When using cuvettes, ensure that the two transparent surfaces are completely parallel and placed vertically in the cuvette holder. This ensures that the incident light is perpendicular to the transparent surface during measurement, avoiding losses due to light reflection and ensuring a fixed light path. Cuvettes are generally rectangular prisms with frosted glass on the bottom and sides and optical glass on the other two sides, bonded to form transparent surfaces. Therefore, please note the following points when using:

1. When taking cuvettes, only touch the frosted glass on both sides with your fingers, avoiding contact with the optical surface.
2. Do not allow the optical surface to come into contact with hard objects or dirt. When filling the solution, fill it to about 2/3 of the height of the cuvette. If there is residual liquid on the optical surface, gently absorb it with filter paper, and then wipe it with lens paper or silk.
3. Solutions containing substances that corrode glass should not be stored in cuvettes for an extended period.
4. After using cuvettes, rinse them immediately with water. If necessary, soak them in a 1:1 hydrochloric acid solution, and then rinse with water.
5. Do not place cuvettes on a flame or on a heating element for drying.
6. Before use, soak cuvettes in a 2% nitric acid solution for 24 hours, then rinse with water and distilled water in sequence, and dry.
7. Before colorimetry, fill each cuvette with distilled water, compare them at the colorimetric wavelength, and select 4-8 cuvettes with an absorbance error within ±0.001 for colorimetric determination to avoid measurement errors caused by cuvette differences.
8. When pouring liquid into cuvettes, tilt them along the frosted surface and pour slowly. Do not invert the cuvettes. Place them with the mouth facing down on clean filter paper to absorb the remaining liquid. Then rinse the inside of the cuvettes with distilled water, pouring it out along the frosted surface (same operation as above). This prevents liquid spillage, allowing for the second measurement without wiping the cuvettes, avoiding errors introduced by wiping.