I have been hired as a consultant to solve some manufacturing and instrumentation problems for a company that makes colloidal silver. One issue is they have chloride ion in solution that is destroying the nanoparticles over time. One batch I tested was ~27 ppm chloride ion, but I have no idea where in the manufacturing process the chloride is coming from (although i assume the water) or what the initial chloride concentration was before precipitation as silver chloride.

I need to solve this problem and could really use some recommendations on which chloride selective electrode to purchase. It is a small company so the cheaper the better. Potential interfering ions is primarily just Ag . I also could use some recommendations for the controller/console (sorry I forgot what they are called.)

Thanks for your help!