Determination of Essential and Toxic Elements in Urine by ICPMS-2050

Significance of the Topic

Biomonitoring of essential and toxic trace elements in human urine is a critical approach for assessing environmental and occupational exposure. Urine offers a non-invasive sample matrix in which many elements are excreted in their native or metabolized forms. Traditional mono-element techniques such as graphite furnace AAS can be time-intensive when measuring multiple analytes, whereas modern ICP-MS platforms enable rapid, multi-element quantitation with high sensitivity and broad dynamic range.

Objectives and Study Overview

This application study aimed to develop and validate a method for simultaneous determination of nineteen target elements (including Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, Se, Tl, V and Zn) in certified reference urine material. The work focused on streamlining the workflow, ensuring accuracy and robustness, and minimizing consumable costs using the Shimadzu ICPMS-2050 system.

Methodology

Certified reference urine controls were reconstituted and diluted 15-fold using an acid diluent composed of high-purity nitric acid, Triton X-100, 1-butanol and gold solution to stabilize analytes and enhance sensitivity. Calibration standards were prepared by serial dilution of single-element stock solutions in the acid matrix across appropriate concentration ranges. An internal standard mix of Bi, Ge, In and Sc (10 µg/L each) was added to all standards, samples and rinses for drift and matrix compensation. Key analytical parameters included a sampling depth of 7 mm to reduce matrix load, optimized argon flows, helium and hydrogen collision gases for interference removal, and an energy filter set to 7 V.

Used Instrumentation

• ICP-MS: Shimadzu ICPMS-2050
• Nebulizer: Micromist DC
• Spray chamber: Cyclonic
• Plasma torch: Mini-torch (reduced argon consumption)
• Cones: Nickel sampling and skimmer cones
• Autosampler: AS-20

Results and Discussion

Calibration curves for all elements exhibited excellent linearity (R>0.999). Limits of detection and quantitation ranged from low ng/L to single µg/L levels. Analysis of two levels of urine CRM yielded recoveries between 83 % and 118 %, demonstrating method accuracy. Spike recovery tests on Level I CRM returned 93 %–104 %, indicating minimal matrix effects. The internal standard intensity fluctuation graph over a 30-sample batch showed variations within ±20 %, confirming the method’s stability and robustness over extended runs.

Benefits and Practical Applications

• Simultaneous multi-element detection reduces analysis time.
• High sensitivity and wide linear dynamic range cover low to high concentrations.
• Reduced argon consumption lowers operational costs.
• Internal standard monitoring ensures reliable correction for drift and matrix interferences.
• Streamlined workflow with certified controls minimizes user error.

Future Trends and Opportunities

Advances in collision/reaction cell chemistries and miniaturized ICP-MS designs may further enhance interference removal and reduce gas consumption. Automation of sample preparation and integration with chromatographic separation could expand capabilities for speciation studies. The development of expanded certified reference materials and matrix-matched calibrations will support broader application in clinical, environmental and occupational health contexts.

Conclusion

The Shimadzu ICPMS-2050 method provides a robust, accurate and cost-effective solution for multi-element urine biomonitoring. High linearity, low detection limits, strong recoveries and stable internal standard performance make it suitable for routine QA/QC and research applications.

Reference

1) G.V. Iyengar. Reevaluation of the trace element content in Reference Man. Radiat Phys Chem, 51(4-6):545-560 (1998).