Guest Author: Ramkumar Dhandapani, Ph.D.- Gas Chromatography Technical Manager
In gas chromatography (GC), the separation of analytes is achieved primarily based on boiling point (Van der Waal’s interaction), although other intermolecular interactions can give chromatographic selectivity.
Volatile and semi-volatile analytes enter a hot split/split-less inlet and vaporize in the liner. The vaporized analyte from the inlet then enters a relatively cool column head and condenses as droplets over the first few meters. As the oven temperature increases, the lowest boiling analyte, usually the diluting solvent, starts to partition. Then the mixture of analytes divides between the carrier gas and the stationary phase in the GC columns.
If the components of the stationary phase have only Van der Waal’s interaction with the analyte, then a true boiling point based on separation occurs. However, if the stationary phase and analyte has dipole- dipole interaction in addition to Van der Waal’s interaction, then the elution order cannot be judged by its boiling point. In fact, this is a great advantage in many cases. For example, if two volatile analytes have the same boiling point and are co-eluting on a low polar column, a selectivity change will be recognized with a more polar column because of other intermolecular interactions like dipole-dipole, dipole induced dipole interaction. Hence, proper classification of GC columns is key to successful column selection.
Zebron™ GC column selection is quite simple and are classified under 4 categories:
Essentials: These are well established selectivities that are essential to GC analysis.
Unlimited: These Zebron columns are proprietary phases designed for specific analyses, such as the analysis of bioethanol, blood alcohols, drug screening applications, and multiresidue pesticide analysis.
Inferno: The Inferno line of columns have an advanced polymer bonding technology and specialized high temperature polyimide coating, which provides high temperature stability. These columns are temperature stable to 400oC (isothermal) and 430oC (temperature ramp).
Plus: The Plus line of columns contain premium enhancements in terms of inertness and stability of the column.
Listed in the table below are few examples of Zebron columns and their classification:
To make column selection even easier, Phenomenex provides a GC Column selection webtool
This web tool provides 5 different ways to find the right Zebron GC column for your application (click image to start searching).
Find Zebron GC columns by:
Part number: Enter a manufacturer or supplier part number to find the Phenomenex alternative or direct equivalent GC column.
Manufacturer: To choose a column by manufacturer, select a manufacturer, then select a column from the drop-down list to find the Phenomenex alternative or direct equivalent GC column.
Phase Chemistry: Choose the phase chemistry you are looking for from the drop-down menu. For example, 624, 5, 5ms, and wax are some commonly searched phase chemistries.
Official Method: Columns can be found based on an official method recommendation. Some commonly used official methods are US EPA methods, USP, and ASTM. Choose the appropriate official method, followed by method category and method number to receive a recommended Zebron GC column.
Applications: Choose the industry type, and you will be able to browse applications and compound classes in the dropdown menu. Choosing an appropriate compound class would further provide the right GC column recommendation for your application.
You can also order your GC and HPLC columns through our 2018/19 Chromatography Product Guide
If you are not able to find the GC column you are looking for, please feel free to live chat with our technical team. Our Technical Specialists are available nearly 24/7 to help you find the right GC column and application.
Make sure to catch up on the first few articles of “Dr. Ram Speaks GC” to brush up on all things gas chromatography!