2ND-DERIVATIVE FOURIER-TRANSFORM INFRARED-SPECTRA OF SEAWEED GALACTANS

The Fourier transform infrared spectra of agar, agarose, kappa-, iota-, and lambda-carrageenan, and of Chondrus canaliculatus, Iridaea ciliata, I. membranacea, I. laminarioides and Gracilaria chilensis polysaccharides were recorded in the 4000-400 cm-1 region. The bands in the second derivative mode are sharper and more bands are resolved than in the normal spectra. Agar, agarose and G. chilensis phycocolloids exhibit diagnostic bands at almost-equal-to 790 and almost-equal-to 713 cm-1 . kappa-, iota- and lambda-carrageenans, and native carrageenan-type polysaccharides from C. canaliculatus and Iridaea species exhibit bands at around 1160, 1140, 1100, 1070, 1040, 1008, 610, and 580 cm-1. Therefore, FT-IR spectroscopy in the second-derivative mode may be applied to differentiate between agar- and carrageenan-types seaweed galactans.