Simple operation scheme for quantitative detection of heavy metal ions

According to you, just replace the standard hydrochloric acid solution used for titration of alkali in the original device with a solution that can test the ions you need.

Then copper ions are titrated with sodium hydroxide solution with inhibitory concentration, and the phenomenon of complete reaction is that the blue color of the solution disappears or no blue precipitate is produced.

Iron can also be used in sodium hydroxide solution, the phenomenon is that the solution becomes colorless or does not produce reddish-brown precipitation.

When there is no precipitation in the solution, check the amount of sodium hydroxide added dropwise. Since the concentration of sodium hydroxide (R 1) is known, the dropping volume (V 1) is known, and the volume of the solution to be tested (V2) is known, you should find the concentration of the solution to be tested, just like acid-base titration.