Agilent 7500ce icp ms

To determine the Ca content in the wheat root-tip meristematic region, 200 μg of the control and 1.5 mM LaCl₃-treated roots were completely dried and then digested in 5 mL concentrated nitric acid + 1 mL H₂O₂. Digested samples were diluted with ultra-pure water to 50 g. The Ca content in each group was measured using an Agilent 7500ce ICP-MS (Agilent Technologies, Santa Clara, USA).

The children collected their urine over the same 24-h time period as their weighed diet record and duplicate diet. The time of the first void of the day was recorded by the caregivers, and this urine was discarded. All urine for the remaining 24-h (including the first void of the following morning) was collected into a 2L screw-top bottle with the aid of a funnel. Any missing void was noted. The total volume (weight) of urine was recorded by the researchers. Completeness of the 24-h urine samples was assessed by comparing them to the lower limit for children older than 6 years (9 mL/h) [23 ]. Samples that did not meet this criterion were excluded from analysis, as were samples where participants recorded missing more than one void in the 24-h period. Urine samples were analyzed for sodium, potassium, and iodine using inductively coupled plasma mass spectrometry (ICP-MS) (Agilent 7500ce ICP-MS, Agilent Technologies, Tokyo, Japan).

We collected blood and brain tissue for lead analysis at sacrifice after the cessation of the lead exposure from a subset of the mice in the cellular cohort (20 weeks old; n = 3–5 per genotype/sex/treatment). The Environmental Health Laboratory at the University of Washington measured blood lead levels using inductively coupled plasma mass spectrometry (ICP-MS; Agilent 7500ce, Agilent Technologies, Santa Clara, CA). The spatial distribution and semi-quantitative measurement of lead and zinc levels (ppm) in 30 μm brain hemisphere sections from 20-week-old ApoE4-KI control or lead-treated females was determined by laser ablation ICP-MS (LA-ICP-MS) using an NWR213 laser ablation system (ESI, Portland, OR) connected to an Agilent 7500ce ICP-MS (Agilent Technologies, Santa Clara, CA). Quantification was achieved using spiked protein matrix as external standards.

The amount of I in the milk at T0 and T8 was determined according to Fecher et al. (1998) with some modifications [18 (link)]. Briefly, for each sample, 0.5 g of milk were homogenized with tetramethylammonium hydroxide (0.25 M) and 2 mL of deionized water (30%). Then, samples were heated in a microwave (800 W) at 170 °C for 30 min. After cooling, samples were transferred into a sterile tube and diluted with distilled water to a final volume of 15 mL. After centrifugation at 12,000 rpm × min⁻¹ at room temperature for 10 min, samples were filtered through polytetra-fluoroethylene (PTFE) syringe filters (0.45 μm) and, finally, stored at 4 °C until analysis. A standard calibration curve was created using six calibration points equals to concentrations of 0, 5, 10, 25, 50, and 100 mg/L of I in tetramethylammonium hydroxide. For the carrier and gas formation, argon gas was used at flow rates of 1.05 and 0.2 L/min, respectively. The iodine content was determined by an inductively coupled plasma mass spectrometer Agilent 7500ce ICP-MS (Agilent Technologies, Palo Alto, CA, USA) at m/z = 127 and a total acquisition time of 21 s. Before the sequence analysis, the ICP-MS was auto-tuned by a solution containing 1 ppb of different metals (Li, Y, Ce, Tl, and Co).

Blood samples were collected from the antecubital vein. To minimize contamination, blood was collected in the royal blue stoppered trace element tubes (catalog #369737, BD Vacutainer™ glass sterile tube, Becton Dickinson Co., Franklin Lakes, NJ, USA) used for analysis. Approximately 250 μL of serum was separated and immediately stored at −70 °C until the moment of analysis. Serum Co, Cu, Zn, and Se levels were analyzed using an Agilent 7500ce ICP-MS (Agilent Technologies, Inc., Tokyo, Japan). National Institute of Standards and Technology-traceable 10 mg/L and 1000 mg/L elemental standards were used for preparation of multi-element calibration standards. Both intra- and inter-assay imprecision were <10% of the coefficient of variation. Accuracy was assured by the Proficiency Testing/Quality Management program of the Unites States College of American Pathologists survey (CAP). The CAP survey periodically provides quality control samples, which were shared among laboratories, and acceptable criteria with target values. High or low trace element status groups were defined when the serum concentration of a subject was outside the reference range, which was determined based on our previous study in healthy Korean adults [27 ].