Study of the system Os(IV)-chloride-brilliant green: Extraction-spectrophotometric determination of osmium

A sensitive extraction-spectrophotometric method of the determination of osmium, taking advantage of the ion-associate of the chloride osmium anion with brilliant green has been developed. The complex is extracted from aqueous phase with a mixture of C₆H₅Cl + CCl₄ (3 + 1). Molar absorptivity () at 640 nm is 1.95 × 10⁵ liters mol⁻¹cm⁻¹ (specific ABSORPTIVITY = 1.03). The relative standard deviation is 1–3%. The mole ratio of Os:BG in the complex is 1:3. Platinum metals interfere with the determination of osmium. The determination can be highly selective after preliminary separation of osmium by distillation as OsO₄.