Chromatography columns can be divided into two categories: packed columns and open tube columns. Mostly made of metal or glass. There are shapes such as straight pipe, coil pipe, U-shaped pipe, etc. Liquid chromatography usually uses packed columns.
The separation efficiency of the chromatographic column depends on the selected stationary phase, as well as the preparation and operating conditions of the chromatographic column. Chromatography is a separation and analysis method, and separation is the core. Therefore, the chromatographic column responsible for separation is the heart of the chromatographic system.
The chromatographic column consists of a column tube, a pressure cap, a sleeve (sealing ring), a sieve plate (filter), joints, screws, etc. Column tubes are often made of stainless steel. When the pressure is not higher than 70 kg/cm2, thick walled glass or quartz tubes can also be used, and the inner wall of the tube requires a high degree of smoothness.
To improve column efficiency and reduce pipe wall effect, the inner wall of stainless steel columns is often polished. Some people also apply fluoroplastic on the inner wall of stainless steel columns to improve the smoothness of the inner wall, which has the same effect as polishing.
There are also those that use molten silicon or glass lining for thin tube columns. The column joints at both ends of the chromatographic column are equipped with sieve plates made of sintered stainless steel or titanium alloy, with a pore size of 0.2-20 μ m (5-10&μ m) depending on the particle size of the packing, in order to prevent packing leakage.
Chromatography columns can be divided into two categories based on their purpose: analytical and preparative, with different size specifications
1. Conventional analysis column (constant quantity column), inner diameter 2-5mm (commonly 4.6mm, there are 4mm and 5mm in China), column length 10-30cm;
2. Narrow bore, also known as narrow bore or semi micro column, with an inner diameter of 1-2mm and a column length of 10-20cm;
3. Capillary column (also known as micro column) with an inner diameter of 0.2~0.5mm;
4. Semi prepared column, inner diameter>5mm;
5. Laboratory preparation column, inner diameter 20-40mm, column length 10-30cm;
6. The inner diameter of the production preparation column can reach several tens of centimeters. The inner diameter of the column is generally determined based on the column length, packing particle size, and equivalent flow rate, in order to avoid pipe wall effects.