1、 Precautions for colorimetric dishes
A colorimetric dish is generally a rectangular prism, with ground glass at the bottom and on both sides, and a transparent surface made of optical glass on the other two sides, which is fused together. So when using it, the following points should be noted:
1. When taking the colorimetric dish, only touch the frosted glass on both sides with your fingers to avoid contact with the optical surface. At the same time, pay attention to handling with care to prevent external forces from affecting the color dish and causing damage after stress.
2. Any solution containing substances that corrode glass (especially alkaline substances) should not be stored in a colorimetric dish for a long time.
3. Do not place the colorimetric dish on a flame or electric furnace for heating or baking in a drying oven;.
4. When the colorimetric dish is found to be contaminated, it should be cleaned with anhydrous ethanol and wiped clean in a timely manner.
5. Do not let the transparent surface of the colorimetric dish come into contact with hard or dirty objects. When filling the solution, the height should be 2/3 of the colorimetric dish. If there is any residual liquid on the optical surface, gently absorb it with filter paper first, and then wipe it with lens paper or silk.
2、 Colorimetric dish grouping test
If there is doubt about the color dish during measurement, self inspection can be carried out using the following method:
1. Users can set the wavelength selection to the actual wavelength used, inject distilled water into a set of colorimetric dishes, adjust the transmittance of one dish to 100%, and measure the transmittance of the other dishes. If the difference in transmittance is not greater than 0.5%, it can be used together.
2. Before colorimetric analysis, each colorimetric dish is filled with distilled water and compared at the colorimetric wavelength. 4-8 colorimetric dishes with an error within ± 0.001 absorbance are selected for colorimetric measurement to avoid measurement errors caused by differences in colorimetric dishes.
3. The colorimetric dish has a detection error within ± 0.001 absorbance before leaving the factory.
3、 Washing method for colorimetric dishes
With the rapid development of spectroscopic analysis instruments, some colorimetric dishes such as trace, semi trace, fluorescence, etc. continue to appear, which require higher requirements for their use, maintenance, and cleaning. Generally, it is disposable abroad, but in China, it is reused to save costs and reduce expenses. How to clean the colorimetric dish? It can only be cleaned using various reagents and methods that can dissolve and neutralize them. In principle, the structure and transparency of the colorimetric dish should not be damaged; Secondly, neutralization and dissolution methods can be used to achieve the effect of keeping the colorimetric dish clean as before. The cleanliness of the colorimetric dish in a spectrophotometer is one of the factors that affect the accuracy of the measurement. Therefore, it is necessary to pay attention to choosing the correct cleaning method. Below are several cleaning methods:
1. For example, if the test solution is acidic, wash it with a weak alkaline solution if it is not clean. If the test solution is alkaline, wash it with a weak acidic solution if it is not clean. If the test solution is organic, wash it with an organic solvent such as alcohol if it is not clean.
2. The principle of choosing a colorimetric dish washing solution is to achieve good stain removal effect, not damage the colorimetric dish, and not affect the measurement.
3. The commonly used chromic acid washing solution should not be used for washing colorimetric dishes, because colorimetric dishes with water in the solution may sometimes generate local heat, causing the bonding surface of the colorimetric dish to crack and be damaged. At the same time, the colorimetric dish washed with washing solution may still have trace amounts of chromium remaining, which can be absorbed in the ultraviolet region and therefore affect the determination of chromium and other related elements. It is generally recommended to use a mixed solution of nitric acid and hydrogen peroxide (5:1) for soaking and washing, followed by rinsing with water.
4. For colorimetric dishes that are difficult to clean by general methods, the following two methods can be adopted.
A、 First, immerse the colorimetric dish in a solution of sodium carbonate (20 g/L) containing a small amount of anionic surfactant, rinse with water, and then immerse it in a mixed solution of hydrogen peroxide and nitric acid (5:1) for half an hour.
B、 Soak in a mixed solution of hydrochloric acid, water, and methanol (1:3:4) in a fume hood for no more than 10 minutes.
C、 The colorimetric dish cannot be washed with alkaline solution, nor can it be brushed with a hard cloth or brush.
4、 The above methods are applicable to various colorimetric dishes of our company's glass powder high-temperature sintering.
5、 Black walled trace quartz colorimetric dishes should not be soaked in alcohol due to their inconsistent materials. After use, they can be immediately cleaned with cotton balls or mirror paper dipped in alcohol, dried, and stored in a clean container or box for later use.