Determination of 2,4‐D in foods by enzyme‐linked immunosorbent assay

Abstract
Antibodies raised in rabbits to 2,4‐D coupled to human serum albumin were used to develop an enzyme‐linked immunosorbent assay (ELISA) for residues in foods. The ELISA was capable of quantitating 2,4‐D at concentrations in the range 0·08–2·70 ng/ml and was highly specific for 2,4‐D and its esters. It did not cross‐react with 2,4,5‐T, but did respond to 25‐fold higher concentrations of MCPA. Samples were extracted with acidic methanol and required an acid‐base partitioning step to remove interfering co‐extractives and enable the determination of 54–216 ng/g 2,4‐D in corn, strawberry and cereals, and of 0·5–2 ng/g in apple and orange.