Development of a colloidal gold-based lateral-flow immunoassay for the rapid detection of phenylethanolamine A in swine urine

摘要

Phenylethanolamine A (PEAA) is a newly emerged phenethanolamine member of the family of beta-adrenergic agonists illegally used as feed additives for growth promotion. In this study, a highly sensitive and specific lateral-flow immunochromatographic assay (LFIA) using a colloidal gold-labeled monoclonal antibody was developed for the rapid detection of PEAA. The assay procedure could be accomplished within 10 min, and the result of this qualitative one-step assay was evaluated visually according to whether test lines appeared or not. When applied to the swine urine samples, the half maximal inhibitory concentration (IC50), the limit of detection (LOD) and limit of quantification (LOQ) of the test strip under an optical density scanner were calculated to be 0.52 +/- 0.11 ng mL(-1), 0.188 ng mL(-1) and 0.263 ng mL(-1), respectively. The cut-off value of PEAA by the naked eye was 2.7 ng mL(-1). The specificity of the assay was evaluated by the measurement of cross-reactivity (CR) of the monoclonal antibody with PEAA, PEAA-NH2 and 11 other beta-adrenergic agonist compounds. Studies indicated that the monoclonal antibody was highly specific for PEAA and PEAA-NH2, with negligible cross-reactivity with other beta-adrenergic agonists including ractopamine (CR is 0.52%). To investigate accuracy and precision of the assay, swine urine samples were fortified with PEAA at different concentrations and analyzed by using the test strips with the scanner. Acceptable recovery rates of 92-102% and the intra- and inter-assay coefficients of variation (CV) of 8.70-17.65% were achieved. Parallel analysis of spiked swine urine samples with PEAA showed comparable results obtained from the lateral-flow test strip and LC-MS/MS. There was an acceptable correlation coefficient of 0.9789 between the two methods. Therefore, the described lateral-flow test strip could be used as a reliable, rapid and cost-effective on-site screening technique for the determination of PEAA residue in swine urine.