In-situ separation of the matrix for the direct determination of traces ofchromium, cobalt, and nickel in titanium dioxide powder by electrothermal atomic-absorption spectrometry with slurry sampling

A novel method has been developed for the direct determination of traces of chromium, cobalt, and nickel in TiO2 powder; it entails slurry sampling an d electrothermal atomic-absorption spectrometry (ETAAS) with a polytetraflu oroethylene (PTFE) slurry (6% m/v) as fluorinating reagent. The factors whi ch could affect the vaporization of the matrix and analytes were studied in detail; the fluorinating vaporization behavior of the analyte both in the slurry and in solution were also investigated. Owing to the in-situ separat ion of the matrix, the matrix influences were reduced significantly. The pr oposed method has been applied to the direct determination of traces of chr omium, cobalt, and nickel in high-purity TiO2 powder without chemical pretr eatment. Under the optimum experimental conditions the detection limits of the analytes (Cr, Co, and Ni) were 1.9 ng g(-1), 2.4 ng g(-1) and 5.4 ng g( -1), respectively, the relative standard deviations (RSD) were 3.4% (n=6, c =7.0 ng mL(-1)), 2.9% (n=6, c=0.70 ng mL(-1)), and 7.6% (n=6, c=4.0 ng mL(- 1)), again respectively, and the characteristic masses for Cr, Co, and Ni w ere 8.4 pg/0.0044A, 9.3 pg/0.0044A, and 40.0 pg/0.0044A, respectively.