1. The pure HPMC aqueous solution of hydroxypropyl methylcellulose is clear, has high light transmittance, and the water retention rate is >95%; the adulterated HPMC aqueous solution is turbid, and the water retention rate is difficult to reach 80%.
2. Pure hydroxypropyl methylcellulose HPMC powder is fibrous under a microscope or magnifying glass; adulterated HPMC can be observed in granular solids or crystals under a microscope or magnifying glass.
3. Take the same two samples of hydroxypropyl methylcellulose and place them on the mirror surface. Then ignite it with fire. After the burning is finished, look at the ash left on the mirror. After burning pure hydroxypropyl methylcellulose, the bottom plate is flat. The adulterated hydroxypropyl methylcellulose chassis is convex. The flatter the burning chassis, the better the cellulose.