Routine Elemental Analysis of Dietary Supplements using an Agilent 8900 ICP-QQQ

Importance of the Topic

Dietary supplements are increasingly popular worldwide as consumers seek to fill nutritional gaps. Because these products may become contaminated with toxic elements such as arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg) during production or from raw materials, accurate and sensitive elemental analysis is essential for ensuring product safety and regulatory compliance.

Study Objectives and Overview

This application note evaluates the performance of the Agilent 8900 triple quadrupole ICP‐MS (ICP-QQQ) for routine determination of As, Cd, Pb and Hg in dietary supplement matrices. The primary goals are to demonstrate interference removal (especially doubly charged and oxide species), achieve low detection limits, and verify accuracy using standard reference materials (SRMs) and commercial supplements.

Instrumentation Used

• Agilent 8900 Triple Quadrupole ICP-MS with UHMI technology.
• Standard sample introduction: glass concentric nebulizer, quartz spray chamber, Ni interface cones.
• MassHunter software with preset plasma conditions (HMI-4) and Quick Scan qualitative screening.

Methodology

Samples—including NIST SRMs 1515 (Apple Leaves), 1573a (Tomato Leaves), 3280 (Multivitamin Tablets) and five commercial supplements—were digested via microwave in nitric and hydrochloric acids. Final digests were diluted to match acid content. The instrument was operated both in single quadrupole helium collision mode (He mode) and MS/MS mode using O₂ cell gas (mass shift). Calibration standards and internal standards (Ge, In, Tl, Bi) were matrix-matched. Method detection limits (MDLs) and limits of quantitation (MLOQs) were established from preparation blanks.

Main Results and Discussion

• Calibration: Linear response for As and Cd in both He and MS/MS O₂ modes.
• Detection limits: MS/MS O₂ mode improved MDLs by up to four‐fold for As and Cd relative to He mode.
• SRM recoveries: All analytes in three NIST materials fell within ±10% of certified values. MS/MS O₂ mode notably reduced As bias in REE-rich leaf materials.
• Commercial samples: Spike recoveries for all elements were within ±10% using MS/MS O₂. He mode alone suffered from suppressed As recoveries in high Co matrices and Cd in high Mo matrices.
• Quick Scan screening: Identification of potential oxide interferences (e.g. CoO⁺, MoO⁺) allows targeted application of MS/MS mass shift or mathematical corrections in single quadrupole ICP-MS.

Benefits and Practical Applications

• Reliable low‐level quantitation of regulated elements in complex matrices.
• Effective elimination of doubly charged and oxide interferences without extensive method development.
• Compliance support for regulatory standards (USP <2232>, cGMP, EU labeling rules).
• Streamlined workflow via preset plasma conditions and automated tuning.

Future Trends and Opportunities

As consumer demand grows, analytical laboratories will benefit from further automation of sample introduction and cell gas selection. Advances in collision/reaction cell chemistries may extend interference removal to additional challenging isotopes. Coupling ICP-QQQ with speciation techniques or hyphenated separations will broaden its use in nutritional quality control and toxicology. Miniaturized or portable ICP-MS systems may eventually support on-site testing of supplements and raw materials.

Conclusion

The Agilent 8900 ICP-QQQ, operated in MS/MS mode with O₂ cell gas, delivers robust determination of As, Cd, Pb and Hg in dietary supplements. It overcomes spectral interferences found in high-matrix samples, achieves trace‐level detection, and provides accurate recoveries in reference materials and commercial products. This approach simplifies compliance testing and enhances confidence in consumer safety.

References

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2. US FDA guidance on dietary supplements and cGMP requirements.
3. EFSA overview of food supplement regulations.
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