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对于铜合金中锰的测定,常将Mn(Ⅱ)氧化为紫红色MnO_4~-,用经典的分光光度法测定。但由于铜溶液的背景干扰,使该法误差较大.故一般采取电解分离主体铜,或者采用二次测定以扣除Cu~(2+)背景吸收,但也有诸多不便。本文利用一阶导数分光光度法直接进行锰的测定,完全消除了铜合金中各种元素的干扰,方法简便快速,精密度和准确度都令人满意。一、主要试剂和仪器锰标准溶液:0.1mg/mL;混酸溶液:加10mL浓H_2SO_4于40mL水中,冷却后加25mL浓HNO_3,20mL浓H_3PO_4。加水至100mL,混匀;AgNO_3溶液:0.2％;(NH_4)_2S_2O_8溶液:10％(当天配用):水,将去离子水加热至沸,每升用10mL H_2SO_4(1+3)酸化,加几粒KIO_4,继续加热煮沸几分钟,冷却后使用。
For the determination of manganese in copper alloys, Mn (II) is often oxidized to magenta MnO 4 -, as determined by classical spectrophotometry. However, due to the background interference of copper solution, the error of this method is large, so the general use of electrolytic separation of the main copper, or the use of secondary determination to deduct Cu ~ (2+) background absorption, but there are many inconveniences. In this paper, direct determination of manganese by first-order derivative spectrophotometry completely eliminates the interference of various elements in the copper alloy, the method is simple and rapid, the precision and accuracy are satisfactory. First, the main reagents and equipment Manganese standard solution: 0.1mg / mL; mixed acid solution: add 10mL H_2SO_4 concentrated in 40mL of water, add after cooling 25mL HNO_3, 20mL H_3PO_4 concentrated. Add water to 100mL, mix; AgNO_3 solution: 0.2%; (NH_4) _2S_2O_8 solution: 10% (same day with): water, deionized water heated to boiling, with 10mL H_2SO_4 (1 +3) A few tablets KIO_4, continue to heat boil a few minutes, after cooling use.