Selective detection of tricyclazole by optical technique using thiomalic acid–modified Au and Ag nanoparticle mixtures

This study proposes the use of thiomalic acid–modified Au and Ag nanoparticle mixtures (TMA-Au/AgNP mixes) for the selective detection of tricyclazole. Upon the addition of tricyclazole, the color of TMA-Au/AgNP mixes solution changes from orange-red to lavender (red-shift). According to the density-functional theory calculations, tricyclazole-induced aggregation of TMA-Au/AgNP mixes through electron donor–acceptor interactions was proved. The sensitivity and selectivity of the proposed method are affected by the amount of TMA, volume ratio of TMA-AuNPs to TMA-AgNPs, pH value, and buffer concentration. The ratio of absorbance (A(654)/A(520)) of TMA-Au/AgNP mixes solution is proportional to the concentration of tricyclazole over the range 0.1–0.5 ppm with a linear correlation (R(2) = 0.948). Moreover, the limit of detection was estimated at 0.028 ppm. The practicality of TMA-Au/AgNP mixes was validated for the determination of tricyclazole concentration in real samples (spiked recovery was 97.5%–105.2%), demonstrating its advantages of simplicity, selectivity, and sensitivity.