Merits and De-merits of different Liquid Sampling accessories used in FT-IR Spectroscopy
Liquid samples constitute a large majority of samples requiring identification and characterization using FT-IR Spectroscopy. Liquid samples can be analyzed neat or by diluting in a suitable non-absorbing solvent. For a good spectrum the film thickness can range from 0.02 mm to 0.1 mm.
Unlike sampling in UV-VIS spectral range where glass or quartz is used as cell material in IR region such materials cannot be used due to strong absorption of IR energy. The samples are contained in sample handling devices made from a range of suitablewindow materials.
Sealed Window Cells
Sealed window cells are made from suitable salts into which liquids can be poured and capped. The fixed path length windows are permanently sealed.
Disadvantages
- Path length cannot be adjusted depending on solution concentration
- It is difficult to fill the sealed cell with viscous samples
- After analysis cleaning the cell is time-consuming and not easy.
Open Window plates
开窗板以合适的尺寸可用。这些可以方便用作用作液滴可以在由NaCl或K Br制成的两个板之间压制作为薄膜并置于光谱仪窗框中。也可以通过压制一次性聚乙烯板之间的液滴来分析低挥发性液体
Advantage
- Convenient to handle and clean with solvents after analysis
Disadvantages
- Film thickness cannot be controlled
Demountable cells
Demountable cells can be used like sealed cells and offer the following advantages :
- Can be dismantled for cleaning purpose
- 不同厚度的垫片可用于制备不同厚度的薄膜
- Filling the cell is convenient with the help of a syringe
Horizontal ATR accessory
水平ATR附件a versatile accessory offering spectral analysis of a large type of samples ranging from highly absorbing samples such as aqueous solutions, viscous liquids and slurries. This accessory is based on the internal reflectance of the IR beam within the sampling crystal which forms the bottom surface of the accessory
Advantages
- Simple to operate. The sample needs only to be poured into the accessory
- 适用于如上所述的所有类型的液体
- 在分析方便后，可以用合适的溶剂清洁配件
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