Chromatography Forum

Well the EPA has finaly caught up with me and demanding I get MDL's in ECD ranges with my 5973 MSD!
I'm developing a sim method for the organochlorines I run thinking that this will work.
My boss wants me to shoot my 525 SPE extracts on one of our dual ECD 6890's for a 508/525 method.

Anyone else out there doing the 508/525 scheme? Any pit falls to avoid?
Any hints?
Everyone in marketing say to get a 5975 so that SIM/Scan can be done. I got a $10K quote to upgrade my instrument to SIM/Scan including the triple offset detector, but my powers that be do not want to spend any more money!

Thanks
Bear

We're running both, but went to a Thermo DSQ-2 GCMS for 525. It will be difficult at best with the 5973. Also, SIM works best on compounds with relatively simple fragmentation patterns. For instance we run SIM for PAH's routinely, and it works very well. When you move over to pesticides, a number of them will have very busy (a lot of ions) mass-spectrum. What this means is that you do not have any particular ion (or several so you have confirming ions) that are really strong to monitor. 508 with an ECD is simply going to give a lot more sensitivity when compared to a 5973 (even in SIM).

The other issue to consider is what else needs to be run on the instrument. If you're going to be running dirtier extracts and then wanting to easily switch (say going from 625 to 525) it is going to be even more of a struggle. Particularly on the 5973, if you get it to work, it will be with everything pretty much dialed in perfectly. To keep the sensitivity you need will be difficult if you're also running dirtier extracts.

If your ECD GC is going to be running PCB's on tank farm bottom sludge you're going to have the same issue, however, you're not pushing the instrument to its limitations as you would be on the 5973, so it would likely be less problematic to switch back and forth in this scenario.

Hope this helps,

Greg