Method for measuring tin element by EDTA (Ethylene Diamine Tetraacetic Acid) complexation

Abstract

The invention relates to a method for measuring tin elements, comprising the following steps of: deoxidating a sample; dissolving with the mixed acid of hydrochloric acid and nitric acid; adjusting acidity of the solution with ammonia water and the hydrochloric acid; quantificationally complexing the tin and other elements capable of complexing with EDTA with excessive EDTA; with xylenol orange as an indicator, titrating excessive EDTA with the standard titration solution; buffering with hexamethylene tetramine to ensure that the pH value is between 5 and 6; adding sodium fluoride for separating out EDTA which is equivalent to the amount of the tin; titrating separated EDTA with the standard titration solution until the solution becomes red from yellow; and calculating the percentage of the tin according to the volume of the standard titration solution consumed in the second titration. The method has the recovery rate of 95.54-104.76% and the relative standard deviation of 1.41-2.67%. The reagents used in the method are all common chemical reagents, and no special devices are needed. In addition, the method has the advantages of simple process, short measurement period and low cost.

Description

technical field [0001] The invention belongs to the field of chemical analysis of metal materials and relates to a method for determining tin element. Background technique [0002] Among the existing tin-lead solder analysis methods, there are three commonly used methods: [0003] 1. Potassium iodate titration: The sample is decomposed with sulfuric acid and potassium bisulfate. In hydrochloric acid solution, tetravalent tin is reduced to divalent tin with iron powder and aluminum powder or lead sheet. Using starch as indicator, titrate with potassium iodate standard solution until the test solution turns light blue as the end point. Pure carbon dioxide gas and a reduction device are used in the test, the steps are cumbersome, the device is complicated, and the lead sheet used is poisonous, which will pollute the environment. [0004] 2. Atomic absorption spectrometry: tin can be determined by air-acetylene flame, but there are many coexisting elements such as lead and an...

AI Technical Summary

Problems solved by technology

Pure carbon dioxide gas and a reduction device are used in the test. The steps are cumbersome and the device is complicated. The lead sheet used is poisonous and will pollute the environment.

[0004] 2. Atomic absorption spectrometry: tin can be determined by air-acetylene flame, but there are many coexisting elements such as lead and antimony in tin-lead solder, which interfere with the determination of tin, and the error of the test value is large, which cannot be accepted

However, since many metal elements can be complexed with EDTA, it is difficult to distinguish the elements to be tested from the interfering elements, so its selectivity is a big problem

In the original method of using EDTA to determine tin, the test conditions are relatively general, especially the restrictions on the determination conditions are relatively loose, so it is difficult to guarantee the accuracy and stability of the determination results

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