The column consists of a column tube, a pressure cap, a ferrule (seal ring), a sieve plate (filter), a joint, a screw, and the like. The column tube is mostly made of stainless steel. When the pressure is not higher than 70 kg/cm2, thick-walled glass or quartz tube can also be used. The inner wall of the tube requires a high degree of smoothness. Chromatography is a separation analysis method, separation is the core, so the separation column is the heart of the chromatographic system. The requirements for the column are high column efficiency, good selectivity, and fast analysis speed.
How to use liquid chromatography column? Wuhan Hengxin Century Technology Co., Ltd. recommends that the column should be tested for performance before use, and the results will be saved as a reference for future evaluation of column performance changes. However, it should be noted that the column performance may vary depending on the conditions of the sample, mobile phase, column temperature, etc.; in addition, the column performance test is performed according to the conditions in the column factory report (factory test) The conditions are the best conditions), and only then, the measured results are comparable.
1. Pretreatment of the sample:
a. It is best to use a mobile phase to dissolve the sample.
b. Use a pretreatment column to remove strong polarities in the sample or to produce irreversible adsorption impurities with the column packing.
c. The particulate impurities were removed by filtration using a 0.45 μm filter membrane.
2. Preparation of mobile phase:
Liquid chromatography is the separation of sample components between the column packing and the mobile phase for mass exchange. Therefore, the mobile phase is required to have the following characteristics:
a, the flow relative sample has a certain solubility, to ensure that the sample components will not precipitate in the column (or remain in the column for a long time).
b. The mobile phase is inert and does not react chemically with the sample (except in special cases).
c. The viscosity of the mobile phase should be as small as possible so that a good separation effect can be obtained when using a longer analytical column; at the same time, the column pressure drop is reduced and the life of the liquid pump is prolonged (the temperature can be lowered to reduce the viscosity of the mobile phase). ).
d. The physical and chemical properties of the mobile phase should be compatible with the detector used. If a UV detector is used, it is best to use a solvent with a lower UV absorption.
e, the boiling point of the mobile phase should not be too low, otherwise it will easily generate bubbles, which will make the experiment impossible.
f. After the mobile phase is prepared, it must be degassed. Removal of trace gases dissolved in the mobile phase facilitates both detection and prevention of trace oxygen in the mobile phase from interacting with the sample.
3. Selection of mobile phase flow rate:
Since the column efficiency is a function of the linear flow rate of the mobile phase in the column, different column rates can be obtained using different flow rates. For the best column performance for a particular column, it is best to use the optimum flow rate. For a column with an inner diameter of 4.6 mm, the flow rate is generally selected to be 1 ml/min, and for a column having an inner diameter of 4.0 mm, a flow rate of 0.8 ml/min is preferred.
When the optimum flow rate is selected, the analysis time may be extended. A method of changing the washing strength of the mobile phase can be employed to shorten the analysis time (for example, when using a reverse phase column, the content of methanol or acetonitrile can be appropriately increased).
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