As I’ve been traveling around talking with environmental chemists I’ve heard them say more than once: “Why can’t there be just one GC column set that will work for a whole bunch of methods instead of having to change columns to run a variety of methods?”
Changing columns can be time-consuming and frustrating for a pesticides chemist working with GC/ECD methods, especially when there are large backlogs and deadlines to meet. Dedicated instruments are not a suitable answer since equipment utilization is so critical and some methods are not run routinely. An Environmental Innovations chemist at Restek may have a solution.
A recent discovery by one of my colleagues at Restek, Jason Thomas, answers this question. Jason surveyed how many EPA methods he could run using a single set of Rtx- CLP and Rtx-CLP2 columns on the same GC/ECD instrument. To my surprise it came out to seven EPA methods!
He gathered chromatograms for EPA methods 8081B, 8082, 8151A, 504.1, 505, 508.1 and 552.2 and found that they could all be done using a single set of application specific columns for multiple GC/ECD methods.
Here’s a summary table showing the specifics of his survey:
| EPA Method | Column Pair | Analysis Time (min.) | Coelutions | Link to Chromatogram |
|---|---|---|---|---|
| 8081B Chlorinated Pesticides |
Rtx-CLPesticides/ Rtx-CLPesticides2 |
7 / 7 | 0 /0 | GC_EV00933 |
| 8082A Aroclor PCBs |
Rtx-CLPesticides/ Rtx-CLPesticides2 |
7 / 7 | 0 / 0 | Aroclor 1221 PCBs on CLP Aroclor 1221 PCBs on CLP2 |
| 8151A Chlorinated Herbicides |
Rtx-CLPesticides/ Rtx-CLPesticides2 |
13 / 13 | 1 / 0 | GC_EV00971 |
| 504.1 EDB, DBCP, 123TCP |
Rtx-CLPesticides/ Rtx-CLPesticides2 |
9 /10 | 0 /0 | GC_EV00020 |
| 505 Organohalide Pesticides & PCBs |
Rtx-CLPesticides/ Rtx-CLPesticides2 |
18 / 18 | 1 / 1 | GC_EV01004 |
| 508.1 Pesticides & Herbicides |
Rtx-CLPesticides/ Rtx-CLPesticides2 |
23 / 24 | 2 / 2 | GC_EV01022 |
| 552.2 Haloacetic Acids |
Rtx-CLPesticides/ Rtx-CLPesticides2 |
12 / 12 | 0 /0 | GC_EV01006 |
I noticed a couple of things as I looked at the chromatograms in this table. Not only can this many EPA methods be run on this one column set, but the resolution using the GC conditions indicated minimizes the number of coelutions for each method and the run times are optimized for fast analysis.
I’m glad to say that additional information will become available soon on a new “micro site” that will contain additional data and information about this surprising discovery. Keep checking this BLOG site for more details.
I have been using the above two Restek CLP columns for over 10 years and run Produce samples on them everyday to confirm over 100 pesticides, herbicides and fungicides and some carbamates. They are great!! Thank you Restek.
Sherry T Garris
This is old news for those of us in the environmental industry. We have been running these methods here for years, although I prefer pairing the Rtx-CLP with an Rtx-1701 for greater changes in retentions. Also, you could add wastewater methods 608 and SM6640, PCB in oil EPA 600/4-81-045, and HAA by SM6251. But tell Jason to keep up the good work!
Thanks so much for your comment Travis. I am curious… are you using the same column dimensions when you are using the Rtx-CLP and Rtx-1701 to run all of the methods we mentioned, plus those you noted? I assumed you are using several different GC systems to cover all of these different methods. Thanks also for your suggestion to add the other methods for wastewater and oil. I’ll have to see if we can generate chromatograms for those also so we can add them to this microsite.