I just purchased a kit for measuring Free S02 in solutions. The chemicals include hydrogen peroxide 3%, phosphoric acid 25%, sodium hydroxide 0.01N, and HCL 0.01N.
How long will the chemicals retain their correct concentration? What is a standard amount of time to replace them? 6 months?
I'm not a professional lab tech, so I just need a good rule of thumb to maintain a decent level of accuracy