Fremgangsmåde til fremstilling af et diagnostisk præparat

Diagnostic compositions for detecting ketones in body fluids comprise sodium nitroprusside, a pH 8-10 buffer, a water-soluble aminoacid and an organic film-forming polymer impregnated in a bibulous material. The buffer is preferably a disodium/trisodium phosphate buffer but borates, citrates, carbonates and ethylene diamine tetraacetic acid sodium salt buffers are mentioned. The amino-acids specified are glycine and alanine. Specified polymers are polyvinylpyrrolidone-vinyl acetate copolymers, vinylpyrrolidone-styrene copolymers, copolymers and interpolymers of methyl vinyl ether and maleic anhydride, polyethylene glycol, polyvinyl acetate, water-soluble acrylic copolymers, and ethyl cellulose. The impregnation is performed in two stages: first the bibulous stick or strip is impregnated with an aqueous solution of buffer and amino acid and after drying, impregnating with the nitroprusside and polymer in an organic solvent, e.g. methanol, ethanol, dimethyl sulphoxide, ethyl lactate or dimethyl formamide and mixtures thereof. Diluents such as chloroform, carbon tetrachloride and benzene, and wetting agents such as diglycol laurate, organic phosphate esters of anionic detergents in ethanol and "Aerosol" may be added to the second solution.