Determination of Trace Cobalt in Water by Microwave Digestion-Catalytic Fading Spectrophotometry

Abstract

A simple and sensitive catalytic fading spectrophometry was developted for determination the trace cobalt in water treated by microwave digestion. The method is based on catalysis of cobalt on the oxidation of acid chrome blue K by potassium periodate with polyethylene glycol-200 as an activator in boric acid-sodium borate buffer solution. Major factors such as microwave digestion conditions, kinds and dosages of media, reagents and activators, the reaction temperature, the reaction time and coexisting irons were investigated and the optimal experimental conditions are determination wavelength 525 nm, at 80°C reacton for 12 min. The linear range and the detection limit of the method are determinated.The maximum relative standard deviation is 5.68 %, and the recoveries are 96.4 % to 105.9 %. The maximum relative error compared with GB( national standard of china 3838-2002) is below 5.52 %.