The disclosure relates to a method for the removal of an agricultural chemical having a heterocyclic ring comprising 1-3 nitrogen atoms from an aqueous liquid, comprising: (a) contacting an imprinted polymer imprinted with the agricultural chemical molecule, wherein the matrix of the polymer has been prepared from one or more monomers including bilirubin or a mono-or di-ester or amide thereof, with an aqueous liquid to remove at least a portion of the agricultural chemical, and (b) separating the aqueous liquid with decreased agricultural chemical content from the polymer binding agricultural chemical, wherein the agricultural chemical having a heterocyclic ring comprising 1-3 nitrogen atoms is selected from pyrimethanil, fluopyram, pirimiphos-methyl and fluxapyroxad, and wherein the imprinted polymer is a noncovalently imprinted polymer that includes bilirubin-containing crosslinked polyacrylates and polymethacrylates, preferably the crosslinker is ethyleneglycoldimethacrylate, and wherein 1,1&rsquo-azobis (cyclohexanecarbonitrile) (ABCHC) may be used as a polymerisation initiator. For example the polymers are prepared by mixing the agricultural chemical molecule (pyrimethanil) with bilirubin ethylenedimethylacrylic acid (EDMA) and methanol, then adding 1,1&rsquo-azobis (cyclohexanecarbonitrile) (ABCHC, initiator). The mixture is then polymerized in a water bath at 65 degrees Celsius for about 24 h. The resultant polymer is ground, sieved, and particle sorted to give 30-63 micrometer particles. The target molecule is then removed by extraction with methanol.
