Carboxyl retained hapten of quinclorac produces highly sensitive antibody and immunochromatographic assay

In order to obtain better anti-quinclorac antibody, we synthesized three novel quinclorac haptens de novo, including a hapten (H3) retains the carboxyl. As expected, H3 immunized mice showed the best immune re-sponses and generated the anti-quinclorac monoclonal antibody (mAb 6D2F4) with the 50 % inhibition con-centration (IC50) of 1.63 ng mL-1 in indirect competitive enzyme-linked immunosorbent assay, which is improved 30-to 245-fold than the reported anti-quinclorac antibodies, and no significant cross-reactivities with the analogues of quinclorac. Then mAb 6D2F4 was employed to develop the colloidal gold immunochromato-graphic assay (GICA) for the detection of quinclorac. The limit of detection (LOD) of naked eye observation is 8 ng mL-1, while the LODs of GICA in agro-products samples also can meet the requirements regulated by China. Besides, the detection results of blind samples by GICA show high consistency with those by high performance liquid chromatography analysis.