Icp ms internal standard mix

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.

Realgar was purchased from Xi'an Yuelai Pharmaceutical Technology Co., Ltd. (Xi'an, China). Bovis Calculus Artifactus, Borneolum Syntheticum, Gypsum Fibrosum, Rhei Radix et Rhizoma, Scutellariae Radix, Platycodonis Radix, and Glycyrrhizae Radix et Rhizoma were provided by Beijing Tongrentang Group Co., Ltd. (Beijing, China). Before the experiment, all TCMs were inspected and confirmed to meet the standards of ChP. The reference standard solution of arsenic (1000 mg/L) was purchased from the National Institute of Metrology (Beijing, China). Trace metal-grade nitric acid was supplied by Fisher Chemical (Fair Lawn, USA). 1 μg/L tuning solution for ICP-MS with mixed elements (Ce, Co, Li, Mg, Tl, Y) and ICP-MS internal standard mix (100 mg/L of Bi, Ge, In, Li, Lu, Rh, Sc, Tb) were obtained from Agilent Technologies (Santa Clara, USA). Deuterium oxide (D₂O, 99.8%) and sodium 3-trimethylsilyl [2, 2, 3, 3-²H₄] propionate (TSP) were purchased from Alfa Aesar (Shanghai, China).