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磷化溶液中含磷酸、锌、钙、锰、铁等,其中硝酸钙的测定原系采用三乙醇胺、氰化钾联合掩蔽锰、锌、铁等干扰元素后于pH大于12时用EDTA滴定,终点变化不很敏锐,尤其是锰、铁含量较高时观察更为困难,而使测定结果波动。间氯偶氮安替比林是测定钙的选择性较佳的新显色剂,应用于磷化溶液中钙的光度法测定有很好的效果。于氢氧化钠介质中试剂与钙形成1:1的蓝色络合物,在640nm波长附近有最大吸收,在测定条件下摩尔吸光系数为1.95×10~4,钙浓度在150μg·50ml~(-1)时采用差示光度法符合比耳定律。磷化溶液中其他共存成分均不干扰而能直接显色测定。
Phosphating solution containing phosphoric acid, zinc, calcium, manganese, iron, etc., of which the original determination of calcium nitrate with triethanolamine, potassium cyanide combined masking manganese, zinc, iron and other interfering elements at pH greater than 12 with EDTA titration, End point changes are not very sensitive, especially manganese, iron content is higher observed more difficult, leaving the measurement results fluctuate. Inter-chloroantipyrine is a new colorimetric reagent for the determination of calcium selectivity. It has good effect in the determination of calcium in phosphating solution. Reagents and sodium form a 1: 1 blue complex in sodium hydroxide medium with maximum absorbance at 640nm wavelength, molar absorptivity of 1.95 × 10 ~ 4 and calcium concentration of 150μg · 50ml ~ ( -1) when using differential spectrophotometry Beer’s law. Phosphate solution coexist in other components do not interfere with the direct color determination.