2003 Volume 89 Issue 9 Pages 939-942
A sensitive method for the determination of molybdenum in steel has been developed by flow injection-online ion-exchange preconcentration-ICP-AES. Sample is decomposed with a mixed acid by a microwave-assisted digestion. Excess acids are removed by evaporation and the residue is taken up in 0.05 M sulfuric acid and an 50μl aliquot of the sample solution is injected into the flow injection analysis system. Molybdenum in the sample solution is adsorbed on a TEVA resin column and then eluted with 7 M nitric acid. The effluent containing molybdenum is introduced directly into a ultrasonic nebulizer of ICP-AES. The valves and pumps in the flow system are operated automatically by a personal computer. The analytical results obtained for molybdenum at a 0.01 m/m% level in the steel certified reference materials are in good agreement with certified values and the precision (R.S.D.=2.3-2.5%) is satisfactory. The detection limit estimated as 3σ of the background noise is 0.8 ng molybdenum, which corresponds to 8 μg Mo/g when 50 mg of steel sample is analyzed.