Recebido em 25/11/11; aceito em 30/1/12; publicado na web em 15/6/12 Hydrogels have been prepared by free-radical solution copolymerization of acrylamide and sodium acrylate (NaAc), with molar ratio ranging from 25/75 to 80/20, respectively, using methylene bisacrylamide as the crosslinking agent. A FTIR spectroscopy procedure to determine the acrylate/acrylamide ratio in these hydrogels was proposed based on absorbance at 1410 cm -1 (nCOO -) and 2940 cm -1 (nCH and nCH 2 ). A straight line with a good linear correlation coefficient (0.998) was obtained by plotting the acrylate content (Ac%) versus relative absorbance (A rel = A 1410 /A 2940 ). Results were confirmed by the amount of sodium cation released in acid medium determined by atomic absorption spectrometry.

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