Photodegradation of Thenovel Fungicide Fluopyram in Aqueous Solution: Kinetics, Transformation

Supplementary material

Photodegradation of thenovel fungicide fluopyram in aqueous solution: Kinetics, transformation products and toxicityevolvement

Bizhang Dong, Jiye Hu[1]

Laboratory of Pesticide Residues and Environmental Toxicology, School of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing, 100083, P.R. China.

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Text S1GC-MS analysis procedure

A 2010 gas chromatograph coupled with a MS-QP 2010 E (Shimadzu, Kyoto, Japan) series mass selective detector was employed for identification of the intermediate products. Samples were separated on a 30 m × 0.25 mm, 0.25 μm, HP-5 fused silica capillary column (J & W Scientific, CA, USA). The column temperature was programmed as follows: the initial temperature was 120 °C and increased to 210 °C for 1 min at 10 °C min-1 and then 230 °C for 3 min at 2 °C min-1. Then it was increased to 290 °C at 20 °C min-1. The total run time was 26 min. Ultra high purity helium was used as carrier gas. The carrier gas was set at 1 mL min-1. Injector temperature was maintained at 260 °C, and the injection volume was 1.0 μL in the splitless mode. The interface temperature was held at 290 °C. Mass spectra were scanned from m/z 50 to 450. Electron impact ionization energy was 70 eV.

Text S2Photodegradation products identification with GC-MS

For the identification experiments, 1% acetonitrile-ultrapure water (v:v) was spiked with fluopyram at 20 mg L-1 and then it was exposed for 200 min under UV irradiation and for 720 h under simulated sunlight irradiation. The irradiated solution was concentrated 10-fold by liquid-liquid extraction method with dichloromethane. Then, dichloromethane was evaporated in a water bath at 45 ºC under nitrogen flow until total dryness. The extract was redissolved in 2 mL acetone for GC-MS analyses. Using GC-MS system, only one product (TP I) was detected under UV irradiation. The identified product was eluted after fluopyram (tR 12.1 min) and its total ion chromatogram and electron-impact (EI)mass spectra are presented in Fig. S3. From Fig. S3, it was concluded that the monoisotopic mass of TP I was 360 with the molecular ion at m/z 360. Based on the even molecular weight and intensity of the A+2 isotopic peak, it was concluded that the molecule of this compound contains two nitrogen atom and don't chlorine. The detail analysis of mass spectra was showed in Scheme S1. Since some of TPs might be decomposes in GC-MS analysis process and EI mass spectra was difficult to explain, GC-MS analysis was excluded for further studies.

Fig. S1. XPA-I photochemical reactor

Fig. S2.UV-vis absorbance spectrum of fluopyram at varying pH values.

Fig. S3.The total ion chromatogram (a) and electron-impact mass spectra (b) of TP I.

Fig. S4.TIC (a, c) and mass spectra (b, d) of LC-MS/MS of fluopyram photodegradation products under UV(a, b) irradiation for 200 min and simulated sunlight irradiation (c, d) for 720 h.

Fig. S5.MS/MS spectra of LC-MS/MS of fluopyram photodegradation products under simulated light irradiation: UV irradiation for 200 min, simulated sunlight irradiation for 720 h.

Scheme S1. Proposed fragmentation pathways for TP I with EI.

Scheme S2. Proposed fragmentation pathways for TP I with ESI.

Scheme S3. Proposed fragmentation pathways for TP II with ESI.

Scheme S4. Proposed fragmentation pathways for TP III with ESI.

Table S1 Kinetics parameters of fluopyram photodegradation

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