Question: how to make dtnb stock solution?
Answer: Make 10mM DTNB stock solution by dissolving 40mg DTNB in 10ml DMSO. The stock solution can be stored at 4°C for 3 months. Dilute the stock solution 100 fold with 0.1M Tris-HCl pH 7.5 to make 0.1mM DTNB working solution.