A method for determination of iron in a
copper alloy comprises the following steps: (1) a
copper alloy sample is weighed and put into a conical flask, and HCl and H2O2 are used for heating to dissolve the sample; (2) the
copper alloy sample solution is taken and slightly cooled, an
ammonia solution is used to adjust pH value to 6.8-7.2, the
copper alloy sample solution is filtered and washed with the
ammonia water until the
copper alloy sample solution is free of copper ions, and
hydrochloric acid is used for washing a precipitate into a conical flask; (3)
tin dichloride is used for reduction of the solution to yellowish; then water is added, a mixed acid of
phosphoric acid and
sulfuric acid is added, a few drops of a
sodium tungstate indicator are added, and a
titanium trichloride solution is added dropwise until the solution is blue; then a
potassium dichromate standard
titration solution is used for
titration of the solution until the blue color disappears; then three drops of a
sodium diphenylaminesulfonate indicator are added, and the
potassium dichromate standard
titration solution is used for titration of the solution until a stable purple color as the end point is reached. The
reaction speed is fast, the end point is stable, does not
change color and is easy to observe, and the accuracy is good; meanwhile the determination process is short, determination efficiency is high, the determination method is easy to grasp, used chemicals are simple, and the method has the advantages of low
pollution, low requirements for equipment and environment and low determination cost.