How Much Do You Know About the Structure of HPLC Columns?

About the HPLC column

High performance liquid chromatography column(HPLC) is an important core component of high performance liquid chromatography. The chromatographic column is connected and analyzed by the column material, the specifications of the structural column, etc. It is suitable for biological acids/alkali, amines, antibiotics (polyether antibiotics are more common), and amino acids.

At present, it can give full play to its advantages in almost all analysis of macromolecular organics that need to be separated. The HPLC chromatographic column tube often uses a stainless steel tube whose inner wall is precisely processed and polished to obtain high column efficiency. The stainless steel tube is resistant to corrosion by solvents, water, and buffer solutions.

Before use, the chromatographic column tube is washed with chloroform, methanol, and water in sequence, and then the inner wall of the HPLC column is passivated with 50% hno3. During passivation, let hno3 stay in the chromatographic column tube for at least 10 minutes to form a passivated oxide coating on the inner wall of the column.

HPLC Columns HPLC Column

Structure of HPLC column

(1)The liquid chromatography column is composed of a column tube, pressure cap, ferrule (sealing ring), sieve plate (filter), joint, screw (head), and column packing.

Column tube: It is mostly made of stainless steel. The thick-walled glass or quartz tube can also be used if the column pressure is not higher than 70kg/cm2. It has a high degree of smoothness for the tube’s inner wall. It’s used for the packing of column packing. Made of stainless steel, the empty column is able to withstand the solvents action.

However, since chloride-containing solvents are corrosive to a certain degree, care should be taken when using them and do not store in the column for a long time to avoid corrosion. Sealing ring: The elastic ring located on the inner wall of the spiral ring of the connector, mostly made of PTFE, is used to seal the pressure cap at both ends and the outer wall of the column.

(2) HPLC Column packing:
The separation of liquid chromatography columns is carried out between the packing and the mobile phase, and the classification of the column is determined by the type of packing.

Normal phase HPLC column:
The mostly use silica gel as column packing. It can be divided into amorphous and spherical two kinds, particle size in the range of 3-10μm, according to the appearance. Another type of normal phase filler is the so-called bonded phase silica gel with functional groups such as -CN and -NH2 bonded on the surface of the silica gel.

Reversed phase HPLC column:
It is mainly a non-polar filler with silica gel as the matrix and octadecyl functional group (ODS) bonded on the surface. There are also amorphous and spherical points. Other commonly used reversed-phase fillers include bonding C8, C4, C2, phenyl, etc., and the particle size is between 3-10μm.