Spectrophotometer using steps
- Warm up the spectrophotometer. In order to make the measurement stable, turn on the power switch and preheat the spectrophotometer for 20 minutes. In order to prevent the fatigue of the photocell, do not continue to illuminate. When preheating the instrument and when not measuring, the cuvette dark box cover should be opened to cut off the light path.
- Selected wavelength. According to the requirements, turn the wavelength adjuster to make the pointer indicate the desired wavelength of monochromatic light.
- Fixed sensitivity file. According to the absorption of light by the colored solution, in order to make the absorbance reading 0.2-0.7, select the appropriate sensitivity. For this reason, turn the sensitivity file to fix it at a certain file, and it will not change during the experiment. The general measurement is fixed at the "1" file.
- Adjust the "0" point. Gently turn the "0" potentiometer so that the pointer of the reading meter is exactly at the position where the light transmittance is "0" (at this time, the cuvette obscura cover is opened, the light path is cut off, and the photocell is not exposed to light).
- Adjust T=100%. Put the cuvette containing distilled water (or blank solution or pure solvent) into the first compartment of the cuvette stand, and the colored solution in the other compartments, gently cover the cuvette dark box cover, turn the light volume Adjust the light transmittance to T=100%, that is, the pointer on the meter head is exactly at T=100%.
- Determination. Gently pull the pull rod of the cuvette holder to make the colored solution enter the light path, and the pointer on the meter head shows the absorbance A of the colored solution. After reading, open the cuvette obscura cover.
- Shutdown. After the experiment, cut off the power, take out the cuvette and clean it, and wipe the cuvette holder and obscura with soft paper.
Precautions for using a spectrophotometer
- Before using the spectrophotometer, the user should first understand the structure and working principle of the spectrophotometer, as well as the functions of each control knob. Before turning on the power, you should check the safety performance of the instrument. The power wiring should be firm, and the power should be good. The initial position of each adjustment knob should be correct and then press the power switch.
- The spectrophotometer should be placed in a dry room, placed on a firm and stable workbench when in use, and the indoor lighting should not be too strong. In hot weather, do not use an electric fan to blow directly on the instrument to prevent the filament of the bulb from shining unstable.
- When the spectrophotometer is not connected to the power supply, the pointer of the ammeter must be on the "0" mark line. If this is not the case, it can be adjusted with the adjustment screw on the ammeter.
- To prevent photocell fatigue. When not measuring, the cover of the cuvette obscura must be opened to cut off the light path to prolong the service life of the photocell.
How to use cuvettes?
- When holding the cuvette, fingers can only pinch the frosted glass surface of the cuvette and do not touch the light-transmitting surface of the cuvette to avoid contamination.
- When cleaning the cuvette, generally rinse it with water first, and then wash it with distilled water. If the cuvette is contaminated by organic matter, it can be soaked in a mixed washing solution of hydrochloric acid and ethanol (1:2) for a while, and then rinsed with water. Do not wash the cuvette with alkaline solution or strong oxidizing washing liquid to avoid damage. Do not use a brush to clean the cuvette, so as not to damage its light-transmitting surface. After each experiment, the cuvette should be washed immediately.
- Blot the water on the outer wall of the cuvette with lens cleaning paper or soft absorbent paper to protect the light-transmitting surface.
- When measuring the absorbance of the colored solution, be sure to wash the inner wall of the cuvette several times with the colored solution to avoid changing the concentration of the colored solution. In addition, when measuring the absorbance of a series of solutions, they are usually measured in order from dilute to concentrated to reduce measurement errors.
- In the actual analysis work, usually according to the different concentrations of the solution, select the cuvette with different thicknesses of the liquid tank, so that the absorbance of the solution is controlled at 0.2-0.7.
The sisico spectrophotometer provides accurate data for measurements, allowing users to formulate, evaluate and control color more effectively.