Agilent 7700 icp ms

Staphylococcus aureus Xen36 (PerkinElmer, Part Number 119243), a methicillin sensitive, beta-lactamase positive strain [25 ], that is engineered for bioluminescence to facilitate in vivo infection studies is used as a representative isolate [26 (link)]. Antibiotic assays were performed in BBL Cation-Adjusted Mueller Hinton II Broth (MHB; Fort Richard, Auckland). Cefazolin was purchased from Sigma-Aldrich. Native bovine lactoferrin was supplied by Fonterra, NZ. Iron-loaded lactoferrin (approximately 80% iron saturation) was prepared by incubating 100 mg/ml native lactoferrin with 2× molar equivalents of Fe₂Cl₃ and NaHCO₃ for 24 hours as described in [27 (link)], followed by three 12-hour rounds of dialysis against 40 volumes of PBS to remove unbound iron and return to a neutral pH. Protein content was calculated from HPLC data (Fonterra) and Fe³⁺ content was verified using inductively coupled plasma-mass spectrometry (Agilent 7700 ICP-MS in He mode).

Tumors harvested on EDD17 were dried overnight at 80 °C, until constant weight was obtained. The dried samples were transferred to pressure vessels, added with ~3 mL nitric acid, and heated up to 150 °C for 30 min. Upon acid evaporation, freshly made aqua regia (3:1 HCl: HNO3 molar ratio was added to the samples for further digestion. The digested and dried samples were then added with 3 mL of 3% nitric acid solution. The amounts of gold and/or platinum were determined after analysis on Agilent 7700 ICP-MS, using standard calibration curves.

Se status was assessed on the basis of the concentrations of Se in plasma or serum.26 (link) Plasma or serum samples obtained from participating cohorts were stored at −70°C or −80°C refrigerators before and after use at the CCHMC Biobank (online supplemental table 1). To mitigate potential batch effect, samples from each site were randomised prior to analysis in batches. Inductively coupled plasma mass spectrometry (ICP-MS) measurements of Se concentrations in serum or plasma were performed using Agilent 7700 ICP-MS (Agilent Technologies) at the laboratory of Clinical Chemistry and Biochemistry, University of Cincinnati as described in detail in the protocol (online supplemental text 2) except the samples from Bangladesh (MDIG) which were analysed at the Centers for Disease Control and Prevention (Atlanta, GA).

For biochemical analysis, a pool of three liver pieces per tank were homogenized together, while three fillets per tank were individually homogenized (IKA T25 digital ULTRA-TURRAX, IKA Works, USA). The protocols described by Lowry et al. (25 (link)), Folch et al. (26 (link)), Dubois et al. (27 (link)), and AOAC (28 ) were followed to determine the levels of total protein, lipids, carbohydrates, and ash content in livers and fillets. Fatty acid profile was obtained as described by Ramos-Júdez et al. (29 (link)). In brief, transmethylated fatty acids from total lipids were extracted, purified, and finally quantified by gas-liquid chromatography on a Thermo Trace GC (Thermo Fisher, Spain) coupled to a TRACE™ TR-FAME GC Column (Thermo Scientific, Spain), using heneicosylic acid (21:0) as internal standard (ref. H5,149, Sigma-Aldrich, Spain).
Protein and lipid ADCs were calculated according to Cheng and Hardy (30 (link)) using Y₂O₃ as inert marker:
The Y₂O₃ concentration was determined using an Agilent 7700 ICP-MS (Agilent Technologies, USA).

ICP-MS was performed using Agilent 7700 ICP-MS. Mass Spectrometry (Santa Clara, CA, USA) tuned liquid: 7Li, 59Co, 89Y, 140Ce, 205Ti was used. The internal standard was 1 mg/mL indium solution. The conditions of detection are presented in Table 2. Digested sample solution was diluted before injection. The ICP-MS system was washed for 90 s between injections to reduce the memory effect.

Samples were weighed into 80 mL Teflon tubes and 7 mL of 69% Tracepur HNO3 (Merck) was added. The vessels were sealed and placed in a Maxi-44 rotor and digested in a Ethos-Up Microwave reaction system (Milestone SRL, Italy) at 180C for 20 min. The digest was diluted with 43 mL Type-1 water and a final weight was obtained. The solutions were quantitatively analysed for zinc on an Agilent 7700 ICP-MS in He mode to reduce polyatomic interferences. Calibration standards were prepared in a 10% HNO3 solution from 1000 ppm Single element standards (Inorganic Ventures, USA). A 20 ppb Y solution was used as an online internal standard to monitor for instrument drift and correct for matrix interferences. All results are in μg/g and are back-calculated to the original sample.

Inductively coupled plasma mass spectrometry (ICP-MS, Agilent 7700 ICP-MS, Santa Clara, CA, USA) was performed at the Arizona Laboratory for Emerging Contaminants to measure metal levels in diets, blood, and tissue from livers, spleens, and brains. Samples of each diet were digested in 3 mL concentrated nitric acid at room temperature overnight, followed by incubation at 85 °C for 4 h. Digested samples were then diluted to 3% nitric acid with Milli-Q water. 50 μL of each blood sample was digested in 1.95 mL 3% nitric acid and incubated at 85 °C for 4 h. Digested samples were centrifuged at 2000× g for 10 min and supernatant was collected.
Tissue samples were dried out through incubation at 85 °C for two days. Samples were then digested in 1 mL concentrated nitric acid at room temperature overnight, then at 60 °C for one day and finally at 80 °C until acid evaporated completely, with tubes vortexed daily. 300 μL concentrated nitric acid was diluted to 3% concentration with Milli-Q water for a final volume of 9 mL. Results were reported in ng/mL and multiplied by total volume, then divided by dry weight or μL to provide metal levels as ng/g dry tissue weight, ng/μL blood or μg/g diet sample weight.