Development of a GNP-based lateral flow immunoassay for the detection of isoprothiolane in rice samples

Isoprothiolane (IPT) is widely used to control rice blast, but can cause unacceptable harm to organisms making its detection in rice crucial. In this work, a hapten based on the structure of IPT was produced to prepare a monoclonal antibody (mAb) with high sensitivity and specificity. The half maximum inhibitory concentration of the anti-IPT mAb was 0.81 ng/mL as determined by ELISA, and the cross reactivity with analogues was negligible. A GNP-based lateral flow immunoassay (LFIA) method was subsequently developed to quantitatively detect IPT in brown and polished rice. The optimized LFIA, in brown rice samples, showed a visual limit of detection, cut-off value and calculated limit of detection of 2 mg/kg, 10 mg/kg and 81 ug/kg, respectively and 0.2 mg/kg, 4 mg/kg and 66 ug/kg in polished rice samples. Recovery rates in spiked brown and polished rice were 95.21 %-103.06 % and 91.05 %-104.13 %, with a coefficient of variation of 1.25 %-4.17 % and 2.93 %-8.42 %, respectively. No significant difference in recovery rates were seen between LFIA and LC-MS/MS indicating that the prepared GNP-based LFIA had good potential for the detection of IPT in rice.