a b s t r a c t: A simple, ultra sensitive and selective method for the spectrophotometric determination of Ir3+ in various synthetic and environmental samples was reported. The analyte ions were collected on a membrane filter in the form of their red complex with 5-(2-benzothiazolyl-azo)8-hydroxy-quinoline (BTAHQ), and the absorption spectra of the colored membrane filters were acquired. Effe…