The key difference between hypersil and inertsil column is that hypersil column is the trade name for BDS column whereas inertsil column is the trade name for ODS column. The ODS column is a type of reverse-phase HPLC column that contains free –OH functional groups while the BDS column is another type of reverse-phase HPLC column that has blocked –OH groups.
Reverse-phase HPLC is a chromatographic technique that uses a hydrophobic stationary phase. This stationary phase works well for the retention of most organic analytes. The mobile phase of the reverse phase HPLC is polar. There are different types of columns used for this chromatographic technique. Hypersil (or BDS) and inertsil (or ODS) are two such columns.
CONTENTS
1. Overview and Key Difference
2. What is Hypersil Column
3. What is Inertsil Column
4. Side by Side Comparison – Hypersil vs Inertsil Column HPLC in Tabular Form
5. Summary
What is Hypersil Column?
Hypersil column or BDS column is a type of reverse-phase HPLC column which has blocked –OH groups. In other words, the hydroxyl groups in this column are deactivated/not free. We also call it BDS C18 column because this column is packed with octadecasilane chains. The term BDS stands for Base Deactivated Silica; thus, we can also name these columns as endcap columns.
This column is very important in chromatography because it has its residual silanol groups deactivated by capping. Therefore, there is minimal residual silanol activity. Moreover, this column is specific for the analysis of basic compounds. Here, the bases react with the Si-OH groups in the silica packing. BDS columns are designed to reduce the peak tailing, which is a major problem in chromatography (unable to recognize a certain peak).
What is Inertsil Column?
Inertsil column or ODS column is a type of reverse-phase HPLC column which contains free –OH functional groups. We can abbreviate it as C18 column because it contains octadecasilane chains. In other words, we can fill up a C18 column with a packing of octadecysilyl groups (these are also named as ODS groups or C18 groups) that are chemically bonded to a silica gel carrier. These hypersil ODS columns are specifically important in reverse-phase chromatographic techniques. Furthermore, this type of columns has a high theoretical plate number and also show rapid equilibration. Since these columns only need a low cost to operate, they are commonly used in reverse-phase chromatography.
Figure 1: An HPLC Instrument
However, there are several drawbacks of using these ODS columns in chromatography. For example, its overall elution is too fast, so it is difficult to separate some components in a mixture, and stabilization of the column takes a comparatively long time.
When considering the chemical structure of an ODS column, it has the hydroxyl groups (-OH) attached to the surface of the silica gel carrier where it has the structure Si-OH. This structure is known as “silanol”. In the ODS column packing, the packing is done by bonding the ODS groups to the silanol through chemical reactions. These ODS groups are bulky and are not highly reactive. Therefore, a lot of unreacted silanol groups exist in this column. However, this free silanol can cause errors during the analysis, so we have to cap these groups with some other compounds such as TMS (trimethylsilyl) groups, which are not bulky but highly reactive. This process is called end-capping.
What is the Difference Between Hypersil and Inertsil Column?
Hypersil and inertsil columns are trade names, and these are important reverse-phase HPLC columns. The key difference between hypersil and inertsil column is that hypersil column is the trade name for BDS column whereas inertsil column is the trade name for ODS column. Hypersil column or BDS column is a type of reverse-phase HPLC column which has blocked –OH groups. Inertsil column or ODS column is a type of reverse-phase HPLC column which contains free –OH functional groups.
The below infographic summarizes the differences between hypersil and inertsil column in tabular form.
Summary – Hypersil vs Inertsil Column
Hypersil and inertsil columns are trade names, and these are important reverse-phase HPLC columns. The key difference between hypersil and inertsil column is that hypersil column is the trade name for BDS column whereas inertsil column is the trade name for ODS column.
Reference:
1. “High-Performance Liquid Chromatography.” Wikipedia. 30 Dec. 2020, Available here.
Image Courtesy:
1. “Agilent1200HPLC” By Kommando – Own work. Originally uploaded here (CC BY-SA 3.0) via Commons Wikimedia
