Pre Column and Guard Column

Guard Column and Pre Column (Online Filter) are things that everyone often uses in daily experiments, but many will have doubts, they look too similar, aren’t they the same thing? What’s the difference? This article will tell you in detail.

Differences between Guard Column and Pre Column

Both are connected in front of the chromatographic column, and both can prevent solid impurities from clogging the chromatographic column frit. But there are also differences between the two. The Pre Column is a sieve plate, which can only filter out some impurities larger than the aperture of the sieve plate. When cleaning, just remove the sieve plate, ultrasonicate with water and methanol for 10 minutes each, and it can be used normally.

Guard Column is placed in the sleeve of the guard cartridge. The guard cartridge can be replaced. There are packings in the cartridge, which can not only filter solid impurities, but also absorb some weak polar or non-polar organic pollutants, preventing the chromatographic column. The contamination of the inner packing can fully protect the chromatographic column.

How do we select Guard Column?

How to choose a Guard Column without affecting the separation analysis? First, choose a Guard Column that matches the column packing specifications. For most analysts, a 1cm long Guard Column will provide adequate protection. Of course, the longer the Guard Column is, the more filler there is in it, and the more protective it can be, but the retention time of the sample will also increase accordingly. The principle for selecting a Guard Column is: under the premise of meeting the requirements of separation and analysis, choose a short Guard Column as much as possible, and choose a packing with less retention for the separation sample as much as possible.

There are two main types of Guard Columns, direct-connected or free-standing. The direct-connect structure is directly installed on the chromatographic column by the chromatographic column manufacturer, and must be ordered together with the chromatographic column. It can be used very conveniently, but cannot be modified. The stand-alone structure can be installed and connected by chromatographers at any time, and can be connected to any brand of chromatographic column, and the appropriate Guard Column length and column packing can be selected according to different samples. In addition, from the perspective of the Guard Column structure, the Guard Column structure is divided into whether the Guard Column core can be replaced. Now most of the Guard Columns can be replaced, which can reduce the use cost of the Guard Column.

Welch Materials has a rich product line of online filters and Guard Columns.

If you have any problem or require further information, please contact info@welchmat

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