Selective determination of dinitolmide and toltrazuril by surface-enhanced raman spectroscopy (SERS) using AgNPs as substrate

[Display omitted] •SERS method was first applied to the determination of dinitolmide and toltrazuril.•The enhancement factors (EF) of dinitolmide and toltrazuril were 1.76 × 105 and 1.27 × 105, the sensitivity was high.•The SERS methods would be expected to realize real-time and on-site detection for the residual of veterinary drugs. Two sensitive surface-enhanced Raman spectroscopy (SERS) analytical methods for dinitolmide and toltrazuril were developed by silver nanoparticles (AgNPs). The dinitolmide and toltrazuril were determined in 0.0565 mol L−1 and 0.0847 mol L−1 NaOH solutions respectively. The enhancement factors (EF) were 1.76 × 105 for dinitolmide and 1.27 × 105 for toltrazuril. Under optimum conditions, the methods had good linear relationship in the concentration ranges of 0.30–33.30 nmol L−1 for dinitolmide (ISERS = 1522.52 c + 27,890.46, c:nmol L−1, R2 = 0.998) and 0.30–66.70 nmol L−1 for toltrazuril (ISERS = 1334.29 c + 46,347.83, c:nmol L−1, R2 = 0.999). The limits of detection (LOD) (S/N = 3) were 0.915 nmol L−1 for dinitolmide and 1.03 nmol L−1 for toltrazuril. The effects of interferences on the determinations of dinitolmide and toltrazuril were studied. These SERS methods were successfully used to measure the content of dinitolmide and toltrazuril in the duck and chicken samples. The relative standard deviation (RSD) for the detection of dinitolmide and toltrazuril samples could reach 1.45 % (n = 5). The recoveries were 95.67%–105.39% (n = 5) and 94.79%–99.44% (n = 5) for dinitolmide and toltrazuril system respectively.