Benefits of the Agilent 8900 ICP-QQQ with MS/MS operation for routine food analysis

Significance of the Topic

The accurate and reliable measurement of both toxic elements (As, Hg, Cd, Pb) and essential micronutrients (Se, Na, Mg, K, Ca) in foodstuffs is vital for public health and compliance with tightening regulatory limits. Traditional ICP-MS methods can struggle with complex, high-matrix food digests and spectral interferences, motivating enhanced techniques that deliver both high throughput and robust interference removal.

Objectives and Study Overview

This study evaluates the performance of the Agilent 8900 Triple Quadrupole ICP-MS (ICP-QQQ) operated in MS/MS mode for routine analysis of 30 elements in a range of food certified reference materials (CRMs). Special attention is paid to overcoming doubly charged rare-earth element (REE) interferences during As and Se determination.

Methodology

The analytical workflow combined closed-vessel microwave digestion, multi-element calibration, and tandem quadrupole interference removal:

• Sample preparation: Approximately 1.0 g of flour CRMs or 0.5 g of leaf CRMs digested with 6 mL HNO₃ and 1 mL HCl in a Milestone ETHOS 1 microwave system (200 °C, 15 min).
• Calibration and internal standards: Multi-element standards prepared in 6% HNO₃/1% HCl; online internal standards (Li, Sc, Ge, Rh, In, Tb, Lu, Bi, Ir) added to correct signal variation.
• Analysis sequence: Initial multi-level calibration, initial QC checks (ICB, ICV), twelve sample blocks (10 samples + 2 blanks each), and periodic QC blocks (CCB, CCV) over ~15 h; 183 total analyses, ~5 min per sample.
• Cell gas modes: Helium KED mode for general polyatomic removal; oxygen mass-shift (MS/MS) mode to convert As⁺ and Se⁺ to AsO⁺ (m/z 91) and SeO⁺ (m/z 94), eliminating doubly charged REE overlaps.

Used Instrumentation

The standard-configuration Agilent 8900 ICP-QQQ featured:

• Glass concentric nebulizer, quartz spray chamber, nickel interface cones.
• Octopole reaction cell (ORS4) for He and O₂ gas modes.
• Ultra High Matrix Introduction (UHMI) to tolerate up to 25% total dissolved solids.
• MassHunter software with Preset Methods and automated lens tuning.

Main Results and Discussion

Key performance metrics included:

• Internal standard stability: All ISTDs within ±20% of initial calibration over 15 h.
• Continuing calibration verification: CCV recoveries within ±10% for all elements.
• Detection limits: Single-quad He mode and MS/MS O₂ mode yielded low-ppb to sub-ppb limits (e.g., Se MS/MS DL ~0.05 ppb).
• CRM recoveries: Mean element recoveries of 90–110% for major and trace elements across five food CRMs.
• As and Se accuracy: Single-quad He mode showed positive bias in high-REE CRMs (Apple and Tomato Leaves) while MS/MS O₂ mass-shift delivered accurate results by removing Zr⁺ and Mo⁺ interferences.

Benefits and Practical Applications of the Method

The Agilent 8900 ICP-QQQ with MS/MS operation and UHMI technology offers:

• Robust, high-throughput multi-element measurement in challenging food digests.
• Superior spectral interference removal, ensuring confidence in low-level As and Se determinations.
• Automated tuning and preset methods reduce method development time and operator dependence.
• Compatibility with QA/QC workflows in food safety laboratories and regulatory testing environments.

Future Trends and Opportunities

Advancements may include integration with chromatographic separations for element speciation, further miniaturization of sample introduction systems to reduce dilution, and coupling with laboratory information management systems for fully automated, high-frequency monitoring of food and environmental samples. Continued expansion of reaction-cell chemistries and real-time interference diagnostics will broaden applicability to emerging contaminants.

Conclusion

The Agilent 8900 ICP-QQQ in MS/MS mode, combined with UHMI, delivers the matrix tolerance, sensitivity, and interference control necessary for routine multi-element food analysis. Its ability to resolve REE overlaps in As and Se measurements enhances data accuracy and regulatory compliance across diverse and complex food matrices.

References

• Ed McCurdy and Glenn Woods. J. Anal. At. Spectrom., 2004, 19, 607–615.
• Brian P. Jackson et al. J. Anal. At. Spectrom., 2015, 30, 1179–1183.
• Kazuhiro Sakai. Agilent Application Note, 2015, 5991-6409EN.
• Agilent 8800 ICP-QQQ Application Handbook, 2nd Edition, 2015, 5991-2802EN.
• Lieve Balcaen et al. Anal. Chim. Acta, 2014, 809, 1–8.
• S.D. Fernandez et al. Geochem. Geophy. Geosy., 2015, 16, 2005–2014.
• Takeshi Ohno and Yasuyuki Muramatsu. J. Anal. At. Spectrom., 2014, 29, 347–351.
• Clarice D.B. Amaral et al. Anal. Methods, 2015, 7, 1215–1220.
• Erik H. Larsen and Stefan Sturup. J. Anal. At. Spectrom., 1994, 9, 1099–1105.
• Maurizio Pettine et al. Anal. Chim. Acta, 2007, 599, 191–198.
• Wim Proper et al. Agilent Application Note, 2014, 5991-4257EN.