Preparation of polyclonal antibodies to a derivative of 1-aminohydantoin (AHD) and development of an indirect competitive ELISA for the detection of nitrofurantoin residue in water.

Nitrofurans are used widely to treat animal diseases and were identified as the major compounds in many worldwide drug residue violations. To develop a rapid and convenient detection method to measure the residue of nitrofurantoin, we designed an immunogen and prepared a polyclonal antibody to develop an immunoassay in this study. The antibodies obtained were characterized by an indirect cELISA method and showed excellent specificity and sensitivity with IC50 of 3.2 ppb and no cross-reaction with most related species and compounds. Considering that nitrofurans often are used illegally to feed animals through drinking water, we measured the residue of nitrofurantoin in water spiked by the drug. The recovery rates are in the ranges of 88-103% for interassay and 90-103% for intra-assay. The CVs are in the ranges of 3.1-11.4% for interassay and 2.7-6.2% for intra-assay. The detection limit was determined to be 0.2 ppb. The immunoassay developed in this study is suitable to be used as a screening method to detect residues of nitrofurantoin in drinking water for animals.