KCl (0.2 n, pH 6.8)
Prepare 100 mL of 0.2 n KCl. Adjust the pH to 6.8 with 0.05 m KOH. (The pH will overshoot and then gradually fall, so it can take about 3 h to stabilize to pH 6.8.) Filter-sterilize the solution. Store at room temperature for several months.










