Packed Columns Supports
Supports hold stationary phases, and ideal supports are said to have no direct contribution to separations of samples. However, peak tailing and component decomposition sometimes occur due to the characteristics of a support. It is therefore necessary to choose an appropriate packing material for each analytical purpose.
The capabilities required of supports are shown below:
- Must be able to retain stationary phases in a stable manner.
- Must have a structure with an appropriate surface area in order to contribute to good separations.
- The surface of the support should be inert physically and chemically in order to prevent adsorption of samples.
- Must possess excellent mechanical strength and good permeability with respect to carrier gases.
- Must possess excellent heat resistance.
In general, diatomaceous earth is used for GC supports. Diatomaceous earth supports can be divided into two main types consisting of brown and white supports.
In comparison with white supports, brown supports possess large surface areas and can be coated with a wide range of stationary phases from low to high concentrations. White supports possess low surface activities, so even at low stationary phase concentrations, high sensitivity analyses free from adsorption and decomposition are possible.
Other supports including terephthalic acid and fluoride supports, etc. are also used according to analytical requirements.
- Diatomaceous earth (brown, white)
- Fluoride beads
- Glass beads
- Terephthalic acid beads
- Porous polymer beads, carbon
- Adsorbents (alumina, activated carbon, and other GSC supports)
As diatomaceous earths possess metal oxides and silanol groups on their surfaces, adsorption and decomposoition of samples are caused by interactions between samples and diatomaceous earth surfaces. To remove metal oxides, diatomaceous earths are treated with acids or bases. In addition, in order to deactivate silanol groups, silanization reagents are used to cap these groups.
|NAW||Non acid washed|
|AW||Acid washed (neutral pH)|
|BT||Base treated (alkaline pH)|
|BW||Base washed (neutral pH)|
|AW-BT||Acid washed and base treated (alkaline)|
|AW-BW||Acid and base washed (neutral)|
|AW-DMCS||Acid washed and DMCS treated (neutral)|
|Shimalite®||Brown diatomaceous earth support for medium to high stationary phase concentrations|
|Shimalite® W||White diatomaceous support for low stationary phase concentrations|
|SHINCARBON A||High purity carbon support|
|Sunpak-A||Porous polymer beads|
|Shimalite® TPA||Terephthalic acid support for analyses of samples containing water|
|Shimalite® F||Fluororesin support|
|Shimalite® Q||Crystal support|
Shimalite® products are original brown colored supports which are manufactured from high purity diatomaceous earth. Shimalite® supports can be used for a wide range of analyses covering low to high boiling point samples, and are capable of supporting medium to high stationary phase concentrations (5-30%).
Shimalite® W supports are suitable for analyses of biochemical and pharmaceutical samples (steroids, alkaloids, carbohydrates, amino acids, and agricultural chemicals).
The surface activity of Shimalite W is extremely small, with the result that adsorption of samples on these supports is almost nonexistent even at low stationary phase concentrations (e.g., approximately 0.1%). These supports are suitable for rapid analyses of trace amounts of high boiling point and active substances.
suitable for analyses of biochemical and pharmaceutical samples (steroids, alkaroids, carbohydrates, amino acid and agricultural chemicals) .
Physical and chemical characteristics of Shimalite® W
*Physical and chemical characteristics of Chromosorb® W are also shown for comparison.
|Shimalite® W||Chromosorb® W1)|
|Free Fall Density(g/cc)||0.23||0.18|
1) Values for Chromosorb® W were reprinted from Technical Bulletin No. FF101D published by Johns-Manville.
Shimalite® TPA supports are terephthalic acid supports which can be used for analyses of samples containing water. Shimalite TPA is suitable for analyses of aqueous solutions of aldehydes, fatty acids, and alcohols containing 7 or less carbon atoms. They can also be used for analyses of samples such as sulfur compounds, which are strongly adsorbed by other types of supports.
Shimalite®F is a Teflon (tetrafluoroethylene polymer) support. Together with the carbon support SHINCARBON A, Shimalite TPA has a very small surface activity and can be used for analyses of easily adsorbed substances such as water.
Shimalite®Q supports consist of crystal particles with extremely low levels of absorption activity. They are also used in resistance tubes for reference columns.
SHINCARBON A is a highly purified carbon support for GC manufactured by firing a synthetic polymer, which is then highly deactivated. This product is highly heat and water resistant. It can be used for analyses of aqueous solutions containing substances with low to high boiling points, and trace amounts of polar substances in air, which cannot be analyzed using diatomaceous earth, terephthalic acid, or teflon supports.
- This carbon support is highly deactivated, and is extremely stable both physically and chemically. Polar compounds such as alcohols and fatty acids are not adsorbed on its surface. In addition, as it does not undergo hydrolysis, it is suitable for analyses of water soluble compounds.
- SHINCARBON A's stationary phase retention and separation capabilities are comparable with diatomaceous earth supports.
- As it consists of 100% carbon, it can be used at high temperatures under inert gas atmospheres.
- As this material is a vitreous carbon, it possesses high mechanical strength and does not generate fine particles. This results in high carrier gas permeabilities, lower column pressures, and improved separation efficiencies.
- As this is a chemically synthesized product rather than a natural product like diatomaceous earth, there are no deviations between lots.
Sunpak-A consists of highly crosslinked, high-performance porous polymer beads developed using our company's original technology. In addition, Sunpak-A can be coated with stationary phases thus enabling analyses of samples which would normally be difficult using conventional diatomaceous earth supports due to decomposition and adsorption phenomena.
- This product can be used for analyses including aqueous solutions of short-chain hydrocarbons (C1 – C3), aqueous solutions of short-chain alcohols (C2 – C7), and CO2.
- This product also provides superior results in microanalyses of organic solvents.
Shimalite®-Ni [reductive catalyst]
- This product consists of diatomaceous earth particles coated with thin layers of metallic nickel, and is designed to serve as a reductive catalyst.
- ShimaliteR-Ni is effective as a reducing agent designed to convert materials which cannot be detected in hydrogen flame ionization detectors (FIDs), such as carbon dioxide (CO2) and carbon monoxide (CO), into methane (CH4), which can be detected.
(Catalyst designed for high sensitivity analyses (ppm level) of carbon monoxide, carbon dioxide, and formaldehyde, etc. through conversion to methane.)