I'll be analyzing river water for organophosphurus pesticides (dichlorvos, diazinon, clorpirifus, parathion, metamidodos and glifosato so far), but I've been having trouble finding a methodology suitable for most of those analytes.
I did some analyses on organochlorine and acetic acid pesticides using one type of SPE cartridge Strata X Reversed Phased by Phenomenex. I found them useful, just needed to spend some time on method development. You can contact Phenomenex and they can send you free samples.