The method uses the derivatization of the propylene oxide by the inorganic bromide present in the sample to turn the PPO into organobromine compounds. You could easily look for inorganic bromide in the samples (I assume soils) without derivatization using ion chromatography. GC-MS would still require the derivatization step as inorganic bromide is not directly compatible with GC.

You should be able to replace GC/ECD by GC/MS using the same sample preparation protocol. But keep in mind that MS differentiates between Br-79 and Br-81 (about 50:50).

Mr. Krause und Herr Weiss,

I can not thank you enough for your taking the time to help me through the developing this pesticides analysis program. We have spent thousands of dollars sending out our samples for pesticides testing. As of now I am ONLY running the USP list of pesticides and they seem to separate all compounds fairly well. I just would like to know what GC column you're using. I'm using a Restek's version of a DB-5 (5% phenylated) . I am getting some co-eluting going on. We just ordered a ZB-Multiresidue-2 column and it's film thickness is thinner ((0.2uM). Thank you again. Aufweidersehen.-Paul D. Dodson

Yes, there are some compounds that co-elute. No, you don't care because you have a mass spectrometer. 5% phenyl is fine for the GC column. I assume that you are also running LC-MS/MS since you couldn't be doing the USP list without it. We run a high aqueous column (Restek Ultra Aqueous); there are several similar phases that work equally as well.

Hi Mark,

Thank you again. I was under the impression that I could Gas-Chromatograph every molecule when I asked you guys in December. Someone had mentioned that it was handy to have UPLC/MS/MS when running the USP list though. Just which OrganoChlorine and Phosphorus pesticides need to be liquid chromatographed? -Paul D. Dodson

Mark and Tobias, or any other chemist of great erudition;

In the AOAC Method 2007.01 on extracting pesticides by the Quechers technique, the last step involves evaporating the ACN extracted sample down to less than 1.0ml and diluting it up to 1.0ml with Toluene. In trying to evapoporate these samples it took hours. My question is; can I evaporate to dryness and reconstitute or should we buy a "Turbovap or N-Evap? They're expensive as hell. Thermo has a Reactivap and has extra accouetrements that you need to buy for a high price. What about a SpeedVac? Any suggestions? Thank you-Paul D. Dodson