Preparation of competitive immunochromatographic assay for detection of residual fipronil in urine and food samples

Abstract

A colloidal silver nanoparticle (AgNP)- based lateral flow immunoassay (LFIA) was developed using an anti-fipronil polyclonal antibody (fAb), and its employment for the rapid detection of residual fipronil in spiked egg, honey, tea and human urine samples was studied. The fAb was successfully immobilized on the AgNP surface by ionic interactions and characterized using the Bradford method, UV-Vis, SEM, TEM and XPS analyses. The visible detection limit and optical detection limit of the fipronil test strip were 40 and 2.0 ppb, respectively, in fipronil standard solution. This assay showed no cross-reaction with pyraclofos or ethiprole. Finally, the fipronil test strip was effectively applied for the detection of fipronil spiked into egg, honey, tea and urine samples, with optical detection limits of 4.6, 10, 4.6 and 3.0 ppb, respectively. The results demonstrated that this assay is suitable for the quantitative detection of fipronil at trace levels in agricultural, food and urine samples.