May 28, 2026
Inductively coupled plasma mass spectrometry (ICP-MS)
- 1Columbia University
Protocol Citation: Christine Chio 2026. Inductively coupled plasma mass spectrometry (ICP-MS). protocols.io https://dx.doi.org/10.17504/protocols.io.n92ldob8ng5b/v1
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working
Created: May 28, 2026
Last Modified: May 28, 2026
Protocol Integer ID: 318135
Keywords: plasma mass spectrometry, coupled plasma mass spectrometry, concentration of trace element, trace element, icp, tissue
Abstract
ICP-MS is used to measure the concentration of trace elements in tissues.
Materials
Ultrapure water (≥18.2 MΩ cm), Ultrapure nitric acid, MARS 6 Digestion Microwave System (CEM Corp., Matthews, USA), EasyPrep microwave vessels, 15 mL metal-free centrifuge tubes, Gallium (Ga) and yttrium (Y) internal standard mix, Labcon metal-free tubes (Labcon, Petaluma, USA), Certified reference materials (CRMs) QM-S-Q2207 and QM-S-Q2208, Agilent 8900 ICP-MS, MicroMist glass nebulizer, Glass double pass spray chamber, Platinum/copper sampler and skimmer cones, Quartz plasma torch,
Sample preparation
Ultrapure water (≥18.2 MΩ cm) was used for reagents and standard solutions. Ultrapure nitric acid was employed for sample digestion and standard solutions. Mouse tissues were prepared for total quantitative analysis of copper (Cu), zinc (Zn), iron (Fe), and selenium (Se) using a microwave-assisted acid digestion method. Samples were defrosted, and wet tissues were weighed with a precision of ±0.01 mg into acid-cleaned 7 mL PFA vials. Subsequently, 0.5 mL of HNO3 was added to each vial. For quality control and method assessment, bovine liver (NIST 1577C) from the National Institute of Standards and Technology was used as a reference material. Blank samples consisting only of 0.5 mL of HNO3 were also processed (n = 46). The vials were capped and submerged in larger EasyPrep microwave vessels, and the digestion was performed using the MARS 6 Digestion Microwave System (CEM Corp., Matthews, USA). The temperature was ramped up in four stages to 180°C and held for 20 minutes. After cooling, the digested samples were transferred to 15 mL metal-free centrifuge tubes. Then, 50 µL of a gallium (Ga) and yttrium (Y) internal standard mix (500 µg/L stock) was added, and the samples were diluted with ultrapure water to a final volume of 5 mL. Mouse serum samples were prepared by mixing 0.1 mL of serum with 50 µL of a Ga and Y internal standard solution (500 µg/L stock) in 15 mL metal-free tubes (Labcon, Petaluma, USA). The resulting mixture was then diluted to a final volume of 5 mL with a diluent of 1% HNO3, 0.02% Triton X-100, and 500 µg/L gold. For quality control and method validation, certified reference materials (CRMs) QM-S-Q2207 and QM-S-Q2208 from the Quebec Multi-element External Quality Assessment Scheme from the Institut National de Santé Publique (Centre de Toxicologie du Québec, Canada) were used. Method blanks were prepared in the same manner as the serum samples but without the addition of sera. For the metal analysis of the MSRA immunoprecipitates, 0.1 mL of solution was transferred to 15 mL metal-free tubes and diluted to a final volume of 5 mL with a diluent of 10% HNO3 and 500 µg/L gold.
ICP-MS measurement
An Agilent 8900 inductively coupled plasma mass spectrometer (ICP-MS) equipped with an octopole reaction system was used for the analysis. The standard ICPMS/MS configuration for all samples included a MicroMist glass nebulizer, a glass double pass spray chamber, platinum/copper sampler and skimmer cones, and a quartz plasma torch with an inner diameter of 2.5 mm. The operating parameters for the ICPMS/MS were as follows: the radiofrequency (RF) power was set to 1,550 W, the plasma gas flow rate was 15.0 L/min, and the auxiliary gas flow rate was 0.9 L/min. The spray chamber temperature was maintained at 2 °C. External eight-point calibration was performed using matrix-matched solutions. For tissue and MSRA immunoprecipitate samples, the calibration matrix consisted of 10% vol. HNO3, 500 µg/L gold, and 5 µg/L Ga and Y internal standard mix. For serum samples, the calibration matrix consisted of 1% vol. HNO3, 500 µg/L gold, and 5 µg/L internal standard. Cu, Fe, Se, and Zn were measured in various gas modes. Cu was analysed in helium mode on mass 63, while Zn was measured on mass 66 in ammonia mode. Fe was measured in oxygen mode, and Se was measured in oxygen mode by a mass shift from 80 to 96. The stabilization time between each gas mode was 10 seconds. The integration times for all masses were set to 0.4 seconds, except for Fe, which had an integration time of 0.1 seconds. The limit of detection (LOD) was calculated using the formula: LOD = 3.33 × standard deviation from blank measurements. The LODs for microwave-digested tissues were as follows: 3.9 µg/L for Fe, 19 µg/L for Zn, and 0.01 µg/L for Se. For the serum samples, the LODs were 0.2 µg/L for Fe, 0.05 µg/L for Cu, 0.3 µg/L for Zn, and 0.02 µg/L for Se. The accuracy for CRM NIST 1577c was 96% for Fe, 81% for Cu, 92% for Zn, and 95% for Se, as percentages of certified values. The accuracy for the serum CRMs (QM-S-Q2207 and QM-S-Q2208) was 86-89% for Cu, 102-105% for Zn, and 106-108% for Se, respectively. Fe was not certified for the serum CRMs.