Chromatography Forum

I am running pyrethroids by GC-EI-MRM and I am having a very hard time finding a suitable internal standard. I am currently using a polybrominated biphenyl and that simply isn't good enough.

I have a pretty standard pyrethroid list (allethrin, prallethrin, resmethrin bifenthrin, danitol, cyhalothin, permethrin, cyfluthrin, cypermethrin, fenvalerate/esfenvalerate, fluvalinate, deltamethrin), however, not all of these compounds are found in dueterated forms. I am already using d5-bifenthrin and d5-fenvalerate/esfenvalerate as recovery surrogates. I tried d5-cypermethrin, but it produced the exact same transitions as the non-deuterated version.

I am thinking of trying permethrin next, but am concerned I will have the same problem as cypermethrin.

What is everyone else using as an ITSD? Any ideas?

Thanks

When I was working on a list like this I was just using the same deuterated PAH internal standards used in EPA8270. The were easy to set up because it is one of the first things people were doing by MRM and there are a lot of references to the transitions used already.

https://assets.thermofisher.com/TFS-Ass ... amples.pdf

This application used the same internal standards looking for PAH and PCB and Pesticides.

Thank you for the reply.

Those compounds do work pretty well with MRM, but I run into problems in dirty environmental matrices, storm water runoff and sediments. I get a huge matrix enhancement with the target pyrethroids but the deuterated PAHs do not compensate for that.

I've started using d10-Malathion as an ITSD. It's not perfect but it behaves similarly in the inlet when matrix is present, and ionizes well in the MRM collision cell.