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Review of the Current Status of Chromatography Technology and Chromatography Reagents

In the field of analytical testing, the methods and applications of chromatographic analysis are becoming increasingly widespread. Today, the determination of high-quality products involves food, medicine, environmental protection, biochemistry, petrochemicals, and more. The development and changes in chromatography technology have a significant impact on chemical reagents, especially for those engaged in production, manufacturing, management, and analytical use. Understanding the development and current status of chromatography technology leads to a new understanding of chromatography reagents, which helps further improve the accuracy and reliability of analytical testing.

Due to its characteristics of speed, accuracy, and efficiency, chromatography technology is widely applied. Recent reports reflect the great achievements in chromatographic theory research and applications in China. In fields such as the pharmaceutical industry, biochemistry, petrochemicals, metallurgy, environmental protection, pesticides, and food, chromatography technology has become one of the widely used separation and analysis methods.

Chemical reagents are an important component of analytical instruments. Although used in small quantities, their role is difficult to describe in words. Like the quality of analytical instruments, they are crucial to the success of analytical results. Chromatography reagents account for a large proportion of chemical reagents and are closely related to chromatography instruments, analytical methods, and other factors. With the continuous emergence of new chromatography technologies, methods, and requirements, existing chromatography reagents are far from sufficient.

Due to developments in chromatography instruments, columns, and software, many places have adopted international standard methods, and foreign institutions are actively promoting their technologies. With strong domestic research capabilities, many scientists have developed corresponding specialized packed columns and capillary columns, as well as new types of chromatography reagents. From the perspective of chromatography technology applications, chromatography reagents have significant room for development.

Currently, the main commercial reagents used in chromatography include the following:

1. Stationary Phases for Gas Chromatography

Common fillers include supports, diatomaceous earth, porous microspheres, and molecular sieve series. The more commonly used varieties for analysis, the higher the degree of localization. There are also pre-treated acid-washed or acid-washed silanized supports and stationary phases coated with fixed liquids, such as Chromosorb, Porapak, and HayeSep series, most of which are imported. For columns with different requirements, the stationary phase should be selected with appropriate mesh sizes to achieve ideal separation and analysis purposes. With the development and changes in chromatography columns, especially the widespread use of capillary columns, the selection and use of chromatography stationary phases have correspondingly decreased. For example, domestically produced capillary electrophoresis instruments are gradually approaching international standards, achieving full automation. The development of various application kits for nucleic acid, protein, ion, and chiral drug analysis has also reduced the demand for commonly used reagents. Currently, commonly used stationary phases include methyl silicone oil, silicone OV series, polyethylene glycol series, benzenedicarboxylic acid ester series, and Carbowax series, as well as some organosilicon modified reagents and chiral stationary phases. Chromatography standards and reference materials, typically with a purity greater than 99.5%, range from single molecules to multi-component standards for petroleum, environmental protection, pesticide residues, etc. Most of these reagents are imported. Overall, foreign gas chromatography instruments tend to be more automated and computerized, while domestic instruments are more specialized and serialized, placing higher demands on reagents.

2. Liquid Chromatography Reagents

The most commonly used mobile phase reagents include methanol, acetonitrile, acetone, tetrahydrofuran, isopropanol, n-hexane, isooctane, and chloroform. Multiple technical indicators of the mobile phase, such as content, light absorption range, acidity/alkalinity, viscosity, moisture, color, fluorescence background, and LC gradient stability, affect the column's lifespan and the quality of test results. There are few new models of liquid chromatography instruments, with HPILC instruments being the main type. In recent years, the development of capillary electrophoresis has had a significant impact on ion chromatography. In fact, ion chromatography (IC) and exchange chromatography (EC) are two different analytical techniques, each with its own advantages and disadvantages, and neither can replace the other. In metal ion analysis using ion chromatography, high-purity reagents are still used in certain quantities, though their varieties, specifications, and prices vary significantly. Additionally, foreign reagent catalogs list many new ion-pair reagents for HPLC. For reagents related to HPLC, the main issue is that the demand for each variety is small, but the quality requirements are high. If imported varieties are chosen, the prices are not low.

3. Supercritical Fluid Chromatography and Supercritical Fluid Extraction Systems, Medium-Low Pressure Chromatography, and Perfusion Chromatography

These are relatively new high-performance liquid chromatography systems. SFE primarily uses CO2 as the extraction agent, but adding other organic solvents as modifiers can yield better results. Perfusion chromatography is based on the patent of perfusion fillers. This technology uses highly cross-linked polyethylenedivinylbenzene as the matrix, which, after appropriate treatment, obtains a dual-mode pore structure, giving the medium both diffusion pores and through-pores. During the separation process, the mobile phase can directly penetrate the medium particles. Based on the above perfusion chromatography fillers, using existing liquid chromatography filler surface bonding technology, bonding chromatography ligands with different functional groups can produce reverse-phase, ion exchange, hydrophobic, and affinity chromatography fillers to separate various types of samples. Looking ahead at the development of this technology, we can see that not only polyethylenedivinylbenzene can serve as a perfusion chromatography matrix, but silica gel, dextran, cellulose, and filter membranes with ultra-large pores and through-pores may also serve as separation media based on similar principles. Therefore, with the needs of biological science, bioengineering, and the pharmaceutical industry, these new types of fast chromatography fillers will undoubtedly develop further.

4. Thin-Layer Chromatography

Commonly used thin-layer chromatography materials include silica gel and fluorescent silica gel plates, microcrystalline cellulose, aluminum oxide, and polyamide. After chemical treatment, such as with NH2, AC, CM, DEAE, and other groups, they can be used for reverse-phase thin-layer chromatography.

Some reagent catalogs also list reagents related to GC and HPLC, such as pre-treatment reagents for gas chromatography; reagents for silylation, acylation, esterification, and alkylation; labeling reagents for HPI"C, such as ultraviolet, fluorescence, and chemiluminescence detection reagents, optical purity determination reagents, and reagents for instrumental analysis like NMR.

Chromatography reagents serve instrumental analysis. With the continuous development and improvement of science and technology, as well as the updating and improvement of various analytical instruments and detection methods, the demand for chromatography reagents will inevitably undergo greater changes.