Check your chromatograms and see if your separations or column recommendations have changed! That change is probably for the better.
Using ProEZGC, you, can “search by phase” to see what compounds can be digitally separated on your column of choice (if your compound isn’t there, let us know!), or you can search by compound to find out what column will suit your needs. When it comes to pesticides, customers have an abundance of options from Restek, so we like to make sure our EZGC libraries are working to help you find the correct column and separation conditions for your specific application(s). Our updated compound lists were determined using your searches over the past decade. They include; chlorinated pesticides, herbicides, PCB’s, and other halogenated compounds. We know many of you may have saved your work on the ProEZGC platform over the years, and those results may have changed slightly, but with this update, we will be able to offer improved accuracy for separation predictions, which will help keep your lab running smoothly.
The Rtx-CLPesticides and CLPesticides2 are application-specific columns designed with EPA methods 8081B, 8082A, 8151A, 504.1, 515, 508.1, and 552.2 in mind. They are designed to be used side-by side, allowing for one injection to reach two detectors (Figure 1), resulting in two simultaneous separations of the same sample. ProEZGC libraries for these columns contain the compounds found in the listed methods in addition to 209 PCB congeners.
Figure 1: Flow path (red) of a single injection. The whole sample (thick arrow) passes through the guard column into the press tight Y-connector. The sample then splits (thinner arrows) between the Rtx-CLPesticides and CLPesticides2 columns, both of which are connected to ECD’s.
In the face of the ongoing helium shortage, ProEZGC is especially helpful if you, like many others, are moving away from helium as a carrier gas. Read our technical note here, for more information about changing carrier gas while using this column set.
You can also use ProEZGC to model separations on one column, then see how it affects separation on the other, simplifying troubleshooting when you need to improve your method. We offer some already-optimized methods here for seven EPA methods, but there is always the chance you need something a little different. There are lots of reasons you might need to change the method, such using a different carrier gas, sample matrix, sample clean-up, or if you just have new analytes showing up in the sample, which is why ProEZGC is there to help. Since the columns are sharing the same oven, changing the separation on one column risks changing the separation on the other, which can be a difficult balance.
So, check your chromatograms! And let us know what you think of your updated separation and column recommendations!