USE OF FLOW INJECTION INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY FOR THE DETERMINATION OF NIOBIUM, VANADIUM, AND TITANIUM IN MICROALLOYEDSTEELS

The use of microsampling flow injection inductively coupled plasma-mas s spectrometry for the determination of Nh, V, and Ti in microalloyed steels samples is described. A microwave nitric acid digestion procedu re, resulting in 0.4% m/v Fe [approximate to 1.75% m/v (NO3)(3)Fe] tes t solutions, was used for sample dissolution. The flow injection param eters, such as carrier flow rate and sample loop volume, were optimize d with respect to sensitivity and stability. Yttrium, with an ionizati on potential close to that of the analytes considered, and with a clos e mass number, was used as internal standard. The obtained detection l imits, in mu g of analyte per gram of steel, were 0.010 for Nb, 0.017 for Ti, and 0.025 for V. The RSD values, at concentration levels of mo re than 10 times the detection limit, were less than 1.5%. Three certi fied reference materials, from the National Institute of Standards and Technology (Gaithersburg, MD)-NIST 2165, 2166, and 2167-were analyzed , from 0.4% m/v steel sample solutions, with 1% v/v HNO3 multielement calibration solutions. The close agreement with the certified values d emonstrates the accuracy of the method developed.