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二氧化硫是一种重要的工业用气体,也是一种重要的大气污染物,它通常是用汞盐来测定的。本文作者研究出一种不使用危险汞盐的测定方法。二氧化硫被吗啉[NH(CH_2)_(?)O(CH_2)_2]溶液吸收,然后再与过量的酸性重铬酸盐溶液混合,重铬酸盐中的六价铬被二氧化硫还原为三价铬。用二苯碳酰二肼[CO(NH·NH·C_6H_5)_2]测定六价铬。生成一种可溶性红紫色络合物,它在540nm 处有最大吸收峰。当用试剂作空白时,还原反应后所产生红紫色络合物的吸光度的减少,是与用于还原反应的二氧化硫的浓度成正比的。当溶液中二氧化硫的浓度在0.4～4υg/ml 范围时,比耳定律是适用的。
Sulfur dioxide is an important industrial gas, but also an important atmospheric pollutant, which is usually measured with mercury salts. The authors developed a method that does not use hazardous mercury salts. Sulfur dioxide is absorbed by the morpholine [NH (CH 2) O (CH 2) 2] solution and then mixed with excess acidic dichromate solution. The hexavalent chromium in the dichromate is reduced to sulfur trioxide chromium. Hexavalent chromium was measured with diphenylcarbazide [CO (NH.NH.C_6H_5) _2]. A soluble magenta complex was formed which had the maximum absorption at 540 nm. When reagents are used as blanks, the reduction of the absorbance of the magenta complex produced after the reduction reaction is proportional to the concentration of sulfur dioxide used for the reduction reaction. Beer’s law is applicable when the concentration of sulfur dioxide in the solution is in the range of 0.4 to 4 μg / ml.