二苯胺磺酸钠作为测铁的指示剂,本身被氧化要消耗重铬酸钾标准液。因此,消耗值的确定,关系到分析结果的可靠性。国家标准铁矿石分析方法空白值的测定,是有缺陷的,如用0.05毫升硫酸亚铁铵(约0.05N)进行分析,然后减去空白值,往往得负数。我们在测定指示剂校正值中,发现二苯胺磺酸钠消耗重铬酸钾的量随铁量而增加。因此当溶液中无铁或含铁极微时,不应当减空白值,而应当分段校正二苯胺磺酸钠消耗重铬酸钾标准液的量. 表中所列为不同量硫酸亚铁铵(0.05N)各加入不 Sodium diphenylamine sulfonate as an indicator of iron, itself oxidized to consume potassium dichromate standard solution. Therefore, the determination of consumption value is related to the reliability of the analysis results. National standard iron ore analysis blank value determination, is flawed, such as with 0.05 ml ammonium ferrous sulfate (about 0.05N) for analysis, and then minus the blank value, often negative. We measured the indicator correction value and found that the amount of potassium dichromate consumed by sodium diphenylamine sulfonate increased with the amount of iron. Therefore, when the solution is iron-free or iron-containing micro, should not be reduced blank white value, but should be subdivided to correct the amount of sodium dianhydride potassium dichromate standard solution.A list of different amounts of ammonium ferrous sulfate (0.05N) each added not