Rapid Determination of Diazepam Residue in Aquatic Products by Immunomagnetic Beads-Colloidal Gold Immunochromatography Assay

Aiming at the problem of diazepam residues in aquatic products,a rapid and sensitive detection method of immunomagnetic beads-colloidal gold immunochromatography assay was set up. The immunomagnetic beads prepared by coupling streptavidin magnetic beads with biotinylated diazepam monoclonal antibody were used to rapidly enrich and separate the residues of diazepam in aquatic products,and the colloidal gold immunochromatography assay was used for semi-quantitative detection. The optimized results showed that concentration of colloidal gold labelled antibody,antigen(T-line)and sheep anti-mouse IgG(C-line)were 25 μg/mL,0.6 and 1.5 mg/mL,respectively. The spraying quantity of colloidal gold labelled antibody was 3.0 μL/cm. When diazepam was spiked at the concentration of 1.0,5.0,10.0 and 15.0 μg/kg,the recovery range was from 78.34% to 90.40%,and RSD was from 5.03% to 8.96%. This method had strong specificity and good stability,and the detection could be finished within 25 min. The limit of detection of diazepam residues in aquatic products was 0.5 μg/kg,which was better than the conventional pretreatment method. Furthermore,40 samples were analyzed and the results were consistent with those obtained in GC-MS. It showed that the immunomagnetic beads-colloidal gold immunochromatography assay could be used as an effective method for the rapid determination of diazepam residues in aquatic products.