Take the supernatant, add anthrone formaldehyde and H 2 SO 4 to react, and place in a boiling water bath for 1 minute. After cooling, the absorbance at 625 nm was measured.
Take the liquid, add the ketone formaldehyde and H 2 SO 4 reaction, and place in a boiling water bath for 1 minute. After cooling, the absorbent degree at 625nm is measured.
Take the supernatant, add anthrone formaldehyde to react with H 2SO 4, and put it in boiling water bath for 1 minute. After cooling, the absorbance at 625nm was determined.<br>