| The toxicity and the effect of trace elements on human health and the environment are receiving increasing attention in pollution and nutritional studies. Therefore, it is crucial to develop simple, rapid, and efficient methods for monitoring metal ions in the environment. In SPE procedure, the choice of appropriate adsorbent is a critical factor to obtain full recovery and high enrichment factor. To improve the selectivity, a chemical or physical modification of the sorbent surface with some organic compounds, is usually used to load the surface with some donor atoms such as oxygen, sulfur, nitrogen and phosphorus. Based on it, this research paper is devoted to the design, synthesis and application of newly selective solid-phase extractors in order to pre-concentration and separation of trace metal ions. The detailed novelty of this study has been listed in the following:1. A new selective solid-phase extractant using activated carbon as matrix which was purified, oxidized and modified by triethylenetetramine (AC-TETA) was prepared and characterized by FT-IR spectroscopy. At pH4, quantitative extraction of trace Cr(Ⅲ), Fe(Ⅲ) and Pb(Ⅱ) was obtained and determined by inductively coupled plasma optical emission spectrometry (ICP-OES). Complete elution of the adsorbed metal ions from the sorbent surface was carried out using0.5mol L-1HCl. The maximum static adsorption capacity of sorbent for Cr(Ⅲ), Fe(Ⅲ) and Pb(Ⅱ) was34.6,36.5and51.9mg g-1, respectively. The time of quantitative adsorption was less than2min. The detection limits of the method was found to be0.71,0.35and0.45ng mL-1for Cr(Ⅲ), Fe(Ⅲ) and Pb(Ⅱ), and the relative standard deviation (RSD) was3.7%,2.2%and2.5%, respectively. Moreover, the method was free from interference with common coexiting ions. The method was also successfully applied to the preconcentration of trace Cr(Ⅲ), Fe(Ⅲ) and Pb(Ⅱ) in synthetic samples and a real sample with satisfactory results.2. In this study, Cr(lII), Cu(Ⅱ), Cd(Ⅱ) and Pb(Ⅱ) have been preconcentrated and separated by a new sorbent using rhodamine6G modified oxidized activated carbon and characterized by Fourier transform infrared spectra. At pH4, quantitative extraction of trace Cr(Ⅲ), Cu(Ⅱ), Cd(Ⅱ) and Pb(Ⅱ) was obtained and determined by ICP-OES. The adsorbed metal ions were completely eluted by1.0mol L-1HCl. The method was free from interference with common coexisting ions. The maximum adsorption capacity of the adsorbent at optimum conditions was found to be37.8,47.8,56.5and41.7mg g-1for Cr(Ⅲ), Cu(Ⅱ), Cd(Ⅱ) and Pb(Ⅱ) at pH4, respectively. The detection limits of the method were under0.35ng mL"1and the relative standard deviations were lower than3.5%(n=11). The method was validated using a standard reference material, and has been applied for the determination of trace Cr(Ⅲ), Cu(II), Cd(Ⅱ) and Pb(Ⅱ) in biological and natural water samples with satisfactory results.3. The study on the high efficiency of triocarbohydrazide modified attapulgite as solid-phase extractant for preconcentration of trace Au(Ⅲ) prior to the measurement by ICP-OES has been reported. Experimental conditions for effective adsorption of trace levels of Au(Ⅲ) were optimized with respect to different experimental parameters using batch and column procedures in detail. At pH3, Au(Ⅲ) could be quantitatively adsorbed on the new sorbent, and the adsorbed Au(Ⅲ) could be completely eluted from the sorbent surface by2.0mL1.0mol L-1of HCl+2%CS(NH2)2solution. An enrichment factor of150was accomplished. Moreover, common interfering ions did not interfere in both separation and determination. The maximum adsorption capacity of the sorbent for Au(Ⅲ) was found to be66.7mg g-1. The detection limits (3σ) of this method was0.32μg L-1and the relative standard deviation (R.S.D.) was3.3%(n=8). The method, with high selectivity, sensitivity and reproducibility, was validated using certified reference materials, and had been applied for the determination of trace Au(Ⅲ) with satisfactory results.4. A new method of separation, preconcentration and determination of trace gold(Ⅲ) in water samples was developed based on utilized1-amino-2-naphthol-4-sulfonate modified activated carbon as a solid-phase sorbent and measured by ICP-OES. The new sorbent was confirmed by Fourier transform infrared spectra. Experimental conditions for effective adsorption of trace gold(Ⅲ) were optimized in details. At pH3, gold(Ⅲ) could be quantitatively adsorbed on the new sorbent, and the adsorbed gold(Ⅲ) could be completely eluted from the sorbent surface by2.0mL of1.0mol L-1of HC1+2%CS(NH2)2. An enrichment factor of200was accomplished. The maximum adsorption capacity of the sorbent for gold(Ⅲ) was found to be32.3mg g-1. Moreover, common electrolytes did not interfere with the adsorption and determination of the analytes. The detection limit (3σ) of this method was found to be0.26ug L-1, and the relative standard deviation (R.S.D.) was3.1%(n=8). The method, with high certified selectivity, sensitivity and reproducibility, was satisfactorily applied to determinate a reference materials and water samples.5. At pH7.4, the resonance light scattering (RLS) intensity of the interaction of europium(Ⅲ) with proteins was obviously enhanced in wavelength range of250-600nm. When the pH value is higher than the isoelectric point of protein in Palitzsch buffer solution (pH7.4), protein takes negative charge. So the electrostatic interaction between europium(Ⅲ) and proteins may occur. Based on the phenomenon, a new simple, sensitive and selective method for the determination of proteins has been developed. Under the optimum condition, the enhanced RLS intensities were proportional to the proteins concentration over the ranges0.16-30.00and0.05-20.00ug mL-1for hemoglobin (Hb) and immunoglobulin G (IgG), respectively. The corresponding limits of detection were80and22ng mL-1for Hb and IgG, respectively. Moreover, the method was free from interference with many metal ions and animo acids. Synthetic samples were satisfactorily determined with the recovery of97.5-103.2%. |
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