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本文采用氨性介质中以柠檬酸、EDTA为掩蔽剂用甲基异丁基酮(MIBK)萃取铜试剂银的络合物,有机相喷雾原子吸收法测定岩石中微量银。试验确定:pH6.7～9.5,铜试剂5～50毫克,柠檬酸2～12克和EDTA1～6克均能定量萃取银。用此介质能掩蔽大量基体元素,用于硅酸盐或铁矿时取样可以大至2克,且不需予分离。虽然铜试剂对金属离子选择性差,但其与银形成的络合物有很高的萃取常数,控制铜试剂用量,能优先定量萃取银,在上述条件下能将1.5克三氧化二铁保留在水相中,仅极小部分被萃取(<0.1毫克)。与银同时被萃取的有钯、汞、铋等,但岩石中含量极微,不影响测定。铜
In this paper, the complex of copper reagent silver was extracted with MIBK by using citric acid and EDTA as masking agent in ammoniacal medium, and the trace silver in rock samples was determined by organic phase spray atomic absorption spectrometry. The experiment confirms that the silver can be quantitatively extracted from pH6.7 ~ 9.5, copper reagent 5 ~ 50 mg, citric acid 2 ~ 12g and EDTA1 ~ 6g. With this medium it is possible to mask a large number of matrix elements and to sample up to 2 g for silicate or iron ore without the need for separation. Although copper reagents have poor selectivity for metal ions, they have high extraction constants for complexing with silver and control the amount of copper reagent to give priority to the quantitative extraction of silver. 1.5 g of ferric oxide remains under the above conditions In the water phase, only a very small fraction is extracted (<0.1 mg). With silver is also extracted with palladium, mercury, bismuth, etc., but the rock content is minimal, does not affect the determination. copper