Identification of 4,6-O-(1-carboxyethylidene)-D-galactose by combined gas chromatography mass spectrometry

Combined gas chromatography mass spectrometry was used to separate and identify a carrageenan component suspected of being the acid ketal 4,6-O-(1-carboxyethylidene)-D-galactose. The mass spectral fragmentation pattern is presented as evidence of the presence of this component in the carrageenan from Petrocelis middendorfii (P. franciscana).