Hi, I want to ask everyone.
So I have a project to measure the content of several types of metals in water such as nickel, lead, and others. Are there any suggestions for sensors that I can use and can be applied to Arduino?
Thanks
Maybe a TDS sensor could do the job?
I have used a TDS sensor, but the TDS sensor only measures how much solids are in the water. If there is a sensor that can measure the amount of other metals specifically like how much lead or nickel is in the water.
Thanks for the advice.
I understand, but I'm sorry, I have no idea (except for more sophisticated and expensive sensors like spectrometry and electrochemical methods, not at Arduino level).
Ion selective electrodes are available for some metals They are not cheap and require an amplifer. See
I doubt you will find anything aimed at the hobby market (read: cheap) for this purpose.
A portable XRF with a USB data connection would be the tool for the job.
You find "hobby sensors" only if your metals are in non dissolved form like coins, nails, rings.... 
Wow. Thank you all very much. I think I got some additional information from the information you guys provided. I think I will dig deeper into these sensors.