[Spectrophotometric method of determining aminoglycoside antibiotics].

Azo-derivatives of chromotropic acid and azo-dyes of the stilbene series were studies as possible reagents for photometric determination of aminoglycoside antibiotics (AB) in biological materials. The complex of Pr3+ with stilbazochrome-P (Sch-P) proved to be the best precipitant of AB. P (Sch-P) with Pr3+ and AB in acetate and citrate buffer-solutions formed a precipitate with AB:Pr:Sch-P = 1 : 1 : 3. Most of the metallic cations and anions did not prevent formation of the precipitate in the citrate buffer. A procedure for determination of 0.01--100 micrograms of AB in biological materials was developed with the use of Sch-P. The procedure is based on separation of the AB:Pr:Sch-P precipitate and photometry of the sypernatant solution at 560 nm.