Determination of More Than 25 Nutritional, Essential and Toxic Elements in Whole Blood by ICP-MS Using Alkaline Dilution

Significance of the Topic

Whole-blood multi‑element analysis by inductively coupled plasma mass spectrometry (ICP‑MS) provides an integrated view of both cellular and extracellular compartments and is therefore highly relevant for nutritional assessment, toxicology and biomonitoring. Rapid, robust and low‑contamination sample handling combined with ICP‑MS sensitivity enables simultaneous quantification of nutritional, essential and toxic elements at biologically meaningful concentrations. The alkaline dilution approach reduces sample processing time and improves stability and washout (notably for mercury) compared with conventional acidic workflows, making it attractive for high‑throughput research laboratories.

Objectives and Study Overview

The application note presents a validated workflow for the determination of more than 25 elements in whole blood using the Shimadzu ICPMS‑2050 LF. Key goals were to: simplify sample preparation via a 20‑fold alkaline dilution, achieve low limits of quantification compatible with common clinical/research reference ranges, demonstrate method stability over a typical batch (~100 samples), and resolve common spectral interferences using collision/reaction and high‑resolution modes.

Methodology

- Sample preparation: whole blood and matrix‑matched calibrators/controls (Recipe ClinCal® and ClinCheck®) are diluted 1:20 with an alkaline diluent formulated from ultrapure water, ammonia (to set alkaline pH), Tergitol (to lyse and homogenize), EDTA (for ion stabilization) and isopropanol (to compensate carbon enhancement effects). Vortex homogenization is used prior to analysis. - Calibration: matrix‑matched calibrators spanning blank to 100% (defined as 0.5 mL in 10 mL before the 20× dilution) are used; calibration curves are 1/I weighted to improve low‑end precision. - Internal controls: whole blood control levels I–III were measured routinely during runs to monitor trueness and stability. - Interference management: a combination of He collision mode, H2 reaction mode and high‑resolution measurement (for selected isotopes such as 55Mn) plus inter‑element correction (IEC) was applied to remove polyatomic and doubly charged interferences (examples: 156Gd→78Se and 56Fe→55Mn).

Used Instrumentation

The method uses the Shimadzu ICPMS‑2050 LF configured for bodily fluid analysis with attention to low carryover and small sample volumes. Key hardware and conditions included:

• Autosampler: AS‑20 (covered round table, dual rinse, low dead volume)
• Sample probe: Inert Guardian probe with inline filter
• Nebulizer/chamber: coaxial nebulizer (~0.4 mL/min) with cyclonic Twister chamber at 5 °C
• Torch and cones: Shimadzu Minitorch; nickel cones; sampling depth ~9.0 mm
• Gas flows and power: RF 1.20 kW; plasma Ar ~9.0 L/min; auxiliary Ar ~1.10 L/min; carrier Ar ~0.47 L/min; dilution Ar ~0.38 L/min
• Collision/reaction cell gases: He ~6.0 mL/min and H2 ~7.0 mL/min (low flow to effectively remove interferences)
• Peristaltic pump: 4‑channel, 12‑roller at 20 rpm; extended rinsing and ProActive Rinsing functions used to reduce carryover
• Software: LabSolutions ICPMS for method control, QC tracking, and internal standard monitoring

Measurement settings included tailored integration times per isotope and selection of isotope or summed isotopes (e.g., 206+207+208 Pb) to optimize sensitivity and accuracy.

Main Results and Discussion

- Element panel: >25 elements quantified, including Ag, Al, As, Ba, Ca, Cd, Co, Cu, Fe, Hg, I, K, Mg, Mn, Mo, Na, P, Pb, Pd, Pt, Sb, Se, Sn, Sr, Tl, Zn. - Sensitivity and limits: method LODs and LOQs (derived from calibration blank SD) are compatible with common reference ranges for all reported elements; LOQs ranged from sub‑µg/L for many trace elements to sub‑mg/L for major elements (see summary table in results). Increased integration time is recommended for Mo, Pd and Sn to further improve sensitivity. - Stability: internal standard recoveries remained stable across a 100‑sample run; whole blood control materials traced to expected values throughout batches, supporting robust daily operation. - Interference removal: hydrogen reaction mode effectively removed 156Gd interference on 78Se; high‑resolution measurement combined with IEC removed 56Fe interference on 55Mn even at elevated Fe concentrations (data showed accurate Mn recovery with up to hundreds of ppm Fe). These approaches allow reliable trace determinations in the complex whole‑blood matrix. - Practical performance: the Minitorch plasma and low gas flows reduce argon consumption and power draw without compromising performance; instrument features such as quick gas switching (<5 s) and proactive rinsing shorten sample cycle times and lower carryover risk.

Benefits and Practical Applications

- Minimal sample preparation: direct alkaline dilution (1:20) avoids acid digestion, reduces processing time and contamination risk, and is suited for high throughput research workflows. - Improved analyte stability and washout: alkaline matrix stabilizes elements and enhances mercury washout versus acidic media. - Comprehensive panel: simultaneous quantification of nutritional, essential and toxic elements supports nutritional studies, exposure assessment and biomonitoring. - Robust interference control: use of collision/reaction modes, high resolution and IEC yields reliable results even in challenging matrices with variable major element content (e.g., variable Fe levels). - Cost and throughput advantages: lower argon and power consumption plus automated rinsing and fast gas switching improve lab efficiency and reduce running costs; matrix‑matched calibrators and in‑run QC streamline routine operation.

Future Trends and Opportunities

- Wider adoption of alkaline dilution and matrix‑matched calibrators will simplify multi‑element assays in clinical research and population studies. - Further automation (robotic sample handling, integrated QC tracking) and software support (real‑time QC flagging, IEC automation) will increase throughput and reliability. - Method extensions: inclusion of isotope dilution strategies for absolute accuracy, expansion to additional elements/isotopes, and application to smaller sample volumes or micro‑sampling approaches. - Instrument advances: continued reductions in argon and power consumption, improved cell chemistries for more challenging interferences, and enhanced sensitivity to push method limits lower will broaden applications.

Conclusion

The presented ICPMS‑2050 LF method using alkaline dilution delivers a practical, sensitive and robust workflow for quantifying more than 25 elements in whole blood. Combining matrix‑matched calibration, collision/reaction/high‑resolution interference control and operational features that minimize carryover and argon usage yields reliable results suitable for research applications in nutritional assessment and biomonitoring. The approach balances throughput, cost‑efficiency and analytical quality while avoiding labor‑intensive digestion procedures.

References

1. Blood collection device components: issues, innovations, and recommendations for clinical laboratories and manufacturers — a narrative review, Journal of Laboratory and Precision Medicine, Vol 10 (2025).
2. Inductively Coupled Plasma Mass Spectrometry: Introduction to Analytical Aspects, Clinical Biochemistry Reviews, 40(3), 2019, p. 126.
3. Shimadzu Application Notes: Determination of 23 Nutritional, Essential and Toxic Elements in Urine by ICP‑MS Using Alkaline Dilution; Determination of 20 Nutritional, Essential and Toxic Elements in Blood Serum by ICP‑MS Using Alkaline Dilution; ICP‑MS Analysis of 25 Elements in Blood Serum Using Recipe ClinMass® Complete Kit.