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錫基合金的組成为Sn、Cu、Sb和少量的Pb。銅的测定利用差减法:即部分試样溶液加入过量的EDTA,煮沸,使Sn、Cu等絡合(Sb不与EDTA絡合),然后調节pH为5～6以二甲酚橙为指示剂,以硝酸铅标准溶液回滴。另取同样体积的試样溶液加硫脲掩蔽銅,按上述操作进行回滴,根据两次耗用硝酸鉛毫升差数确定銅的含量。錫的测定是在上述滴定完的試液中加氟化銨解蔽
The composition of the tin-based alloy is Sn, Cu, Sb and a small amount of Pb. Copper determination using the subtraction method: that is, part of the sample solution was added excess EDTA, boiled, so that Sn, Cu and other complexes (Sb complexed with EDTA), and then adjust the pH of 5 to 6 xylenol orange as an indicator Agent, with lead nitrate standard solution back drop. Another sample of the same volume plus thiourea masking copper, according to the operation of the drop back, according to twice the consumption of lead nitrate milliliters to determine the difference between the amount of copper. Determination of tin in the titration of the test solution plus ammonium fluoride shelter