From the Desk of
Scott Adams, Director of Product Management for GC
Not All 5-Type Phase GC Columns Are the Same
In liquid chromatography (LC), it is well known that not all C18 columns provide the same separation. This is true for C18 columns from different manufacturers as well as C18 bondings on different silicas offered by the same manufacturer.
This is also true for 5-type phase gas chromatography (GC) columns. Not all 5-type phases are the same, even those offered by the same manufacturer. Take the Rxi-5Sil MS and Rxi-5ms columns from Restek. Even though these columns are very similar and can often be interchanged in methods, they do offer slightly different selectivities. A good example of this difference in selectivity is the analysis of pesticides. Here are just a few examples that show the different, and slightly favorable, selectivity that the Rxi-5ms phase offers over the Rxi-5Sil MS phase:
- Maybe a rose is a rose is a rose, but a “5” is not a “5,” when it comes to pesticide analysis…
- Selectivity differences in arylene GC phases…pesticides and zebras.
Another example where selectivity is different among 5-type phases is the new Rxi-SVOCms column from Restek. This proprietary phase is similar to the 5-sil type phase, however it is optimized to improve the separation of critical PAH pairs in semivolatile analysis.
It is important to know that not all 5-type phase GC columns are the same. If you are using one type of 5-phase GC column and are encountering some difficult separations, it would be worth your while to investigate other 5-type phases. Our free, easy-to-use, online Pro EZGC chromatogram modeler makes it possible for you to do this in minutes directly from your desk. You may find just the right selectivity you need to get the separations you want.
Regards,
Scott Adams, Director of Product Management for GC