Development of rapid immunoassays for the detection of ractopamine in swine urine.
The monoclonal antibodies (mAbs) against ractopamine (Rac) were prepared and their properties identified by indirect competitive enzyme-linked immunoabsorbant assay (ELISA). The IC(50) of mAbs was 2.7 ng ml(-1) towards Rac or 9.3 ng ml(-1) towards Rac-glucuronides and no cross-reactivity (CR) towards other competitors except dobutamine (CR: 3.76%). Based on the mAbs, the Rac-kit (kit) and Rac-strip (strip) were developed to detect Rac residues in swine urine. The strip and kit assay could be performed within 5-10 min and 2 h, respectively, allowing the analysis of urine samples without the need for sample clean-up. The detection limits were 1 ng ml(-1) for kit and 3 ng ml(-1) with the unaided eye, and 0.2 ng ml(-1) with the Strip Reader for strip. The correlation coefficients (R(2)) were 0.988 for kit in the range 0-128.0 ng ml(-1), and 0.987 for strip in the range 0-10.8 ng ml(-1). Comparing the gas chromatography-mass spectrometry (GC-MS) with the kit or strip in swine urine spiked with Rac standards, the differences ranged from 1.4% to 4.5% for kit and 1.0% to 4.7% for strip. However, the differences were greater than 54% for the kit and 55% for the strip test for the analysis of urine from swine treated with Rac. The results obtained from GC-MS using hydrolysed urine samples were generally in good agreement with those obtained from strip or kit using non-hydrolysed urine samples.
Li
X
X
Henan Provincial Key Laboratory of Animal Immunology, Henan Academy of Agricultural Sciences, Zhengzhou 450002, PR China.
Zhang
G
G
Deng
R
R
Yang
Y
Y
Liu
Q
Q
Xiao
Z
Z
Yang
J
J
Xing
G
G
Zhao
D
D
Cai
S
S
D000318:Adrenergic beta-Agonists / Q000737:chemistry / Q000652:urine*; D000821:Animal Feed; D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D002138:Calibration; D003429:Cross Reactions; D004350:Drug Residues / Q000032:analysis / Q000592:standards; D004797:Enzyme-Linked Immunosorbent Assay / Q000295:instrumentation / Q000379:methods; D005503:Food Additives / Q000032:analysis / Q000737:chemistry; D005506:Food Contamination / Q000517:prevention & control; D057230:Limit of Detection; D008462:Meat-Packing Industry / Q000191:economics / Q000295:instrumentation / Q000379:methods*; D056687:Off-Label Use / Q000662:veterinary; D010627:Phenethylamines / Q000737:chemistry / Q000652:urine*; D011934:Reagent Strips; D015203:Reproducibility of Results; D013552:Swine / Q000652:urine*; D013997:Time Factors; D019155:Veterinary Drugs / Q000737:chemistry / Q000652:urine*
D000318:Adrenergic beta-Agonists; D000911:Antibodies, Monoclonal; D005503:Food Additives; D010627:Phenethylamines; D011934:Reagent Strips; D019155:Veterinary Drugs; C060897:ractopamine