Original title: What are the guard column and online filter of liquid chromatography? How to use it? In the previous video of ChromClass, we mentioned the protective column and online filter of liquid chromatography. At that time, some students were very confused. They look like the same thing, aren't they? What's the difference? Today we will tell you in detail. Guard post The guard column of liquid chromatography, as its name implies, is used to filter the impurities in the sample and mobile phase,thin film distillation, protect the chromatographic column and prolong the service life of the chromatographic column. It is usually installed behind the injector and at the front of the chromatographic column. There are two types of protective columns: One is the freestanding ferrule protection column. The clamping sleeve is internally provided with a column core, the column core is internally provided with a filler and can be replaced, and the column core is selected according to the type of the chromatographic column. Expand the full text The other is the integrated ferrule protection column. This is a special chromatographic column structure,wiped film distillation, the front end of the chromatographic column is integrated, and the protective column ferrule can be opened directly. This type of guard column results in a smaller dead volume, but the cost of choosing an analytical column is higher than that of a conventional analytical column. It is worth noting that the column core of the guard column has no direction when it is used for the first time, but it has a direction after the first use, and it can not be used in another direction. In-line filter The in-line filter is used to filter the impurities and solid particles in the mobile phase and to protect the liquid phase system. It is usually installed at the back end of the pump and at the front end of the autosampler. Although it is also a ferrule type, nutsche filter dryer ,hemp extraction centrifuge, its filter element is only a sieve plate, regardless of the type of chromatographic column. In actual use, because the installation position of the online filter and the filter element are only a sieve plate, it can only be used to filter impurities in the mobile phase. The guard column has the same packing as the analytical column, so it can not only filter the impurities in the mobile phase and sample, but also intercept some strong retention, strong acid and strong alkaline substances in the sample to prevent them from polluting and damaging the packing in the chromatographic column. In addition, the guard column and the in-line filter are installed to reduce the maintenance cost of the instrument. Therefore, when the system has problems such as high pressure, impurity peak, chromatographic peak tailing, or separation effect of the chromatographic column, it is recommended to directly replace the protective column or the sieve plate of the online filter. Now you know the difference between a guard post and an in-line filter! Welcome to continue to pay attention to ChromClass, and we will see you next time! Animation: Small Bath Towel Not to be reproduced without authorization, if you need to contact toot toot: maoliandudududu In terms of separation scale, what categories can liquid chromatography be divided into? What are the different types of column sizes, flow rates,wiped film evaporator, and applications? Do you know what your liquid chromatograph has in common with a flush toilet? Right, they often block ~ so often have a classmate to ask us: Liquid chromatography is blocked again, how to do? How to find out where the traffic jam is? Let's talk about what to do if the liquid chromatography is blocked in this issue of micro-Q A of Chromatography School? Return to Sohu to see more Responsible Editor:. toptiontech.com