1-Naphthyl acetate is usually used in a rapid staining method for identification of macrophages. 1-Naphthyl acetate is a potent chromogenic substrate for the detection of erythrocyte acetylcholinesterase (AChE) activity. It has the potential to detect organophosphorus pesticide poisoning.

Experimental method
I. Solution preparation
1. Prepare 1-Naphthyl acetate solution, usually dissolved in ethanol or DMSO, with a concentration of 1-10 mM.
2. Prepare a colorimetric agent (such as Fast Blue B) and dilute to the working concentration as needed;
II. Red blood cell preparation
Collect fresh blood, wash the red blood cells 2-3 times with saline, centrifuge to remove plasma and white blood cells, and finally resuspend with an appropriate amount of buffer.
III. Operation steps
1. Add an appropriate amount of red blood cell suspension (usually 100-200 μL) to the reaction tube.
2. Add 1-Naphthyl acetate substrate solution to a final concentration of 0.1-1 mM.
3. Add an appropriate amount of colorimetric agent and mix well. Incubate the reaction system in a 37℃ water bath for 15-30 minutes.
4. After the reaction is completed, add an appropriate amount of stop solution (such as glacial acetic acid) to terminate the reaction;
5. Result detection: Use a spectrophotometer to measure the absorbance of the color product at a wavelength of 540-560 nm; or observe the staining of red blood cells under a microscope.
6. Data analysis: Calculate the acetylcholinesterase activity based on the absorbance value. The activity is proportional to the absorbance of the color product.