Perplexing compound
Posted: Thu Mar 28, 2013 11:53 pm
I have been asked if I can make an LC/MS/MS method for bromoxynil, it's been around for ages but usually analyzed by other means. The problem is the target is the heptanoate and bromoxynil heptanoate (around 389 da) isn't what you see in the first quad it's bromoxynil (276 da). Why do I see the 276-80 transition elute with multiple peaks late in the gradient? I know due to stability and the ester that if you don't acidify samples it will all be bromxynil alone and elute early due to it's polarity but I don't want that. I can acidify the sample and stabilize the compound, remove the early eluting peak but can't find a decent peak that I can use to quantitate with. I want the non-polar late eluter so it's undeniably bromoxynil heptanoate and not just bromoxynil. I see some late eluting peaks but they drift and I'm not sure what I'm looking at. Nasty adsorption too, I've run into very few compounds that I've actually had carry over with and this is one of them. I'm thinking maybe pass this compound off to the GC or HPLC guys and let them extract it if they have to. Does anyone have a trick or done this and can say yeah, use this column and mobile phase and it will work beautifully? I'm currently using a 50 mm C18 and CH3CN H2O formic mobile phases.