluation of parabens, 4-hydroxybenzoic acid and 2,3-dihydroxypropyl 4-hydroxybenzoate showed that the decomposition of 68 months old samples stored at room temperature did not exceed 2.0%. The stability of both parabens in a medicinal preparation of the statedcomposition has thus been satisfactorily demonstrated after more than 5 years of storage under ambient conditions. The transesterification reaction was shown to influence the chemical stability of parabens to an extent comparable to hydrolysis. Moreover, the presence of 2,3-dihydroxypropyl 4-hydroxybenzoate in the solution containing glycerol and boric acid was confirmed by 1H-NMR spectroscopy. %K parabens %K glycerol %K boric acid %K transesterification %K hydrolysis %K 2 %K 3-dihydroxypropyl 4 -hydroxy-benzoate %K 1H-NMR %U http://ojs.abo.fi/index.php/jefc/article/view/87/83