Determination of Stannum Content in Tin-lead Solder by Complexometric Back Titration

Complexometric back titration was brought up to the determination of stannum content in tin-lead solder.Sample was treated by hydrochloric acid and nitric acid.Superfluous EDTA was added for complexation with stannum,lead and other elements.Hexamethylenetetramine was used to keep acidity at pH 5.5.EDTA of stannum was titrated by standard zinc chloride solution at pH 5.5,with xylenol orange as indicator.Then stannum content was attained,Influential factors of diffluence process,including the volume ratio of hydrochloric acid and nitric acid,method of regulating acidity,quantity of EDTA and water added,quantity of sodium fluoride added,disturbance of element were studied.Under the optimum conditions,approving result of two model samples was acquired.The range of recovery was 99.76%～100.5%.