Mouse anti-Mecoprop monoclonal antibody for ELISA. Mecoprop, or methylchlorophenoxypropionic acid (MCPP), is a common general use herbicide found in many household weed killers and "weed-and-feed" type lawn fertilizers. It is primarily used to control broadleaf weeds. It is often used in combination with other chemically related herbicides such as 2,4-D, dicamba, and MCPA. Mecoprop is a mixture of two stereoisomers, with the (R)-(+)-enantiomer ("Mecoprop-P", "Duplosan KV") possessing the herbicidal activity. The United States Environmental Protection Agency has classified mecoprop as toxicity class III - slightly toxic.