γ-Radiation produced supported metal complex catalysts V. Determination of rhodium by atomic absorption spectroscopy

Rhodium in polymer-supported catalysts as well as in organorhodium complexes can be determined conveniently by atomic absorption spectroscopy. Following oxidative destruction of the organic material in a mixture of concentrated sulphuric acid and hydrogen peroxide, an aqueous solution to which 2% lanthanum nitrate has been added is aspirated into an air/acetylene flame. A linear calibration graph is obtained at 343.5 nm for rhodium concentrations in the range 0–20 ppm. Standards are prepared by oxidising RhH(CO)(PPh₃)₃] in the same way as the sample. In this way interference by chloride is avoided. This interference is important when large amounts of chloride are present as in commercial rhodium trichloride in aqueous hydrochloric acid solution standards.