The estimation of BZ55 and sulphonamides in blood sugar filtrates.

Following reports by Franke and Fuchs (1955) and by Bertram, Bendfeldt, and Otto (1955) that oral administration of the sulphonamide Nisulphanilyl-N2-n-butylcarbamide could successfully control diabetes, considerable interest has centred on this compound. It has been used on a large scale in Germany, with apparently successful results, in a proportion of cases, chiefly elderly non-ketonic diabetics. Clinical trials in Britain, however (Duncan, Baird, and Dunlop, 1956; Walker, Leese, and Nabarro, 1956), have suggested that the limited utility of the compound is outweighed by its potentially toxic properties. A considerable amount of research work is proceeding, and it seems likely that other compounds of related structure will be synthesized and tested for their antidiabetic effect. The present work arose from the observation that Bratton and Marshall's (1939) method for sulphonamide estimation could not be applied to the filtrate used in the modified Schaffer-Hartmann blood sugar method of King, Haslewood, and Delory (1937) and King, Haslewood, Delory, and Beall (1942). Bratton and Marshall's method, carried out on these filtrates, produces a deep blue which effectively masks the purple of the final azo dye. The blue apparently results from the reaction of nitrous acid with free tungstate followed by further reaction with the coupling agent, N(1naphthyl)ethylenediamine dihydrochloride. It was found that this effect could be avoided by using N-sulphatoethyl-m-toluidine as the couplingagent. The latter substance is also more stable, both in solid form and in solution, than N(I-naphthyl)ethylenediamine, and has the further advantage that it does not combine with free nitrous acid, and it is therefore not necessary to add ammonium sulphamate to remove nitrous acid before coupling. The present method permits of simultaneous estimations of sugar and sulphonamides on a 0.2 ml. specimen of capillary blood.