光度法测定大气中微量氯——基于对甲基橙的氧化褪色反应

Photometric Determination of Microamounts of Chlorine in Air Based on the Oxidation Color-fading Reaction with Methyl Orange

在稀硫酸介质中气态氯与吸收液中溴化钾反应所产生的溴将甲基橙试剂氧化褪色,根据其在515 nm波长处所测得的吸光度的下降程度(ΔA),间接地用光度法测定了空气中微量的氯。对采样量及采样时间、温度及时间对反应的影响,以及吸收液的酸度等对上述褪色反应有影响的因素作了较详细的试验并予以优化。

Microamounts of chlorine in air were determined photometrically by its reaction with KBr in a dilute Hz SO4 medium to liberate Br2 which in turn oxidize methyl orange （MO） leading to color-fading of MO and decrease of absorbance （△A） measured at the wavelength of 515 nm Factors influential to the color-fading reaction, including the amount and time of sampling, the blank test, time and temperature of the reaction, acidity of the absorbing solution and etc, were studied and optimized.