重铬酸钾容量法测定铁,因指示剂自身氧化而要多消耗滴定剂,且所用汞盐也污染环境。本文采用硫代硫酸钠滴定碘法,以双铂电极作工作电极通过电流变化判断终点,突跃明显。试液勿需分离,在pH4存在氟氢化铵条件下,仅滴定铜量;另在pH1.5条件下,滴定铜、铁合量,由两次消耗滴定剂的体积差计算铁量。滴定10毫克铜时,共存元素的允许量(毫克)为:钼(Ⅵ)、钙、氨(100),镉、汞(Ⅱ)、镍、铅、锌、铬(Ⅲ)、锡(Ⅳ)、钴、硅、铝、钨(Ⅵ)、钛(Ⅳ)(50),砷(Ⅴ)、锑(Ⅴ)、铁(Ⅲ)(10);钒(Ⅴ)的干扰可在 Potassium dichromate volumetric method for the determination of iron, because the indicator itself oxidizes and consumes more titrant, and the use of mercury salts also pollute the environment. In this paper, titration with sodium thiosulfate iodine method to dual-platinum electrode as the working electrode through the current change to determine the end point, sudden jump obvious. The test solution does not need to be separated, and only the amount of copper is titrated in the presence of ammonium bifluoride in the presence of pH 4; otherwise, the amount of iron is titrated for the amount of copper and iron by titration under the condition of pH 1.5. The allowable amount (mg) of coexisting elements when titrating 10 mg copper is molybdenum (VI), calcium, ammonia (100), cadmium, mercury, nickel, lead, zinc, chromium (III) (Ⅳ) (50), arsenic (Ⅴ), antimony (Ⅴ), iron (Ⅲ) (10); and vanadium (Ⅴ) can be found in