In this study, we prepared a monoclonal antibody (mAb) against metalaxyl
(Met) with a half-maximum inhibitory concentration (IC
50
) of 0.54 ng/mL based on a new hapten, and a gold nanoparticle-based
immunochromatographic assay (GICA) was developed for the rapid detection
of Met residues in tobacco. Under optimal conditions, even with the
naked eye, one can see the semiquantitative analysis results. The
naked eye detection limit of Met in tobacco is 25 μg/kg, and
the detection threshold is 100 μg/kg. In addition, the cross-reactivity
test shows that the mAb has good specificity for Met, and the GICA
results have a good correlation with the indirect competitive enzyme-linked
immunosorbent assay and liquid chromatography with tandem mass spectrometry
test results, which show that the method is feasible and reliable
and are more convenient and quicker than the methods using instrumentation
for detection. Therefore, GICA may provide a useful tool for the rapid
screening and detection of Met residues in tobacco.