Excellent choices for environmental applications

Significance of the Topic

High-matrix samples in environmental, geological or clinical analysis often challenge conventional ICP-MS: spectral interferences limit low-level detection while intense matrix elements or analytes can overload the detector. Laboratories have traditionally resorted to graphite furnace AA for ultratrace elements and ICP-OES for major elements, complicating workflows and reducing productivity. The Agilent 7500ce ICP-MS, combining the Integrated Sample Introduction System (ISIS) and the Octopole Reaction System (ORS), addresses these limitations by extending both the lower and upper practical dynamic range, improving matrix tolerance, and enabling semiquantitative screening of unknown samples.

Objectives and Study Overview

This work details how the Agilent 7500ce ICP-MS achieves:

• Interference-free trace analysis of elements such as Se, Cr, V, Cu, Zn in up to 1% strong acid organics
• Accurate high-concentration measurement of matrix elements (Na, K, Ca, Mg, Fe) at 100s–1000s ppm
• Simple rapid semiquantitative screening across the mass range without species-specific cell chemistries

Key innovations include low-flow nebulization and back-flush sample uptake (ISIS), and interference removal by kinetic energy discrimination (KED) in helium collision mode (ORS).

Methodology and Instrumentation

The system uses:

• All-solid-state 27 MHz plasma at 1550 W, cooled spray chamber, low-flow nebulizer, and backflush sample introduction (ISIS)
• Pressurized octopole cell (ORS) outside the high vacuum, with three modes of operation: normal (no cell gas), hydrogen reaction (3–5 mL/min H2), and helium collision (4 mL/min He)
• Soft-extraction and the ShieldTorch design to maintain ion energy spread < 0.5 eV
• Synchronous SIM/Scan and automated gas and bias autotuning to optimize interference removal

Typical test matrices include up to 1% HNO3, HCl, H2SO4, BuOH with ca. 100 ppm Ca and Na, and semiquant synthetic standards. Calibration and internal standardization use SPC-grade multi-element solutions.

Main Results and Discussion

• Hydrogen reaction mode effectively eliminates argon-based polyatomic interferences (e.g. ArCl+, ArO+) on m/z 40, 52, 56, 78, 80, enabling trace Se, Cr and Fe measurement under extreme matrix conditions
• Helium collision mode with KED removes all polyatomic interferences from unknown matrices, without creating new reaction-generated species or consuming analyte, preserving high analyte sensitivity
• Using hydrogen mode to attenuate high-abundance matrix elements extends the upper linear range for Na, K, Ca, Mg, Fe by >10×, while maintaining ppt limits for trace elements
• Semiquantitative screening across 80 elements was demonstrated in complex matrices with no sample‐specific interference corrections
• Integrated Sample Introduction (ISIS) reduces memory effects and matrix buildup, shortening rinse-out and eliminating the need for sample matching or extensive dilution

Benefits and Practical Applications of the Method

The 7500ce ICP-MS with ORS and ISIS:

• Simplifies laboratory workflows by replacing multi‐technique approaches (GFAA, ICP-OES) with a single ICP-MS system
• Reduces sample preparation, maintains
• Improves reliability and uptime by enabling vent‐free source maintenance and minimal sample carry‐over
• Offers robust performance in unknown, variable matrices, ideal for environmental, clinical, geological, and food safety applications

Future Trends and Applications

Continued innovations in collision/reaction cell design and sample introduction will further enhance interference removal and dynamic range. Coupling fast chromatographic separations (GC, LC) to 7500ce will allow high‐throughput speciation and organic analysis with trace elemental detection. Expanded use of kinetic energy discrimination for complex reaction pathways and isotope dilution quantitation will improve accuracy in ever more challenging environmental and biomedical matrices.

Conclusion

The Agilent 7500ce ICP-MS, through the synergistic combination of ISIS and ORS technologies, achieves unprecedented practical dynamic range, matrix tolerance, and throughput in environmental analysis. Interference removal via KED in helium mode and signal attenuation by hydrogen mode enable accurate measurement of trace and major elements in complex matrices, eliminating the need for multiple techniques and ensuring reliable quantitation across four orders of magnitude in a single run.

References

1. “Real World Analysis of Trace Metals in Drinking Water using the Agilent 7500ce ICP-MS with Enhanced ORS Technology,” Agilent Technologies publication 5989-0870EN
2. “Analysis of Ultra High Matrix Environmental Samples with the Agilent 7500ce ICP-MS with Enhanced ORS Technology,” Agilent Technologies publication 5989-0915EN