EDTA滴定法与原子吸收光谱法相结合测定多金属矿中锌

Determination of zinc in polymetallic ore by combination of EDTA titration and flame absorption spectrometry

样品以硫酸铵-氢氧化铵一次沉淀分离后,用EDTA络合滴定法测定溶液中的锌含量,并将沉淀以盐酸溶解后用原子吸收光谱法测定其中吸附的锌含量,二者之和为样品中锌的总含量,提出了一种EDTA滴定法和原子吸收光谱法相结合测定多金属矿中锌含量的新方法,从根本上克服了絮状胶体沉淀等对锌的吸附。实验表明,在氨性介质中,铁锰等元素的沉淀会对溶液中的锌产生吸附,使锌的测定结果偏低,铅、镉也会对锌的测定造成影响。而采用本方法测定铅锌矿标准物质和锌精矿标准物质中锌的含量,测定值与认定值一致,相对标准偏差(RSD)小于0.4%。

After precipitation separation by ammonium sulphate-ammonium hydroxide, the content of zinc in the solution was determined by EDTA complexometric titration. Simultaneously, after the pre- cipitate was dissolved with hydrochloric acid, the content of the adsorbed zinc in the precipitate was determined by atomic absorption spectrometry. The sum of the both above was the total content of zinc in the sample. Consequently, a novel method for determination of zinc in polymetallic ore was proposed by the combination of EDTA titration and flame absorption spectrometry, which overcame the adsorption of zinc by flocculent colloidal precipitation fundamentally. The experiments showed that in the ammonia medium, the precipitation of iron and manganese and other elements Could adsorb zinc in the solution, leading to a lower determination result, and lead, cadmium also affected the de- termination of zinc. This method was applied to determine zinc in lead zinc ore and zinc concentrate certified reference materials. The results were in accordacnce with the certified values, and the rela- tive standard deviations （RSDs） were less than 0.4%.