The key difference between open tubular and packed columns is that open tubular columns require a smaller amount of sample for the chromatographic processes compared to the sample size required for the packed column chromatographic process.
Gas chromatography capillary column is a common type of chromatographic process that comes with a stationary phase that is coated on the inner surface of the column. The other type of gas chromatographic process is the packed column process. It is comparatively less common because it requires a large amount of sample.
CONTENTS
1. Overview and Key Difference
2. What Open Tubular Columns
3. What are Packed Columns
4. Open Tubular vs Packed Columns in Tabular Form
5. Summary – Open Tubular vs Packed Columns
What are Open Tubular Columns?
Open tubular columns are a type of gas chromatographic columns that are also known as capillary columns. Generally, this type of column contains an internal diameter of about a few tenths of a millimeter. There are two major types of open tubular columns: wall-coated open tubular columns and support-coated open tubular columns. The former is abbreviated as WCOT, and the latter is abbreviated as SCOT.
The wall-coated columns consist of a capillary tube that has walls coated with the liquid stationary phase of the chromatographic process. On the other hand, the support-coated columns consist of an inner wall of the capillary lined with a thin layer of support material. This support material is lined onto which the stationary phase has been adsorbed. Moreover, support-coated columns are generally less efficient than wall-coated columns. However, both these types of open tubular columns are very effective in gas chromatography compared to packed columns.
What are Packed Columns?
A packed column in gas chromatography is a type of gas chromatographic process in which we use a finely divided, inert, solid support material. Usually, it is a diatomaceous earth material. This material is coated with a liquid stationary phase. Most packed columns typically have a length that varies from 1.5 to 10m in length. Besides, they have a diameter that can range from 2 to 4 m internally.
Packed columns are less common than open tubular columns because packed columns typically require a large quantity of samples compared to the open tubular columns process. Moreover, packed columns provide a comparatively lower resolution than open tubular columns because these columns have multiple pathways for the sample to pass through.
What is the Difference Between Open Tubular and Packed Columns?
The two major forms of chromatographic processes are open tubular column and packed column. The key difference between open tubular and packed columns is that open tubular columns require a smaller amount of sample for the chromatographic processes compared to the sample size required for the packed column chromatographic process. Moreover, the open tubular columns have a high resolution whereas packed columns have a low resolution. Also, the open tubular columns do not have multiple pathways, whereas the packed columns have multiple pathways. In addition to these, the open tubular columns have a low sample size whereas the packed columns have a high sample size.
Below is a summary of the difference between open tubular and packed columns in tabular form for side by side comparison.
Summary – Open Tubular vs Packed Columns
Open tubular column and packed column are important techniques in gas chromatography. In brief, the key difference between open tubular and packed columns is that open tubular columns require a smaller amount of sample for the chromatographic processes compared to the sample size required for the packed column chromatographic process.
Reference:
1. “Packed Column.” Gas Chromatography.
2. “Ontology.” Royal Society of Chemistry.
3. “Chapter 8 Methodology Open Tubular Columns.” Journal of Chromatography Library, Elsevier, 18 Mar. 2009.
Image Courtesy:
1. “Gcms schematic” By K. Murray (Kkmurray) – Own work (CC BY-SA 3.0) via Commons Wikimedia