Ultra-fast ICP-OES determinations of soil and plant material using next generation sample introduction technology

Significance of the topic

Testing soils and plant tissues for major and trace elements is crucial for agricultural productivity, nutrient management, and food safety. Rapid, accurate analyses guide fertilizer application, monitor crop health, and detect contamination risks.

Objectives and study overview

The study evaluates a next-generation sample introduction system (SVS 2) coupled with an Agilent 720 ICP-OES to accelerate multi-element determinations in soil and plant matrices. It aims to minimize non-productive steps, enhance throughput, and maintain analytical performance.

Methodology and instrumentation

Samples of certified reference materials (NIST SRM 2710 and SRM 1571) underwent microwave-assisted acid digestion following US EPA Method 3051A. Key instrumentation and configurations:

• Microwave digestion: CEM Mars 5 with nitric and hydrochloric acid, two-stage program.
• ICP-OES: Agilent 720, axially viewed, CCD detector (167–785 nm), thermally stabilized, true simultaneous detection.
• Sample introduction: SVS 2 switching valve system with flow injection, high-speed positive-displacement pump, four-channel peristaltic pump, on-line internal standard (yttrium) and ionization buffer (cesium nitrate).

Main results and discussion

The SVS 2 reduced sample-to-sample cycle time to under 30 s—more than twice the throughput of conventional setups. Constant plasma flow and preemptive rinsing eliminated uptake delays and extended washout, while on-line internal standardization ensured signal stability. Recoveries of major, minor, and trace elements in soil and leaf reference materials were within 90–120% of certified leachable values, demonstrating accuracy despite minimal sample contact with pump tubing.

Benefits and practical applications

• High throughput: >2400 samples daily potential with continuous operation.
• Cost savings: reduced argon consumption, lower acid and standard usage, extended torch and tubing lifetimes.
• Improved plasma stability and minimal carry-over: consistent sample flow and inert pathways.
• Simple operation: minimal method setup, direct digestion extracts environmentally mobile fractions.

Future trends and potential applications

Advances may include automation integration with laboratory information systems, expanded multi-channel introduction for speciation studies, portable ICP-OES adaptations for field use, and enhanced data analytics using machine learning to optimize workflows and predictive maintenance.

Conclusions

The combination of microwave-assisted digestion and the SVS 2 with an Agilent 720 ICP-OES delivers rapid, reliable multi-element analysis of soils and plant materials. This workflow halves analysis time, maintains analytical quality, and reduces operating costs, meeting the high-throughput demands of modern agricultural testing laboratories.

References

1. Ryan A. Rapid measurement of major, minor and trace elements in plant and food material using the Agilent 730 ICP-OES.
2. Calderon V. Rapid measurement of major, minor and trace levels in soils using the Agilent 730 ICP-OES.
3. US EPA Method 3051A. Microwave assisted acid digestion of sediments, sludge and oils. Revision 1, January 1998.
4. CEM Microwave sample preparation notes for Mars 5 digestion system.