1525 binary lc system

Chromatographic analysis was performed on a Waters 1525 Binary LC system (Waters, MA, USA). The analytical column was Chromolith^® RP-18C (100–4.6 μm) column (Merck, Germany); the mobile phase consisted of an isocratic elution of acetonitrile and 0.1% formic acid, at a flow rate of 1 mL min⁻¹ and detection at 254 nm. A Rheodyne injector furnished with a sample loop of 20 µL was used. The Empower 3 software was used in the for control system. Fourier-transformed infrared spectroscopy (FTIR) (Bruker Invenio-S FT-IR (Bruker Corp, MA, USA) and scanning electron microscope (SEM) (Model JEOL JSM-6460LV, Jeol Canada Inc., St-Hubert, QC, Canada) spectra were used for the characterization of the functional groups and the morphology of the LDH phase. Diamond lens attenuated total resistance (ATR) was also used.

For chromatographic separation, a Waters 1525 Binary LC system (Waters, Milford, MA, USA) equipped with a degasser, a column compartment, a manual injector, and a photo-diode array detector (PDA) was used. Empower 3 software was used for data acquisition. Separation was performed on a Chromolith^® HighResolution RP-18 endcapped (4.6 × 100 mm) column (Merck). The injection volume was 20 µL and all of the studied insecticides were detected at 254 nm. The mobile phase consisted of acetonitrile and water (26:74, v/v) at a flow rate of 0.5 mL min⁻¹. Five neonicotinoid insecticides were separated within 9 min with the elution order of thiamethoxam (t_R = 4.54 min), clothianidin (t_R = 5.30 min), imidacloprid (t_R = 5.76 min), acetamiprid (t_R = 6.45 min) and thiacloprid (t_R = 8.91 min). A centrifuge (Centurion, UK) was used to complete phase separation. An ultrasonic bath (Dksh, Hamburg, Germany) and a vortex mixer (Fisher Scientific, Waltham, MA, USA) were also used.