Nicolet nexus smart orbit spectrometer

The 6 dpf zebrafish larvae from both control and As₂O₃-exposed groups were fixed with 4% paraformaldehyde (PFA) and washed three times with phosphate-buffered saline (PBS) for 5 min each. All 180 larvae (90 = control, 90 = As₂O₃-exposed) were dried in a lyophilizer (Benchtop Freeze Dryer Labconco, Kansas City, MO, USA) at 50 °C for 12 h to remove the water content in the samples before grinding in an agate mortar and pestle to obtain zebrafish larvae powder. Larvae powder was completely mixed with dried potassium bromide (100 mg) and subjected to a pressure of 5 t in an evacuated disc for 5 min to produce a clear, transparent KBr disc with a diameter of 13 mm and a thickness of 1 mm for use in FT-IR analyses [40 (link)]. FT-IR analyses of the freeze-dried samples were performed using a Thermo Nicolet Nexus Smart Orbit spectrometer (Ramsey, NJ, USA). The spectra were recorded in the middle infrared (IR) region (500–4000 cm⁻¹, in triplicate for each sample).