Introduction of Sampling System for Cationic Chromatographic Columns
The cation chromatography column is a kind of high-performance liquid chromatography, which is a liquid chromatography method for analyzing anions and cations. The method has the advantages of good selectivity, sensitivity, rapidity, and simplicity, and can simultaneously measure various components.
The catalytic column injection system
There are three main types of ion chromatography injections: pneumatic, manual, and automatic injection.
First, the manual injection valve
The manual injection uses a six-way valve, which works in the same way as HPLC, but the injection volume is larger than HPLC, generally 50 μL. The sample is first filled with a metering tube in a low-pressure state, and when the valve is rotated clockwise to another position, a sample of a fixed volume stored in the metering tube is sent to the separation system.
Second, the pneumatic injection valve
The pneumatic valve is powered by certain helium or nitrogen gas pressure. After the two-way and four-way loading of the quantitative tube, sampling and injection is carried out, which effectively reduces the error caused by the different movements of the manual injection.
Third, automatic injection
The autosampler is automatically controlled by the chromatography workstation to perform a series of manipulations such as sampling, injection, and cleaning. The operator only needs to load the samples into the storage machine in sequence. The working steps of the disc-type autosampler are as follows:
(1) The motor drives the storage tray to rotate, and the sample to be analyzed is placed directly below the sampling needle.
(2) The motor rotates forward, the screw moves the slider downward, inserts the sampling needle into the sample plastic cover, the slider continues to move down, pushes the bottle cap into the bottle, and the sample flows through the pipe under the cap extrusion Sample valve quantitative tube, complete the sampling action.
(3) The injection valve is switched to complete the injection.
(4) The motor is reversed, the screw moves the slider up, and the sampling needle returns to its original position.
The automated injection can achieve a wide range of sample injections.