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铁基材料中,含钼、镍及轻稀土氧化物的量各为百分之几.以偶氮胂Ⅲ为发色剂,进行稀土含量测定时,有过量EDTA(存在Fe—EDTA)时,在pH2.4附近吸光度最高,说明此时EDTA干扰最小;稀土偶氮胂Ⅲ吸光度从pH1到pH2.4逐渐升高,pH2.4到5.0不变,可见在pH2.4时,稀土偶氮胂Ⅲ已充分发色;Fe—EDTA吸光度随pH增大而增高,pH2.4吸光度为0.003,可忽略不计,用试剂空白代替.pH由3.0降到pH2.4时,Fe—EDTA的pK值降低很小,而稀土—EDTA的pK值则降低较多,说明pH2.4时,EDTA对稀土—偶氮胂Ⅲ络合物生成干扰小,与试验结果一致.在测定条件下,EDTA掩蔽大量镍及5mg铁;EDTA—磺基水杨酸掩蔽15mg铁和0.3mg镍;
Iron-based materials, the amount of molybdenum, nickel and light rare earth oxides are each a few percent.With arsenazo Ⅲ as a hair dye, rare earth content determination, there is excessive EDTA (Fe-EDTA) At pH 2.4 near the highest absorbance, indicating EDTA interference at this time the smallest; rare earth arsenazo Ⅲ absorbance gradually increased from pH1 to pH2.4, pH2.4 to 5.0 unchanged, can be seen at pH2.4, rare earth arsenazo Ⅲ has been fully hair color; Fe-EDTA absorbance increased with increasing pH, pH2.4 absorbance of 0.003, negligible, reagent blank instead of.pH decreased from 3.0 to pH2.4, Fe-EDTA pK value decreased Was small, while the pK value of rare earth-EDTA decreased more, indicating that EDTA had less interference with rare earth-arsenazo III complex at pH 2.4, consistent with the experimental results.Under the conditions of measurement, EDTA masked a large amount of nickel And 5 mg iron; EDTA-sulfosalicylic acid masked 15 mg iron and 0.3 mg nickel;