Chromatography Forum

We recently purchased an Agilent Ultivo with ESI interface for analysis of the pesticides listed in USP <561>. These are primarily pyrethroids, organophosphates, and organochlorines. I expect the first two classes to respond well by ESI-MS, but not the organochlorines. Does anyone have experience measuring organochlorine pesticides (DDT, heptachlor, etc.) in food or dietary supplements using APCI or APPI? Which of these two ionization methods would be preferred?

Agilent says that only APCI, but not APPI, is available for the Ultivo. My research suggests that we would have adequate sensitivity by APCI, but we don’t want to spend the money on the APCI source and take a chance on it not working out. So, we have decided to go with GC-ECD for the organochlorines.

Also, we have realized that the dithiocarbamates are going to require a separate sample prep. Our plan is to hydrolyze these to CS2 and analyze by headspace-GC-ECD. Wish me luck!

I think that once you have purchased a triple quad, it would be fair that Agilent makes the effort to lend you an APCI probe so you can do some tests and decide if you buy it or not...

If they don't want to lend you an APCI probe, ask them to give you demo data to demonstrate whether it works or not for your method and your target compounds. They should be able to do this in their demo lab if they want a sale. Given that pesticide analysis is a very common application, they may already have comparative data available.

If Formic Acid isn't strong enough you can use Acetic Acid. Acetic Acid is used in EPA method 545 for Anatoxin and it works great for us.