Nexion 2000

For metal content assessment, neutrophils were plated at approximately 250,000 cells/well in 6 well plates and were subsequently stimulated with contrast agents as described. Following incubation, wells were gently rinsed with PBS 3 times to remove free Gd-DTPA or NPs. After washing, the remaining neutrophils were digested with 0.5 mL of HCl trace metal grade. The resultant solution was run under EPA Method 200.8 Revision 5.4 on a PerkinElmer NexION 2000 ICP-mass spectrometer. All samples were preserved to pH ≤ 2 before analysis.

The contents of As, Hg, Pb, and Cd in the CP samples were measured using ICP-MS (NexION 2000, PerkinElmer, Norwalk, CT, USA). In brief, each powdered sample (0.1 g) was directly weighed into teflon digestion vessels and then added to 2 mL of HNO₃. After 20 min of pre-digestion, the closed vessel was digested in a microwave digestion system (Ethos Touch Control, Milestone Ltd., Bergamo, Italy) [34 (link)]. The digestion program was as follows: (1) 600 W at 160 °C for 5 min, (2) 800 W at 210 °C for 3 min, and (3) 600 W at 210 °C for 15 min. After the digestion was finished, the sample was transferred to a 25 mL volumetric flask. Then, the digestion tank was washed with ultrapure water three times and transferred to the volumetric flask, adding ultrapure water to dilute to 25 mL. The blank control solution was prepared in the same way. The sample solution was filtered through a 0.45 μm syringe filter. An appropriate dilution was performed in the final solution of 2% (v/v) HNO₃ prior to analysis [35 (link)]. The standard solutions of As, Hg, Pb, and Cd were diluted to a series of concentrations by 2% (v/v) HNO_3. All samples were analyzed in triplicate and quantified by the calibration curves.

Sample preparation was as described previously (Danku et al., 2013 ). Dried plant material was digested with 1 ml concentrated nitric acid (trace metal grade, Fisher Chemicals) spiked with Indium (internal standard) in dry block heaters (SCP Science; QMX Laboratories, Dunmow, UK) at 115°C for 4 h. Samples were then diluted to 10 ml with Milli‐Q Direct water (18.2 MΩ cm; Merck Millipore) and analysed using ICP‐MS (NexION 2000; PerkinElmer, Waltham, MA, USA) in the collision mode (He). Reference material (pooled samples) was run to correct for variation within ICP‐MS analysis run. Calibration standards were prepared from single element standards solutions (Inorganic Ventures; Essex Scientific Laboratory Supplies Ltd, Essex, UK). The final element concentrations were obtained by normalising concentrations to sample dry weight.

The Cr(VI) removal efficiencies of cationised cellulose were determined by batch experiments at pH 4. To determine the optimal adsorbent mass for experiments, varying masses of CH-cellulose and GT-cellulose (3 – 120 mg) were added into 50 mL polypropylene tubes containing 20 mL Cr(VI) solutions (0.381 mg L
^-1), and the tubes shaken on a horizontal rotary shaker at ambient temperature (21 ± 2 °C) for 24 hours. Adsorption kinetics were determined by monitoring Cr(VI) uptake from solutions at various time points (5 – 240 minutes), while isotherms were determined after exposing adsorbents to Cr(VI) solutions of concentrations ranging from 0.06 – 0.29 mg L
^-1. At the end of reactions, adsorbents were separated from solutions by centrifugation and the supernatants filtered through 0.22 µm poly(vinylidene difluoride) (PVDF) syringe filters. The filtrates were then acidified using 5 % HNO
₃ and stored at 4 °C before analysis by inductively coupled plasma-mass spectroscopy (ICP-MS, Nexion 2000, Perkin Elmer, South Africa).
Cr(IV) equilibrium adsorption efficiencies of the adsorbents (
q_e (mg g
⁻¹) were then calculated using
Equation 5:
$q_e=\frac{C_o-C_e}{m}\times V(5)$
Where,
C₀ and
Ce are the initial and final concentration of Cr(VI) in solution (mg L
⁻¹), respectively,
V is the volume of the solution (L) and
m is the weight of the adsorbent (g).

Metal ion levels in myocardial tissues were detected as before^{79 (link)}. In short, first, we weighed approximately 0.1 g of cardiac tissue taken from the entire left ventricle below the ligature suture plane and placed it in a 15 ml centrifuge tube. Add 1.2 ml of 68% HNO3 and heated at 280 °C for 120 min. Then, add 400 μl of 30% H2O2 and digested the tissue until it becomes clear and transparent. Levels of major physiological metal ions were measured by Inductively Coupled Plasma – Mass Spectrometry (ICP-MS) (Perkin Elmer NexION 2000).

The process electrolyte was analyzed in terms of its chemical composition before and after ECM using mass spectroscopy with inductively coupled plasma (ICP-MS, NexION 2000, PerkinElmer LAS (Germany) GmbH, Rodgau, Germany). The advantage of this analysis is, on the one hand, to obtain information about the amount of material removed during ECM, and on the other hand, it makes it possible to draw conclusions on the material removal mechanism. Electrolyte samples were taken after reaching stationary ECM process conditions, which means for ECM-A after a period of 80 s and for ECM-B after a period of 10 s. Before ICP-MS measurements, the samples were diluted with 2% nitric acid in a ratio of 1 to 50.