What Are The Types Of Capillary Columns?
Capillary columns are gas chromatography with the stationary phase coating their inner surface. To test for impurities and in clinical laboratories, the capillary column is used in petroleum and pharmaceutical industries. With the column, an optimized chromatographic separation begins. Gas chromatography is very popular which came with a stationary phase being coated on its inner surface.
There are two types of capillary columns which differ depending on the way the stationary phase is added:
· Wall-coated open tubular capillary column
· Support coated open tubular capillary column
The stationary phase is coated on the walls of the capillary tubes that make up WCOT columns. On the other hand, SCOT columns are created utilizing a capillary tube with a support material-lined inner wall. This tiny layer of material has the stationary phase adsorbed onto it, making it accessible for investigation. The more effective of the two are often WCOT columns.
It's also worth mentioning a sub/type of WCOT - a fused silica open tubular (FSOT) column. In this instance, a stationary phase is chemically linked to the walls of a fused silica tube. It is made stronger by an outside polyimide coating, giving it both flexibility and strength.
How to choose a Gas chromatograph capillary column?
Learn the difference between the two most common capillary columns: capillary column and packed column and compare them conveniently. The selection of one of them is quite confusing. Make your choice based on the general considerations below:
· Sample size
There is no longer a need for big sample injections because modern detectors are highly sensitive. Capillary columns should be the first option in such circumstances. Nonetheless, Gas chromatograph can be taken into consideration if the detector sensitivity is poor because they have higher sample load capacities.
· Cost
More affordable than capillary columns are packed columns. They have greater column bleed and worse resolution efficiency than capillary columns, though.
· Resolution Strength
Better resolution, provided by capillary columns, results in the desired separation between closely spaced peaks.
· Time-saving
The number of samples that may be analyzed at once is increased thanks to the simplicity with which components can be resolved by utilising capillary columns.
· Test Polarity
Most Capillary columns are composed of glass or stainless steel. Glass columns are more suited for polar compound separations than stainless steel columns and are typically beneficial for non-polar compound separations.
Fused silica capillary column
Applications for gas chromatography have been tested with high-purity fused silica capillaries. Untreated high-purity fused silica capillary column were discovered to be the most inert of the typical glass capillary column kinds when inertness was compared. GC, or capillary gas chromatography, is a well-known and often-used separation technique that uses capillary columns. Fused silica columns are narrow-bore capillary columns having a layer of fused silica sandwiched between a polymer stationary phase coating on the inside and a polyimide coating on the outside. These columns are frequently utilized in a wide range of GC and GC-MS applications and sectors, including quality assurance and control, food testing, and pharmaceuticals.
Advantages of Fused silica capillary column
· Compared to glass columns, the walls of the open tubular columns made of fused silica are significantly thinner.
· When compared to glass columns, the FSWC are more flexible, have higher physical strength, and are less reactive.
· Because capillary tubing gives it strength, a protective polyamide coating is put on the outside of them. As a result, the columns are flexible and may be bent into coils.