Gold-based lateral-flow strip for the detection of penconazole in watermelon and cucumber samples

As a typical triazole fungicide,penconazole(PEN)is widely used in agriculture but has been proven to be toxic.In this study,we designed a new hapten to prepare a highly sensitive and specific anti-PEN monoclonal antibody(mAb)and established a gold nanoparticle-based lateral-flow immunoassay(LFIA)for the detection of PEN residues in watermelon and cucumber.The 50%inhibitory concentration(IC_(50))of the mAb was 0.42 ng/mL and the LFIA strip had a visual limit of detection(vLOD)of 2.5 ng/g and a cut-off value of 10 ng/g in watermelon and cucumbers.The calculated limit of detection(LOD)of the LFIA strip was 0.36 ng/g for watermelon and 0.29 ng/g for cucumber.The LFIA strip also gave a re-covery rate of 92.5%-109.0%for watermelon samples and 92.5%-106.7%for cucumber samples.These results using the LFIA strip are highly consistent with those seen using liquid chromatography-tandem mass spectrometry.Thus our developed LFIA strip represents a potentially reliable tool for the rapid on-site screening for PEN in watermelons and cucumbers.