Determination of 20 Nutritional, Essential and Toxic Elements in Blood Serum by ICP-MS using Alkaline Dilution

Importance of the Topic

The elemental profile of blood serum is vital for clinical diagnostics, nutritional monitoring, and toxic exposure assessment. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) enables rapid, sensitive analysis of multiple elements in minimal serum volumes, improving laboratory efficiency and reducing patient sample requirements.

Objectives and Study Overview

This work demonstrates an alkaline dilution method for quantifying over 20 nutritional, essential, and toxic elements in blood serum using the Shimadzu ICPMS-2040 LF. Goals include minimizing serum consumption (~75 µL per analysis), achieving fast throughput (~2 min per sample), and maintaining accuracy without labor-intensive acid digestion.

Methodology

• Sample preparation: Twenty-fold dilution of serum with an alkaline diluent containing ammonia (25 % v/v), Triton X-100, EDTA (Na-free), and isopropanol to adjust pH, lyse cells, stabilize ions, and compensate carbon effects.
• Calibration: Matrix-matched serum calibrators (Levels 1–4) and controls (Levels 1–2) from Recipe ClinMass diluted identically, enabling precise quantification across clinically relevant ranges.
• Measurement conditions: AS-20 autosampler with ProActive Rinsing, cyclonic Twister spray chamber at 5 °C, coaxial nebulizer (~0.4 mL/min), argon dilution gas, and helium collision mode to suppress polyatomic interferences.
• Instrument settings: 6 mm sampling depth, 1.2 kW RF power, optimized argon flows (plasma, auxiliary, carrier, dilution), helium cell gas (6 mL/min), and element-specific integration times for a ~2 min cycle.

Instrumentation

• Shimadzu ICPMS-2040 LF with AS-20 round-table autosampler and dual-rinse configuration.
• Cyclonic Twister spray chamber, coaxial 07UES nebulizer, Minitorch torch, nickel cones.
• LabSolutions software for method control, calibration, and quality assessment.

Key Results and Discussion

• Method stability: Internal standard recoveries remained within ±5 % over 60 samples; serum controls tracked within reference ranges throughout the run.
• Sensitivity: Limits of quantification ranged from sub-ppb (Be, Cd) to low µg/L (Cu, Mg), covering typical serum concentrations.
• Throughput: ProActive Rinsing and <5 s gas switching achieved ~2 min per sample without carry-over.
• Interference management: Helium collision mode reduced polyatomic overlaps; hydrogen reaction gas in ICPMS-2050 LF eliminated gadolinium double-charged interference on selenium.

Advantages and Practical Applications

• Minimal serum volume (~75 µL) suits pediatric or limited-volume samples.
• High throughput (~30 samples/hour) supports clinical, veterinary, and research laboratories.
• Robust operation with argon dilution and ProActive Rinsing avoids complex sample loops.
• Comprehensive elemental panel including Ag, As, Ba, Be, Bi, Cd, Co, Cu, Fe, Hg, I, Mg, Mo, Pt, Sb, Se, Sn, Tl, V, and Zn.

Future Trends and Opportunities

• Expand panels to include Ni, Cr, Mn and other trace elements.
• Adopt alternative reaction gases (e.g., NH3, O2) for targeted interference removal.
• Integrate automation and AI for real-time data evaluation and quality control.
• Develop compact ICP-MS platforms for point-of-care elemental testing.

Conclusion

The alkaline dilution ICP-MS method on the Shimadzu ICPMS-2040 LF delivers accurate, high-throughput analysis of 20+ elements in blood serum with minimal sample volumes and rapid cycle times. Collision/reaction gas strategies ensure robust interference suppression, making this approach highly suitable for routine clinical and research applications.

References

1. Recipe Chemicals + Instruments GmbH, Trace Elements in Plasma/Serum, Instruction Manual.
2. Inductively Coupled Plasma Mass Spectrometry: Introduction to Analytical Aspects, Clinical Biochemistry Reviews, 2019, 40(3), p. 126–132.
3. Shimadzu Corporation, Technical Note SPPD-9059A, Interference Correction for Doubly Charged Ions.