[Study on the adsorption behavior of Ga, In and Tl on nanometer-size titanium dioxide by ICP-AES].

The adsorption behavior of nanometer TiO2 towards Gallium (Ga) Indium (In) and Thallium (Tl) was investigated with inductively coupled plasma atomic emission spectrometry (ICP-AES). The optimum conditions for adsorption were studied in detail, and the test included sorption kinetics, effect of pH on adsorption ratio, enrichment factor, and adsorption capacity. Under the optimum conditions, Ga (III), In(III) and Tl(I) ions could be adsorbed and recovered quantitatively. The static adsorption capacities of Ga(III), In(III) and Tl(I) on nanometer TiO2 were 48.6, 46.6 and 23.4 mg x g(-1) respectively. For the elution of Ga(III), In (III) and Tl(I), a mixture of 0.1 mol x L(-1) EDTA solution and 1.0 mol x L(-1) HNO3 was used, and the recovery ratio was above 92%. According to the definition of IUPAC, the detection limits (3sigma) of this method for Ga, In and Tl with an enrichment factor of 12.5 are 3.0, 6.0 and 13 ng x mL(-1), respectively; and relative standard deviations (RSD) are 1.85%, 1.96% and 3.4%, respectively (n = 6). The proposed method has been applied successfully to the analysis of geological samples with satisfactory results.

[Relationship study between the retention behavior on diverse gas chromatographic stationary phases and molecular structure information connectivity indices of PCDFs].

Based on the molecular valence connectivity index, atomic characteristic value(valence delta) delta iH is defined as: delta iH = mi.Zi.(Zi-hi).(8-Ni)(hi/(2.ni))/ [4.(Li + pi).(ni-1)]. Molecular valence connectivity index n chi H (n = 1,2,...,m) of atomic characteristic are set up with the delta iH:n chi H = sigma (delta iH. delta jH. delta kH..... delta mH)-0.5 and n chi H being defined as: 1 chi H = sigma (delta iH. delta jH)-0.5, 2 chi H = sigma (delta iH. delta jH. delta kH)-0.5. The 1 chi H, 2 chi H values of 135 polychlorinated dibenzofurans (PCDFs) molecules are calculated. It is found that 1 chi H or 2 chi H or 1 chi H and 2 chi H are correlated well with the retention behavior(RI and RRT) of gas chromatography for these compounds. Twelve models, each of which is constructed by using all sample sets, with high correlation coefficient, r > 0.96, are developed for three columns (DB-5, SE-54 and OV-101). It has been demonstrated that the method possesses the advantages of easy computation and clear physical significance.