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Silica gels modified with 3-aminopropyltriethoxysilane or 3-mercaptopropyltrimethoxysilane groups have been developed for the preconcentration of copper and cadmium prior to their determination by flame atomic absorption spectrometry. The surface areas of the modified silica gels were determined by the Brunauer-Emmett-Teller (BET) method to be 290 m2 g-l of the amino-modified silica and 410 m2 g-1 of the thiol-modified silica. Batch and column methods were used for the separation and concentration of copper and cadmium. These metals were quantitatively retained on both the modified gels in slightly acidic media. In the batch method, the effects of pH, shaking time and type of buffer on the adsorption of copper and cadmium were investigated. In the batch and column procedures both copper and cadmium adsorbed on the silicas were quantitatively recovered (relative standard deviation of 2-6%) using 2 mol dm-3 hydrochloric acid even in the presence of sodium chloride up to a concentration of 1 .O%.

The preparation and characteristics of thiol-modified silica and its application to the preconcentration and determination of trace amounts of copper and cadmium by flame atomic absorption spectrometry are described. For the preparation of modified silica, the untreated silica suspended in methanol was impregnated with 3-(trimethoxysilyl)-1-propanethiol to obtain thiol-modified silica and the methanol was evaporated under vacuum. The residual silica was dried at 150° C and washed with distilled water until the washings appeared clear. The surface area of thiol-modified silica was 410 m2/ g, whereas the copper capacity was about 0.022 mmolCu/ g silica. Batch and column methods were used for the separation and concentration of the above-mentioned metals. These metals were quantitatively retained on the adsorbent at acidic media. In the batch method, the effects of pH, shaking time and the kind of buffer on adsorption of copper and cadmium were investigated. The shaking time of 30 min was sufficient for a quantitative adsorption of the metals. In the column and batch procedures, both copper and cadmium adsorbed on the modified silica were quantitatively recovered with 2 M hydrochloric acid. Sodium chloride (up to 1%) had no effects on the recoveries.

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Objective: Trace elements such as manganese (Mn), cobalt (Co) and chromium (Cr) play key roles in metabolic reactions and are important in many physiological enzymatic processes. In this study, we aimed to investigate the acute effects of moderate and strenuous running (treadmill) exercise on the levels of Mn, Co and Cr in the brain, liver, and spleen of trained rats.Study Design: Animal experiment.Material and Methods: Twenty-one Wistar-Albino adult male rats were used in the study. Rats were grouped as control group (no mandated exercise; n=8), moderate exercise group (30 min exercise duration; n=7), and strenuous exercise group (60 min exercise duration; n=6). The levels of Mn, Co, and Cr in the frontal lobe, temporal lobe, brain stem, liver, and spleen were determined by atomic absorption spectrophotometer.Results: Cr levels in liver of rats increased in parallel to the time course of running supporting the exercise training effect on the action of insulin. Compared to the control group, the level of Co significantly decreased in the brain stem of rats in the moderate exercise group (p=0.009) and in the frontal lobe of rats in the strenuous exercise group (p=0.004). In the strenuous exercise group, an examination of the brain stem revealed that the level of Mn significantly decreased (p=0.001), and levels of Co and Cr were apparently depleted to the extent that these elements were no longer detectable. Conclusion:A notable finding is that during or after single bout strenuous exercise, levels of Co decreased in the spleen and particularly decreased in the brain stem of regularly trained rats. From this study, it can be inferred that sportsmen should aware trace element disturbances among the body parts or depletion of some trace elements after single bout of chronic strenuous running exercise.