| In this paper, the studies of most new separation and preconcentration methods have been reviewed; especially focus on the combination with spectrophotometry and separation methods, such as solid-liquid separation (i.e., resin phase spectrophotometry) and solvent flotation separation/ preconcentration (using inert gas as the flotation gas). These methods thave the characteristics of combination of separation, preconcentration and determination. Therefore, they are of high selectivity and sensitivity, and very suitable for the analysis of complex matrix samples, such as high purity samples, biological samples and environmental samples with very low concentration impurities. This paper includes following research work:(1) The traditional solid-phase spectrophotometry (for example, the resin-phase spectrophotometry) need a special cell, most of which is 1 mm long and have a hole at the bottom to release the solution for reducing the disturbance of dispersion. The disadvantages of complex operation steps, disturbance of dispersion, difficulty of fitting solid-phase in the cell, limitation of precision and accuracy, and relative poor sensitivity, lead to the limitation of the traditional solid-phase spectrophotometry. In this study, two new techniques were studied to overcome the shortcomings of the traditional solid-phase spectrophotometry. First, the decrease of the resin size could improve the viscosity and adsorbance surface. This method is to make the thin layer of resin into two quartz's glasses, instead of the normal quartz's cell. Therefore, the operation could be very easy achieved and the disturbance of dispersion could be avoided. Accordingly, the sensitivity and accuracy, as well as the precision, are significantly improved. This novel resin-phase spectrophotometry can be wildly applied in the determination of complex samples, especially of the environmental samples, with higher sensitivity.The study of the separation mechanism of ion-exchange resin and the preconcentration theory are still not very clear. As a result, the blindness of the experimental design would be occurred. In this work, the separation and preconcentration mechanism were discussed. The ternary or multi-association complexes, were simultaneous or asynchronous formed by the determinant ions, complexing agent and ion-exchange resin. And the infrared shift would be occurred under this condition.In this work, the influence of temperature, resin size and volume, adsorption and dry time were studied. The optimum operation condition were also obtained. The proposed method were applied in the determination of Fe, Co, Cu, Mg, Si, P, Bi, Cr, Mo, etc, in environmental samples.The further studies were the application of other adsorption materials, such as TiO2, SiO2, and the establishment of new thin-layer solid-phase spectrophotometry. The results of the study could also be applied in the loading of catalyst onto the ion-exchange resin, which could be applied in the organic synthesize.(2) The traditional flotation spectrophotometry are obtained with the combination of ions and complex agent, which formed the third phase on the inter face of the other two phases. Then the pretreat procedures (wash, resolution) are done prior to the spectrophotometry determination. The shortcomings of the traditional flotation technique are of difficult operation, low enrichment factor and relative poor sensitivity, accuracy and precision. In this work, the inert gas was used. Therefore, the formation of third phase will not occurred. Most of the analytes extracted into the top layer of organic reagent. As a result, the sensitivity and precision will improved significantly.The studies were focus on the partition mechanism of the inert gas on the inter face of two phases. The proposed method had been applied in the determination of Cr, Mo, Pb, Mn, Cu, Se, I-, Vc, sulfite etc., in environomental samples.The method was a replacement of the traditional extaction techniques. The reduce of organic reagent consumption and pollution, as well as the econom... |
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