Study On The Colloidal Gold-Based Immunoassays For The Rapid Detection Of Chloramphenicol Residues

In this paper,the rapid determination of chloramphenicol(CAP) residues was studied by colloidal gold-based test strips.The CAP competed with CAP-OVA conjugate immobilized on the strips to combine with the colloidal gold-labeled anti-CAP polyclonal antibodies(PAbs).After optimizing the various factors and conditions of the test,the competitive immunoassay of flow-through and lateral-flow colloidal gold-labeled test strips were developed for the rapid on-site detection of CAP residues.Gold chloride was reduced with sodium citrate to make 20 nm colloidal gold,which was coupled with the PAb as immuno-colloidal gold.18μg of the antibody were needed to stabilize 1mL gold sol.The nitrocellulose(NC) membrane and absorb pab with NC membrane were selected as the materials of flow-through and lateral-flow,respectively.The CAP-OVA conjugate and goat anti-rabbit IgG were dispensed onto the NC membrane as test zone and control zone with 1μg/strip and 0.3μL/strip.The space between the two zones was 3 mm.The limits of detection of flow-through and lateral-flow were 0.8μg/L and 1μg/L,respectively.The spiked and recovery experiments of pig muscle,chicken muscle,fish muscle, shrimp muscle and milk samples were conducted with the methanol as the extract solvent, and the matrix effect could be removed by dilution with PBST.The confirmation of this study was validated by enzyme-linked immunosorbent assay.The average recovery of this method was 70.1%～112.5%,and the coefficients of variation were under 10%.The results indicated that the test strips can be applied in the rapid detection of chloramphenicol residues.The interference with the detection of CAP residues caused by the structural analogue compounds was studied.When the concentration of thiamphenicol,florfenicol,ampicillin and sulfamethazine was 1000μg/L,the effect of cross-reactivity could be ignored with the exception of chloramphenicol sodium succinate,which validated the specificity of the test. Besides,the stability test indicated that the reliability of flow-through strips was good at 4℃within 6 months.The process of detection is simple,rapid and convenient,which could be finished within 15 minutes.The results can be visually read by eyes without instrumentation.The stability and simplicity make it feasible to determine the large number of animal derived food samples.The method could be used as reference for the detection of other veterinary drugs residues.