The adsorption of atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) or metolachlor (2-chloro-6'-ethyl-N-(2-methoxy-1-methylethyl)acet-o-toluidine) to a variety of plastics and silicone rubber was determined. Both herbicides adsorbed rapidly to silicone rubber, Nalgene 180, Tygon R-3603, and somewhat less rapidly to low-density polyethylene. Neither of the herbicides was significantly adsorbed by high-density polyethylene or acrylic plastic. Very little sorbed metolachlor or atrazine was extracted with methanol and acetone from low-density polyethylene, indicating that the compounds were tightly adsorbed. Radiolabeled atrazine residues slowly desorbed from Nalgene plastic into water with only the parent compound detectable by gas chromatography, indicating that no chemical transformation had taken place. Organic materials used in containers or equipment coming in contact with atrazine or metolachlor should be screened for their interaction with these compounds.
