Separation and analysis of large/large molecular weight materials: using field flow separation techniques

In today's analytical instruments, chromatographic techniques such as gas chromatography, liquid chromatography, ion chromatography, and capillary electrophoresis are popular. Some new test methods are taking advantage of their unique separation and analysis to seize emerging markets in analytical chemistry. . Field-Flow Fractionation (FFF) uses a separation channel box without a stationary phase packing and a hollow, separating and analyzing large/large molecular weight samples using a separation force perpendicular to the flow direction of the sample to test sample size distribution. With molecular weight distribution. Just as the liquid phase is mainly used to separate small molecules, field flow separation is mainly used to separate large molecules or particles, so it is often called "particle chromatography." Professor J. Calvin Giddings first proposed the concept in 1966, and the field flow separation technology has developed for nearly half a century. How effective is its application in China? Let us follow the reporter's lens and walk into Shanghai Jili, listening to the chromatographic experts to tell the past and present of the field flow separation technology in China.

What is "field flow separation"?

Before the story unfolds, let’s take a look at what is the sacredness of “separation of field flow”. According to General Yao, “In fact, field flow separation is also a kind of separation technology. The biggest difference between field flow separation technology and other methods is that it The separation takes place in a very thin flow channel, not in the column, and the fluid in the flow channel can be any inorganic or organic liquid, without a stationary phase, which can greatly reduce or even eliminate shear. Stress, mild separation conditions."

The different separation principle gives the field flow separation technology many advantages that other technologies do not have: no sample pretreatment, direct injection of samples; large mass and large volume dynamic field analysis; no stationary phase, mild separation conditions; The size exclusion limit reduces the unnecessary sample interaction/adsorption due to the small surface; the sample is automatically concentrated when the sample is injected. Regarding the above advantages, Mr. Yao fully recognizes: "Field flow separation technology is an ideal means for analyzing complex colloidal particles or polymer systems because of problems such as polarization concentration, pore plugging and particle agglomeration, in field flow separation technology. Can be greatly alleviated."

Although field flow separation is still a relatively young member of the chromatographic family compared to other chromatographic methods, it is currently widely used in food, polymers, nanomaterials, biopharmaceuticals, and the environment. It is understood that field flow separation technology has a high penetration rate in foreign countries, especially in Europe, such as Italy, France, Germany, etc., especially in the analysis of water environment and soil sediment analysis in rivers and lakes, it has become a common means of environmental analysis. . The extensive combination of FFF technology and ICP-MS and laser particle size analyzer has become one of the important means of elemental morphology analysis. With the increasing attention of environmental protection, food safety and other hot issues, the application of FFF will also be rapidly expanded, with instrument technology such as DLS, MALS, ICP-MS, and more in the analysis and detection of more targets.

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