What is the composition of the column?

Beijing Zhongyi Yusheng Technology Co., Ltd.

The column is a crucial component in chromatography, acting as a separation device filled with a stationary phase. It can be made of metal or glass and comes in various forms such as straight tubes, coils, or U-shaped structures. Widely used across different fields, the column plays a central role in the separation process. Let’s take a closer look at what it’s made of.

Column Components

Chromatography is a powerful technique for separating and analyzing mixtures. At its core, the column is responsible for this separation and is therefore considered the heart of the chromatographic system. The performance of a column is determined by its efficiency, selectivity, and speed. Commercially available columns often use various particulate fillers such as porous silica gel, silica-based bonded phases, alumina, organic polymer microspheres (including ion exchange resins), and porous carbon. These materials typically have particle sizes ranging from 3 to 10 micrometers.

The theoretical plate number of a column can reach up to 50,000 to 160,000 per meter, depending on the application. For general analysis, a column with around 5,000 plates is sufficient, while more complex separations may require up to 20,000 plates. Most columns are between 10 to 30 cm long, which is ideal for handling complex mixtures.

A typical column consists of several key parts: the column tube, pressure cap, ferrule (seal ring), sieve plate (filter), joint, and screw. The column tube is usually made of stainless steel, though thick-walled glass or quartz can also be used when the pressure is below 70 kg/cm². The inner surface of the tube must be very smooth to minimize wall effects and improve column efficiency. Some stainless steel columns are polished or coated with fluoroplastic to enhance smoothness. Thin-walled columns may use fused silica or glass linings for better performance.

At both ends of the column, sieve plates are installed—usually made of sintered stainless steel or titanium alloy with pore sizes ranging from 0.2 to 20 micrometers. These plates prevent the packing material from escaping. The size of the particles in the filler also determines the appropriate pore size of the sieve plate.

Columns can be categorized based on their application: analytical and preparative types. Analytical columns are commonly used for routine analysis and have an inner diameter of 2–5 mm (often 4.6 mm). Narrow-bore columns have smaller diameters (1–2 mm) and are used for more sensitive analyses. Capillary columns are even narrower, with diameters between 0.2–0.5 mm, and are ideal for high-resolution separations. Preparative columns are larger, with inner diameters exceeding 5 mm, and are used for large-scale sample preparation.

For more detailed information about analytical instruments or chromatography systems, feel free to contact Beijing Zhongyi Yusheng Technology Co., Ltd. We specialize in providing high-quality chromatography equipment and technical support to meet your research and industrial needs.