Study On Application Of Gold Immuno-chromatographic Assay For Rapid Test Of Carbofuran Residue

For the purpose of conducting gold immuno-chromatographic assay (GICA) in rapid detection of pesticide residue, we chose carbofuran as a study object to establish GICA strip in which the carbofuran and carbofuran-ovalbumin (OVA) conjugate immobilized on the strips competes with the colloidal gold-labeled anti-carbofuran antibodies for rapid detection of carbofuran residue.Different size of the colloidal gold particle was prepared by reducing the gold chloride with sodium citrate heated by microwave oven. The colloidal gold particle of about 17.5 nm was suitable for labeling to an anti-carbofuran polyclonal antibody. The optimum pH for labeling was between 7.5-8.0, and the optimum spiking rate of polyclonal antibody was 12μg/ml. The absorb pad, sample pad, glass fiber of ARIST and nitrocellulose (NC) membrane HF24004 of Millipore were chosen as GICA materials. The carbofuran-OVA conjugate 0.97mg/ml and sheep anti-rabbit IgG 0.48 mg/ml was dispensed with Nano-Plotter (NP 1.2) onto the NC membrane to serve as test line and control line, respectively. The colloidal gold-labeled anti-carbofuran antibody was dispensed on the glass fiber with 20μl/unit. The NC membrane on which the carbofuran-OVA and the sheep anti-rabbit IgG were coated, the glass fiber on which the gold-labeled anti-carbofuran antibody were immobilized, the absorbent pad and sample pad were pasted in turn onto a PVC pad. The whole assembled plate was cut lengthways into strips (3 × 60mm).During detection, the strips were dipped into the sample solution for 20-30s to allow the sample to migrate upward. Then strips were taken out and placed flatted. After 10 min, the testing result was judged. This method has a sensitivity of 0.5μg/ml, without cross-reaction with the five analogs of carbofuran in the range of the test concentration. Well stabilization provided the sufficient shelf life. The test strip was...