Fig. 3: Stability of colloidal AuNPs (λmax = 528 nm) and corresponding SERS spectra in the presence of pesticides and HCl (2 M).

a UV–vis spectra of (1) Au alone, (2) pesticide alone, AuNPs in the presence of HCl (2 M) and (3) acephate (ACE), (4) carbendazim (CBM), (5) thiamethoxam (THI) and (6) tricyclazole (TRI). b SERS ‘fingerprint’ spectra for Au alone (red line), ethanol alone (blue line), pesticide alone (black line), AuNPs in the presence of HCl (2 M) and ACE (pink line), CBM (green line), THI (purple line) and TRI (dark cyan line). Pesticide alone (black line) is the Raman spectra for CBM at 100 ppm and confirms that no ‘fingerprint’ SERS spectra can be obtained unless AuNPs are present (green line).