ABSTRACT
A simple,rapid and sensitive upconversion immunochromatographic assay(UICA) was developed to detect imidaclothiz using NaYF4:Yb,Er upconversion nanoparticles(UCNPs) labeled with anti-imidaclothiz monoclonal antibody. The amino-modified UCNPs were conjugated with anti-imidaclothiz monoclonal antibody to prepare the UICA strip,which could realize the quantitative detection of imidaclothiz using a fluorescence photometer with an external 980 nm laser source. The working conditions of the UICA were systematically optimized, and the sensitivity, specificity, precision and accuracy were assessed by the studies of cross-reactivity (CR), spiked recovery and validation with HPLC. Under the optimal conditions (pH 8. 0, 0.3 mol/L NaCl,2.5% methanol and 0.2% PEG2000), the UICA could be completed in 25 min for the detection of imidaclothiz. The half-maximal inhibition concentration (IC50), limit of detection (IC10) and linear range (IC10-IC90) were 97.37 ng/mL,26.30 ng/mL and 26.30-363.08 ng/mL, respectively. The UICA had no CR with the analogues of imidaclothiz except for imidacloprid. The average spiked recoveries were 71.8%-97.2% with the relative standard deviations of 0.7%-10.7% in the matrices of paddy water, soil,pear,peach,wheat,cucumber,tomato and rice. The detection results of UICA for the authentic paddy water and pear samples were consistent with that of high performance liquid chromatography (HPLC).