Introduction, ctd.
Unlike ion pairing techniques, this newapproach requires onlywater, the charge
dispersion reagent, and acetonitrile to accomplish the separation. For highest
sensitivity, wemonitored for paraquat at 257nm and for diquat at 308nm. Using the
HPLC column and these new conditions, the detection limit is 6 ppb for either
herbicide –adetectable amount of 0.12 nanograms on column. This analytical
sensitivity is enhanced five-foldwhen accompanied by a new simpleSPE sample
preparationmethod. TheSPEmethod allows sampling up to 1 liter of water, with
greater than 97% recovery efficiency for samples using reagent water.
