Visible spectrophotometer and its use method and steps

1. Principle
The basic principle of 　　 spectrophotometer is that the substance will produce the effect of light absorption under the irradiation of light, and the absorption of light by the substance is selective. Various substances have their own absorption spectra. Therefore, when monochromatic light of different wavelengths passes through the solution, the light energy will be absorbed in different degrees. The degree of light energy absorption has a certain proportional relationship with the concentration of the substance, which conforms to Beer's law.

Visible spectrophotometer and its use method and procedure

Among them: T—transmittance A—absorbance I0—incident light intensity a—absorption coefficient

I—Intensity of transmitted light b—Optical path length of solution c—Concentration of solution

It can be seen from the above formula that when the absorption coefficient a and the optical path length b are constant, the absorbance is proportional to the solution concentration. This instrument is designed based on this principle

Two, use
This instrument can be used for scientific research in physics, chemistry, medicine, biology and other disciplines or for the qualitative and quantitative analysis of various substances in the chemical industry, food industry, pharmaceutical industry, metallurgical industry, clinical biochemistry, and environmental protection departments.

The usage method of 　　 visible spectrophotometer is as follows:
Visible spectrophotometer instrument working power is generally 220V, allowing 10% voltage fluctuation, in order to prolong the life of the light source, do not turn on the light source lamp when not in use. The monochromator is part of the instrument and cannot be disassembled when it is installed in a sealed box. In order to prevent the dispersive element from being damp and moldy, the egg colorer box desiccant must be replaced frequently.

(1) The working power of the spectrophotometer is generally 220V, and 10% voltage fluctuation is allowed.

(2) In order to prolong the service life of the light source, do not turn on the light source lamp when it is not in use.

(3) The monochromator is a part of the instrument and cannot be disassembled when it is installed in a sealed box. In order to prevent the dispersion element from being damp and moldy, the monochromator box desiccant must be replaced frequently.

(4) The absorption cell must be used correctly to protect the optical surface of the absorption cell.

(5) The photoelectric conversion element should not be exposed to light for a long time, and it should be avoided from strong light irradiation or damp and dust.

Visible spectrophotometer and its use method and steps

The specific operation process of 　　 visible spectrophotometer is as follows:
1. Turn on the visible spectrophotometer

1. Before starting up, check whether the power socket is connected;

2, turn on the power switch, the instrument displays "723C"

3. After the instrument has undergone self-test, press the "MODE" key and then press the "2" key, the instrument displays "DATA"

2. Basic usage method of visible spectrophotometer

1. Press the "GO TO λ" key to input the set wavelength;

2, four cuvettes, where the reference sample is placed in the R position, and the remaining three are placed in the sample to be tested. Put the cuvette into the cuvette holder in the sample cell and cover the sample cell cover;

3. Push the reference sample into the light path and press the "ABS%" key to make the instrument automatically adjust zero and full scale;

4. Then push the sample to be tested into the light path to display the absorbance value of the sample;

5. If you want to print out the data of the sample to be tested, just press the "START/STOP" key.

Note the use of visible spectrophotometer:
1. After every day's use, check carefully whether there is any solution overflow in the sample room. If there is any overflow, it must be dried with filter paper at any time;

2. After using the visible spectrophotometer, cover it with a dust cover.

Ultraviolet visible spectrophotometer usage brief process
Power on: Turn on the computer and the spectrophotometer.

Open the software: directly click the icon, and then from the menu bar, file-open, find the relevant mark to open. (Another way, from my computer-UV-find the markings to open)

Click connecTIon, the machine self-test, after the self-test is over, click "OK" (If the machine is turned on before the experiment, the self-test will not appear)

Zero adjustment: first put a cuvette filled with distilled water in a channel inside (be sure to close the lid after putting it in the cuvette), and adjust the zero. Then put a cuvette filled with distilled water in the outer channel, observe the absorbance, select one, and then adjust the zero again. (Click the zero adjustment key several times to ensure zero adjustment)

Test sample: Use the selected cuvette to test, first rinse the cuvette with the sample to be measured two to three times. Then pour the sample (note that when holding the cuvette, do not touch the smooth surface, pinch the rough surface with your fingers, and try not to spill the liquid on the smooth surface. If it overflows, wipe it dry with lens cleaning paper and observe. There are no water drops and traces, and then put it into the channel. So as not to affect the absorbance.)

In the data column, type the number code in the ID column, then put the cursor on the concentration or absorbance column, click read to get the absorbance. (When testing samples, take a few more samples and make them in parallel until the result numbers are similar.) After the measurement is over, save the data and copy the data for further calculation and analysis.

Disconnect, click unconnenTIon. Turn off the spectrophotometer and computer. Turn off the power. Wash the used cuvette with distilled water and put it back in place. Clean up the experimental bench.

Adsorption experiment process: take a sample of appropriate initial concentration, add an appropriate amount of tube-shake or stir for a certain period of time-centrifugal separation-sample, dilute to 50ml-spectrophotometer detection-record data

Note:

1. When centrifugation, choose the same tube and pour the same sample.

2, the experiment process should be recorded in detail.

3, at the end of the experiment, clean and dry the used instruments and utensils.

Visible spectrophotometer and its use method and steps

3. Preparation of powder samples
  1. Choose a high-quality micro-grid (3mm in diameter), which is related to whether you can take high-quality and high-resolution electron micrographs; (Note: high-quality micro-grid is currently not prepared in our laboratory and is purchased , The price is 20 yuan/piece; ordinary carbon film copper mesh is provided for use.)

  2. Use tweezers to carefully take out the micro-grid, place the membrane face up (observe the shiny side under the light, that is, the membrane face), and gently place it flat on the white filter paper;

3. Take appropriate amount of powder and ethanol into a small beaker, and perform ultrasonic vibration for 10-30 minutes. After 3 to 5 minutes, use a glass capillary to suck up a uniform mixture of powder and ethanol, and then drop 2 to 3 drops of the mixed liquid onto the microgrid. (If the powder is black, when the surface of the white filter paper around the micro-grid becomes slightly black, it will be moderate at this time. If the powder is dripped too much, the powder will not be dispersed, which is not conducive to observation. At the same time, the probability of the powder falling into the electron microscope is greatly increased. , Seriously affect the service life of the electron microscope; if the dripping is too small, it will be unfavorable for the observation of the electron microscope, and it is difficult to find the powder particles required by the experiment. It is recommended to prepare by the teacher or prepare under the guidance of the teacher.)

4. Wait for more than 15 minutes to allow the ethanol to evaporate as much as possible; otherwise, load the sample on the sample stage and insert it into the electron microscope, which will affect the vacuum of the electron microscope.