水汽系统铁含量快速测定对及时了解热力系统腐蚀状况非常重要,但痕量铁常规测试方法繁琐或不便现场操作.流动注射(FIA)-TPTZ分光光度法测定水汽中痕量总铁的方法(简称FIA-TPTZ分光光度痕量铁测试法)快速简便,为使该法检出下限降低,对影响该法灵敏度的各主要因素,如试剂泵速、载流泵速、显色盘管长度、缓冲液pH值、水样pH值等进行深化研究.改进后的FIA-TPTZ分光光度痕量铁测试法,在0.5～100 μg/L质量浓度范围内,标准曲线线性回归系数大于0.999,相对标准偏差小于1.0％,检出下限由22.7 μg/L降低至0.5 μg/L,分析速度为60样/h,与现行国标法相比相对误差小于10％,适用于电厂水汽样品中痕量铁的自动快速检测,且易于实现在线监测.%It is of great importance to quickly determine the trace total iron in the water-steam system to figure out the corrosion status of the thermal system in a timely manner.Unfortunately the procedures of conventional method are too complicated and inconvenient to perform field testing.The flow injection analysis (FIA)-TPTZ spectrophotometry is proposed in this paper as a quicker and simpler way to determine the trace total iron in the water.In order to further improve this method to detect the trace total iron below the lower limit,the in-depth study is carried out on the major factors affecting the sensitivities,such as the reagent and carrier pump speeds,the colour coil length and the pH values of buffer solution and samples.After such improvements,in the range of 0.5～100 μg/L,the liner regression coefficient is now above 0.999,the RSD less than 1.0％,and the detection limit is extended down to 0.5 μg/L from previous 22.7 μg/L,with the detection rate at 60 samples per hour.The relative error is less than 10％ in comparison with the current standard method.Therefore,it is suitable for automatic detection of trace iron and easy to be applied for on-line monitoring.
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