Xseries 2 icp ms

For determining Fe and Zn concentrations, collected seeds were dried at 70 °C in an oven for 3 days. The dried samples were then microwave-digested in a mixture of 3 mL of HNO₃ and 3 mL of H₂O₂ at temperatures up to 180 °C in TFM tubes (Microwave Closed System MAR6, CEM Co., Ltd.). After appropriate dilution, Fe and Zn concentrations in the digested solution were determined by inductively coupled plasma mass spectroscopy (ICP–MS, X series 2; Thermo Scientific).

Biofilms were weighed and then digested using 0.8 mL of nitric acid (trace metals grade; Fischer Scientific) on an SCP science Digiprep Jr at 65 °C for 45 min. After the digestion, 0.4 mL was transferred into a 15 mL falcon tube and filled with Milli-Q water to reach a final volume of 10 mL. For intracellular Fe quantification, cells were isolated from the matrix from an optimized protocol develop elsewhere^{22 (link)}. Total biofilms were recovered in 1 mL of oxalate/EDTA (0.1 M/0.05 M) and incubated at room temperature (RT) for 7 min. Samples were centrifugated at 6500 × g for 7 min. The supernatant was discarded, and cells were resuspended in 1 mL NaCl 0.5 M before being sonicated for 30 s at 30% amplitude. NaOH was added to the supernatant at a final concentration of 0.1 M and incubated for 5 min at RT. Samples were centrifugated at 6500 × g for 7 min and resuspended again in 1 mL of oxalate/EDTA (0.1 M/0.05 M) for 7 min. Samples were centrifugated like the previous steps and pellets were resuspended in diluted oxalate/EDTA solution (0.025 M/0.0125 M) for 7 min. Finally, cells were centrifugated and stored at 4 °C until analysis. Cells were digested as described above. Samples were analyzed for Fe content on an ICP-MS XSeries 2; Thermo Scientific and on an ICP-MS Agilent 7850 equipped with an autosampler SPS 4.

For adsorption kinetic experiments, Ni solution (500 µg/mL) was mixed thoroughly with the CB solution (1 mg/mL) at a v/v ratio of 1:1 for 10 minutes, 30 minutes, 1 hour, 2 hours, 1 day, 2 days and 30 days at 37°C. After centrifugation at 21,000 g for 30 minutes, the concentration of Ni in the supernatant was determined by ICP‐MS (x series 2, Thermo Scientific). The amounts of Ni adsorbed on the CBs were calculated by subtraction.
For in vivo experiments, after treatment, tissues including heart, liver, spleen, lung and kidney were digested by HNO₃ and H₂O₂ mixture (v/v ratio is 7:1) at 130°C until the mixed solutions became colourless and clear. The Ni concentration in all samples was analysed by ICP‐MS.