Determination of titanium by slurry sampling graphite furnace atomic absorption spectrometry with the use of fluoride modifiers

Abstract

A method for the determination of titanium in graphite furnace atomic absorption spectrometry with slurry sampling was developed. Titanium forms thermally stable carbides in the graphite tube that leads to decreased sensitivity and severe memory effects. Various fluorinating agents, BaF(2), NH(4)F, and CHF(3) (Freon-23) were therefore examined in order to reduce or eliminate these problems. Ti was determined, at various concentration levels, in certified reference materials (CRMs) using ultrasonic slurry sampling graphite furnace atomic absorption spectrometry (USS-GFAAS). The three CRMs, GBW 07601 (Human Hair Powder), GBW 07602 (Bush Branches and Leaves), and GBW 07411 (Chinese Soil), contained 2.7 microg g(-1), 95 microg g(-1), and 0.41% Ti, respectively. For comparison, determinations of Ti were made with modifiers (BaF(2) and NH(4)F) and without modifier, using 5% CHF(3) (in argon) for cleaning the graphite furnace. Good accuracy was obtained using aqueous Ti standards for calibration. A homogeneity study showed that Ti was evenly distributed in all the samples at the mg-microg level. The relative standard deviations (RSDs) obtained for the three CRMs were 16%, 11%, and 8% ( n=30). In spite of the wide range of Ti concentrations in the present samples, the same wavelength (365.4 nm) could be used for analysis by varying the slurry sample concentration. The precision was best for the material with the highest titanium content in spite of the fact that only 3 microg of sample was introduced into the furnace.

Determination of Titanium Dioxide Content in Bauxites Using X-ray Fluorescence Spectrometry by Fusion and by Pressing

“…The following tables ( Table 9 and Table 10) show results for "Grčka" bauxite sample obtained by measuring the beads prepared by pressing. Another F-test was conducted in order to test the pre cision of the XRF method for the beads prepared by pressing and the results were as follows: (8) Again, the calculated value was considerably higher than the critical value, the difference between the variances of the two methods was significant and, with the risk of 5%, the zero hypothesis on equality of the variances had to be rejected. The variance of the standard method was higher than the variance of the XRF method, which again leads to the conclusion that the latter is more precise.…”

“…TiO 2 exists in the form such as anatase, rutile and brookite minerals. 5 Various methods have been used for determining titanium content in different types of samples, such as: inductively coupled plasma-atomic emission spectrometry (ICP-AES), 6 inductively coupled plasma-mass spectrometry (ICP-MS), 7 graphite furnace atomic absorption spec-trometry (GFAAS), 8 catalytic adsorptive stripping voltammetry (CASV), 9 neutron activation analysis (NAA), 10 spectrophotometry, 11,12,13 X-ray fluorescence (XRF), 14 and laser induced breakdown spectroscopy (LIBS). 15 Chemical composition of bauxite is usually expressed in the content of Al 2 O 3 , SiO 2 , Fe 2 O 3 , TiO 2 , and CaO, with the loss on ignition at 1075 °C.…”