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4 Common Problems And Precautions In The Operation Of FTIR Spectroscopy

Technical Knowledge 2023-11-30 16:40:44
LiCAN9 Fourier transform infrared spectrometer has the characteristics of advanced infrared light source system, stable optical system, high-performance electronic system, user-friendly operating system, strong moisture-proof treatment, rich scalability and other features. It is widely used in medicine, chemical industry, universities, environmental protection In other fields, it has been well received by the majority of users. Using the LiCAN9 Fourier transform infrared spectrometer and equipped with the imported PINK ATR accessories, it can easily meet the requirements of the new pharmacopoeia.

1.Processing And Preservation Of Kbr By Tableting Method


The KBr used for tableting does not have to be spectrally pure, and analytically pure KBr is often used abroad. However, the following points must be noted:

a. Choose regular products. It doesn’t matter if they contain moisture. The key is that they are free of impurities, especially organic matter peaks. There are also SO42-, NO3-, etc. You can do an infrared test first to check the purity.


b. If the requirements are met, a large amount of KBr can be processed. First, grind it carefully with a clean agate mortar, then dry it at 120℃ for 24 hours, or burn it in a muffle furnace at 400℃ for 30 minutes, and then cool it in a special dryer.


c. Do another KBr infrared test to see the absorption. If there is no special absorption, put it in a desiccator and store it uniformly.


d. In addition, use a small weighing bottle and a special medicine spoon to take out a small portion of KBr for daily use, which should be separated from the KBr that is stored uniformly. The saved KBr should be opened as few times as possible.


e. The KBr used for infrared must be used exclusively and should not be mixed with other experimentally synthesized KBr. Medicines follow the principle of only being allowed out, not allowed in. The same is true for treated KBr to avoid contamination.


f. It is also possible to use spectrally pure ones, but the above treatment must also be carried out.


g. Broken potassium bromide single crystal flakes made into liquid have high purity. Do not throw away broken potassium bromide flakes. They can be used for tablet pressing.


2. Processing of liquid film KBr wafers


Potassium bromide single crystal salt tablets have been used for a long time and are not very transparent or uneven. There are several ways to completely solve them:


a. Can be polished with the included polishing attachment.


b. You can first polish with the finest metallographic (the lightest color, often found in physics departments) sandpaper, and then rub it with a velveteen cloth.


c. In foreign countries, a mixture of one part distilled water and five parts isopropyl alcohol is used. First, drop it on the velvet surface for polishing, and then quickly transfer it to the dry velvet surface and rub it. The effect is also very good.

Be sure to wear gloves when handling to avoid moisture erosion on your hands.


3. Operation precautions


a. Theoretically, the grinding particle size should be smaller than the wavelength of infrared light, so as to avoid dispersion spectrum. Pay attention to try not to absorb water during the grinding process, and do not exhale into the sample.


b. When placing samples for infrared testing, be careful to open and close the sample chamber lightly, and do not exhale while facing the sample chamber, so that the background can be absorbed well.


c. Scrub the salt tablets from the inside out, and do not apply too much organic solvents such as acetone.


d. The thickness of liquid samples must be controlled.


e. It is important to wash and dry hands.

4. Processing methods for some special samples


a. Some samples generated in solution, such as complexes, are difficult to extract. The solution can be added dropwise in KBr, dried and ground. If the sample is not afraid of heating, it can be heated and dried before testing. If the sample cannot be heated, wait until the solvent evaporates, then place it in a desiccator to dry naturally before measuring infrared.


b. For some water-containing samples, if calcium fluoride salt tablets are not available, KBr powder can be used to press tablets, the sample can be dropped on top, and discarded after testing.


c. KBr tablets that are usually worn out, such as half of a chip that has been broken, can be used specifically to measure water-containing samples. If the glossy surface is not good, you can use 5 parts of isopropyl alcohol and 1 part of water, drop it on the flannel cloth and use it after polishing.


d. Process the sample according to its characteristics.


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