USEPA Method 551.1 involves the determination of the concentration of halogenated pesticides/herbicides in drinking water by liquid-liquid extraction followed by gas chromatography and is routinely used in water quality laboratory test houses.

Without proper safeguards, pesticides have the potential to seriously threaten groundwater drinking supplies. The Safe Drinking Water Act sets standards for drinking water and mandates the Environmental Protection Agency set Maximum Contamination Levels (MCLs) for a number of pesticides in public water supplies.

Method 551.1 utilises helium as the carrier gas; however, this application note evaluates the use of an on-site generated hydrogen carrier gas, Parker domnick hunter 110H-MD hydrogen generator is used for the analysis and detection of halogenated pesticides and herbicides.