The conventional determination method for biochemical oxygen demand (BOD) was improved. With I3 - -methyl violet-polyvinyl alcohol spectrophotometric system, the concentration of dissolved oxygen before and after sample treatment was determined. Potassium iodate and excessive potassium iodide generated I3 which formed with methyl violet an ion complex with maximum absorption at 550 nm. BOD5 could be worked out with the content of dissolved oxygen determined by spectrophotometry before and after 5 days treatment. The proposed method was applied to the determination of BOD5 in standard sample solution, glucose-glutamic acid standard solution and the influent and effluent water from waster water factory. The results were consitent with those by national standard method of China.%对传统的生化需氧量(BOD)测定方法进行了改进,采用I3-结晶紫-聚乙烯醇体系光度法测定样品培养前后的溶解氧浓度,实验以碘酸钾与过量碘化钾生成单质碘,新生成的I3-与结晶紫生成的离子缔合物在550 nm处有最大吸收,采用光度法测定5天前后培养水样中溶解氧的含量来计算水样中BOD5.所拟方法用于BOD3标准样品溶液、葡萄糖-谷氨酸标准溶液和污水厂进出口水样中BOD3的测定,结果与国家标准方法所得结果一致.
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