Direct quv water purification system

Experiments were carried out with ultrapure water (resistivity >18.2 MΩ∙cm⁻¹) obtained from a Millipore (Merck, Darmstadt, Germany) Direct-Q^® UV water purification system. 2,2′-Azobis(2-methylpropionitrile) (AIBN) (98%, Sigma-Aldrich, Munich, Germany, stored at 4 °C), 2-cyano-2-propyl benzodithioate (CPBD) (>97%, Sigma-Aldrich, Munich, Germany, stored at 4 °C), tetrahydrofuran (THF) (99.8%, Merck) and N,N-dimethylformamide (DMF) (>99.5%, Merck) were used without further treatment and purification. Styrene (99%, Sigma-Aldrich, contained methyl ether hydroquinone as an inhibitor, stored at 4° C) was freshly percolated through a column of basic aluminum oxide (>98%, Sigma-Aldrich) prior to use to remove the inhibitor methyl ether hydroquinone. 1,4-Dioxane (DOX) (>99.5%, VWR Chemicals, Darmstadt, Germany) was stored over KOH pellets (>85%, Merck) and freshly percolated through a column of aluminum oxide to remove peroxides. 3-Vinylpyridine (3VP) (97%, TCI Deutschland GmbH, Eschborn, Germany) was stored and transferred under a nitrogen atmosphere. All other chemicals were used as received.

Halloysite was obtained from the “Dunino” strip mine, Intermark Company, Legnica, Poland. Phenol ≥ 99%, 2-, 3-, 4-chloroPhenol ≥ 99%, 2-, 4-dichloroPhenol ≥ 99% were purchased from Sigma-Aldrich, Poznań, Poland. Hexadecyltrimethylammonium bromide ([(C₁₆H₃₃)N(CH₃)₃]Br and 2-, 4-, 6-trichlorofenol ≥ 98% were acquired from MERCK, Darmstadt, Germany. Sodium chloride 95% was from Avantor Performance Materials Poland S.A, Gliwice, Poland. Deionized water (1.74 μs∙cm⁻¹, temp. 25 °C) (Direct-Q UV Water Purification System, MerckMillipore, Burlington, Massachusetts, USA) was used through all experiments.

Ultrapure Type 2 water with a resistivity of 18.2 MΩ/cm, produced by a Merck Direct–Q UV water purification system (Merck KGaA, Darmstadt, Germany), was used for all applications. The trace metal grade HNO₃ was from Fisher Scientific, and the multi-element calibration standard and the ICP-MS internal standard mix were from Agilent Technologies.
Inductively coupled plasma mass spectrometry (ICP-MS) on Agilent 7800 series instrument was used to measure the metal content in wt Cu,Zn-SOD1 and G93A mutant samples. Metal concentrations were determined by the external calibration method by using multi-element calibration standard solutions in the range of 0.50–50 ppb in 2% trace metal grade HNO₃. The protein samples were diluted in 2% HNO₃ to a final concentration of 0.1 μM and 0.3 μM. The measurements were performed in He mode. For the ICP-MS instrument control Agilent MassHunter 4.4 software version C.01.04 was used under the following conditions: RF power 1550 W, nebulizer gas flow 1.03 L/min, auxiliary gas flow 0.90 L/min, plasma gas flow 15 L/min, nebulizer type: MicroMist, isotopes monitored: Cu-63 and Zn-66. The obtained results were analyzed by the program Origin 9 Pro.