Supporting Information of Simple and selective detection of pendimethalin herbicide in water and food samples based on the aggregation of ractopamine-dithiocarbamate functionalized gold nanoparticles   Jigneshkumar V. Rohit and Suresh Kumar Kailasa* Department of Applied Chemistry, S. V. National Institute of Technology, Surat 395007, India *Corresponding author, Phone: +91-261-2201730; Fax: +91-261-2227334 E-mail: sureshkumarchem@gmail.com; skk@ashd.svnit.ac.in (a) (b) Fig. S1 (a) Synthesis of RAC-DTC-Au NPs and (b) UV-visible absorption spectra of Au NPs upon the addition of RAC-DTC from 10 to 25 µL (1 mM).

Fig. S2 FT-IR spectra of (a) RAC, (b) RAC-DTC and (c) RAC-DTC-Au NPs. -NH and OH (b) -C-S -CS-NH -SH (c) -SH peak disappeared Fig. S2 FT-IR spectra of (a) RAC, (b) RAC-DTC and (c) RAC-DTC-Au NPs.

Fig. S3 1H NMR spectra of (a) RAC and (b) RAC-DTC. -NH -ring protons -CH2 and -CH -OH -CH3 (b) -OH -NH peak disappeared -SH -OH Fig. S3 1H NMR spectra of (a) RAC and (b) RAC-DTC.

Fig. S4 Structures of herbicides which were used in the present assaying of pendimethalin using the RAC-DTC-Au NPs as colorimetric probe.

Fig. S5 UV-visible absorption spectra of DTC-Au NPs, RAC-Au NPs, RAC-DTC-Au NPs, DTC-Au NPs with pendimethalin, RAC-Au NPs with pendimethalin and RAC-DTC-Au NPs with pendimethalin (Inset: Photograph of above solutions).

(a) (b) Fig. S6 FT-IR spectra of (a) Pendimethalin and (b) RAC-DTC-Au NPs with pendimethalin.

Fig. S7 UV-visible absorption spectra of RAC-DTC-Au NPs with various pesticides (Inset: photograph of RAC-DTC-Au NPs with (1) acephate, (2) acetamiprid, (3) buprofezin, (4) cypermethrin, (5) chlorpyrifos, (6) fenvalerate, (7) imidacloprid, (8) quinalphos, (9) carbendazim, (10) cymoxanil, (11) hexaconazole, (12) mancozeb, (13) metalaxyl, (14)propiconazole and (15) pendimethalin.

(a) (b) Fig. S8 UV-visible absorption spectra of RAC-DTC-Au NPs with (a) cations (Na+, K+, Cu2+, Zn2+, Cd2+, Fe2+, Mn2+, Mg2+, Co2+, Pb2+, Hg2+, Ni2+, Ca2+, Ba2+, Cr3+, Fe3+ and Al3+; 500 µM) and (b) anions (Cl-, I-, Br-, NO3-, CH3COO-, SO42-, S2-, Cr2O72-, 500 µM) at pH 5.0. (Inset: photograph of RAC-DTC-Au NPs with (a) cations and (b) anions).

Fig. S9 Specific the detection of pendimethalin (500 µM) in mixture of herbicides (2,4- Dichlorophenoxyacetic acid, chlorpropham, clodinafop propargyl, glyphosate, imazethapyr, isoproturon, metribuzin, metsulfuron methyl, pretilachlor, pyrithiobac sodium and sulfosulfuron, 500 µM ) using RAC-DTC-Au NPs as a probe (Inset: Photograph of (1) RAC-DTC-Au NPs, (2) RAC-DTC-Au NPs with herbicides mixture solution, (3) RAC-DTC-Au NPs with herbicides mixture solution in presence of pendimethalin and (4) RAC-DTC-Au NPs with pendimethalin).