Citric acid Method summary

Method summary
In glacial acetic acid as solvent, crystal violet as indicator, titrate with perchloric acid standard solution to the Calcium lactate purple to blue as the end point, to calculate the content in anhydrous form.
Weigh the dry matter A0.25g, accurate to 0.0002g, placed in a dry 250mL conical flask, add 40mL of glacial potassium lactate，  slightly heated and dissolved, cooled to room temperature, add 2 drops of crystal violet indicator solution with perchloric acid standard titration droplet to the solution from purple to blue as the end point. While doing a blank test.