stability of neonicotinoid LC-MS standards
I’ve got mixed standards of six neonicotinoid pesticides for my LC-MS analysis that have been sat in the autosampler for more than six months. I’m getting ready to do some more so I thought it was time to make up a new mixed working solution and standard curve. Blow me if the response of the new standard didn’t match the old one almost perfectly! 

This is remarkable because it shows that neonicotinoids are perfectly stable in 5% acetonitrile at 6 degrees C and in brown autosampler vials.