Development and validation of an immunochromatographic assay for rapid multi-residues detection of cephems in milk.
A one-step immunochromatographic assay (ICA) was developed for the detection of seven kinds of cephems in milk. Polyclonal antibodies (PcAb) with group-specific to cephems were raised in rabbits after immunization with cephalexin-keyhole limpet hemocyanin (KLH) conjugate. The specificity of anti-sera was determined by indirect competitive enzyme-linked immunosorbent assay (icELISA), and the 50% inhibitions (IC(50)) of cephalexin and cefadroxil were obtained at 1.5 ngmL(-1); IC(50) of cefatiofur, cefapirin, cefazolin, cefalothin and cefotaxine were 4, 3.7, 3.2, 4.5 and 5 ngmL(-1), respectively. The PcAb against cephems were conjugated to colloidal gold particles as the detection reagent for ICA strips to test for cephems. This method achieved semi-quantitative detection of cephems in <5 min, with high sensitivity to cephalexin and cefadroxil (both 0.5 ngmL(-1)). At the same time, cefatiofur, cefapirin, cefazolin, cefalothin and cefotaxine were detected at <100 ngmL(-1) in spiked processed-milk samples. This method was compared with an enzyme-linked immunosorbent assay by testing 40 milk samples, and the positive samples were validated by a high-performance liquid chromatographic method, with an agreement rate of 100% for both comparisons. In conclusion, the method was rapid and accurate for the multi-residue detection of cephems in milk.
Xie
Huiling
H
School of Food Science and Technology, Jiangnan University, Wuxi, JiangSu 214000, PR China.
Ma
Wei
W
Liu
Liqiang
L
Chen
Wei
W
Peng
Chifang
C
Xu
Chuanlai
C
Wang
Libing
L
D000818:Animals; D000906:Antibodies / Q000737:chemistry / Q000276:immunology; D055910:Antibodies, Immobilized / Q000737:chemistry / Q000276:immunology; D002506:Cephalexin / Q000276:immunology; D002511:Cephalosporins / Q000032:analysis* / Q000276:immunology; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D017979:Gold Colloid / Q000138:chemical synthesis; D007118:Immunoassay / Q000379:methods*; D008892:Milk / Q000737:chemistry*; D011817:Rabbits; D012680:Sensitivity and Specificity
D000906:Antibodies; D055910:Antibodies, Immobilized; D002511:Cephalosporins; D017979:Gold Colloid; D002506:Cephalexin