Research On Immunocharomatography Strips And ELISA Kits For Determination Of Cephems Multiresidues In Milk

β- lactam antibiotic is a kind of antibiotics withβ- lactam ring in chemical structure, it includes penicillins and cephalosporins. Its mechanism of action is preventing the synthesis of cell wall by means of inhabiting the activities of Sticky bacteria-GT, thus present bactericida activities. So it was widely used in veterinary medicine to prevent and treat bovine mastitis and other infectious diseases. Because of the abuse, the residues in food have caused serious hazard to people's health such as causing allergic reactions in sensitived individuals or affectting the intestinal ?ora of consumers.This research we obtained six polyclonal antibodies (PcAb) through immunizing rabbits with conjugate of cephalxin-BSA,7-ACA-BSA, cephadroxil-BSA, cefalothin-BSA, cefotaxime-BSA, ceftiofur-KLH. In which the PcAb of cephalxin-BSA is group-specific to cephems. The specificity of anti-sera was determined by indirect competitive enzyme-linked immunosorbent assay (icELISA), and the 50% inhibitions (IC50) of cephalexin and cefadroxil were obtained at 1.5 ng/mL,2.6 ng/mL, respectively. In addition, the PcAb of ceftiofur-KLH is specific to ceftiofur with IC50 is 10ng/mL, The cross-reaction rates with other cephems below 10%.In this paper, ELISA kits and ICA assays were established with the PcAb of cephalxin-BSA as the object of study. In which the detection limits of ELISA kits is between 0.5-5.6ng/mL. The detection limits to cephalxin of ICA assay is up to 10 ng/mL after optimizition of assay conditions including optimal labeled-protein, re-dispersed solution, pad-disposed solution, quantity of gold labeled PcAb, concentrition of coating antigen, etc. Recovery rates of cephalexin and cephadroxil in spiked milk samples are between71-98%.The coefficient of variations were below 11.6. ICA strip could be reserved for more than 3 months at 2-8℃. The correlation between the ICA and ELISA methods was good by detecting 40 spiked milk sample. The result indicates that ICA results were closely aligned with ELISA .To sum up, this research have successfully established ELISA and ICA assays which could realize detection of multi-residues of cephems based on obtaining PcAb with group-specific to cephems. Two assays both possess the characters such as rapid, simple, can provide technical support for high-through,on-site, multi-residues detection ofβ-lactam antibiotic.