Analytical high performance liquid chromatograph is an instrument that we are very familiar with. Presumably friends in the laboratory are familiar with it. Today we will talk about the preparation liquid phase that is not often used, let’s learn it together.

Preparative chromatography or purification chromatography refers to the process of using chromatography to separate a certain amount of compounds with sufficient purity for subsequent experiments or processing. Preparative liquid phase is widely used in the fields of medicine, chemical industry and natural product extraction. Although the application areas are different, the general requirements of users are very similar, and they all want to isolate the final product with a purity of 95% or higher.

Process of Preparative Liquid Chromatograph

Figure 1 Schematic diagram of a preparative liquid chromatograph

The schematic diagram of the preparative liquid chromatograph is shown in Figure 1, which consists of a solvent, a pump and a mixer (here refers to a double pump), a sampler, a chromatographic column, a detector, and a chromatographic workstation. Among them, the infusion pump, chromatographic column and detector are the key components. The pump is the driving force for the movement of the mobile phase, and the detector is the eye of the chromatograph. Different detectors are selected according to different application scenarios. In order to collect the separated fractions, the preparative liquid phase is usually equipped with a fraction collector. It is collected in a test tube or centrifuge tube through a fraction collector, and can also be connected to a larger container through a pipeline. In order to make a preparative liquid chromatograph work effectively, repeatably, and even automatically, it must also be equipped with corresponding electronic devices and computers for control and data processing.

Preparative Liquid Chromatography Features

  1. Large volume injection.
  2. High flow rate.
  3. A large number of high-purity samples can be obtained.
Figure 2 Preparing the column

Main components of a preparative liquid chromatograph

Figure 3 Schematic diagram of preparative liquid chromatograph

1.Mobile phase storage tank

The mobile phase storage tank of the preparative liquid chromatograph is usually larger than that of the analytical high performance liquid chromatograph, and a filter head is added to the pipeline connected to the pump inlet to prevent the particulate matter in the solvent from entering the pump.

2. Infusion Pump

The infusion pump is one of the most important components in a preparative liquid chromatography system. Due to the packing materials (5μm, 10μm, etc.) used in preparative liquid chromatography, there is a lot of resistance, so a high pressure pump is required. Generally, 316L stainless steel, Hastelloy, and PEEK are used as wetted materials. These materials are highly resistant to chemical corrosion and can be adapted to common mobile phases in liquid chromatography.

3. Detector

Like analytical LC, preparative LC has a variety of detectors. The most commonly used are UV-visible light detectors or differential refractive index detectors.

The most widely used detectors in preparative liquid chromatography are UV-Vis detectors, which are highly sensitive to many substances, but the sample must absorb in the visible or UV region. Because the preparative liquid phase usually has a large injection volume and does not require high sensitivity, a flow cell with a small optical path is generally suitable for preparative liquid chromatography.

Figure 4 UV-Vis detector structure

In addition to UV-Vis detectors, differential refractive index detectors are widely used in preparative high performance liquid chromatographs. detector.

4. Injector

Analytical LC and small-scale preparative LC are most commonly injected using a six-port valve. Larger-scale preparative LC uses pump injection to eliminate peak tailing.

Figure 5 Six-port valve injection
Figure 6 Pump injection

If your lab is still injecting samples manually, I recommend the HT1500L autosampler to automate your HPLC process. This is an autosampler specially designed for preparative liquid phase, with all the essentials and outstanding features, it is your best choice. The injection needle enters the sample bottle at the preset height, draws the sample, fills the loop, the six-way valve switches, and the mobile phase transfers the sample to the subsequent system. Before feeding the next sample, the system will clean the needle and tubing according to the preset program. Compared with other autosamplers, the HT1500L only retains the core sampling function and is more cost-effective.

Figure 7 HT-1500L Autosampler

5. Software module

Chromatography data processing system (CDS) is a computer system used to record chromatographic signals, process data and output analysis reports. It can improve the speed of chromatographic analysis, and also create favorable conditions for chromatographic analysis workers to conduct theoretical research and develop new methods.

6. Fraction collector

When preparing in the fields of scientific research, medicine, and colleges and universities, the fraction collector can be used to automatically collect the required fractions according to various collection modes, instead of manual operation, and improve work efficiency.

“If you want to do good work, you must first sharpen your tools”, Welch Materials has always been committed to the research and development, production and sales of liquid chromatographs, helping customers to adapt to constantly updated regulatory requirements, and assisting cutting-edge scientific research and daily production analysis and preparation work .

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