Simultaneous determination of cobalt and nickel in catalyst by microwave digestion-dual wavelength equal absorption spectrophotometry

Catalyst samples are digested in a microwave digestion system. The optimum parameters for microwave digestion are selected. Cobalt and nickel in the mixture of Co2+ and Ni2+ with 4-(2-pyridylazo) resorcinol (PAR) can be determined simultaneously by dual-wavelength equal absorption spectrophotometry. By means of the combination of two methods, Co2+ and Ni2+ in catalyst can be determined rapidly, accurately, and contamination problems avoided. The linear ranges are 0-30 mug(.)25 mL(-1) for Co2+ and 0-25 mug(.)25 mL(-1) for Ni2+. The recoveries of Co2+ and Ni2+ in synthetic samples are between 98.2 % - 103.6 % and between 97.9 % - 103.7 %, respectively. The relative standard deviations of analytical results in catalyst samples are less than 2.2 % for Co2+ and less than 1.8 % for Ni2+, and relative errors are less than +/- 2.5 % for Co2+ and Ni2+