Comparative value of chitosan test and enzymatic method for chitin detection

In oorder to check their relative value for the specific identification of chitin on minute pieces of skeletal material, the chitoisan test of Campbell, readapted by Krishan and Sundara-Rajulu and the enzymatic method of Jeuniaux using purified chitinases, were applied simultaneously to the same material. In most cases, both methods gave similar results, the chitosan test being more rapid and useful to locate chitin in composite structures. In two specific cases, these methods yielded contractory results. Fragments of Rhabdopleura sp exoskeleton (Pterobranchia), after alkali treatment, gave a more or less typical colour with chitosan tests, but remained unaltered in pure chitinase solutions without N-acetyl-D-glucosamine production. In the same manner, hooks of Cloesiphon sp (Sipunculida) gave a positive reaction to chitosan test but failed to dissolve in pure chitinase, after repeated incubations at 37°C. It is concluded that, in some cases, undetermined organic substances, which do not correspond to true chitin, may be interpreted as chitin with chitosan test.