Determination of metals in wine using the Agilent 4100 Microwave Plasma-Atomic Emission Spectrometer

Significance of the topic

Determination of trace metals in wine is critical to quality control in winemaking because elements such as potassium, calcium, and iron can induce precipitation, turbidity, and flavor changes. Reliable monitoring of these metals ensures product consistency and consumer satisfaction while meeting regulatory and safety standards.

Objectives and overview

This study evaluates the Agilent 4100 Microwave Plasma–Atomic Emission Spectrometer (MP-AES) as a cost-effective, safe alternative for quantifying Ca, K, Na, Mg, and Fe in wine. The work compares MP-AES performance against conventional Flame Atomic Absorption (FAA) and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) techniques to assess accuracy, detection limits, and operational benefits.

Methodology and instrumentation

Sample preparation involved degassing commercial red and white wines, diluting samples 1:10 in 5% HNO₃ with 2% ethanol to match matrix composition, and adding ionization suppressants (Cs or Sr) via a T-piece. The Agilent 4100 MP-AES uses a robust magnetically excited nitrogen plasma, OneNeb nebulizer, double-pass glass cyclonic spray chamber, and an External Gas Control Module (EGCM) to prevent carbon deposition during analysis of alcohol-containing matrices. Comparative measurements were performed on an Agilent 240FS FAA and an Agilent 725 radial ICP-OES using optimized conditions for each technique.

Main results and discussion

MP-AES method detection limits ranged from 8 µg/L for Ca to 110 µg/L for K. Analysis of certified reference materials yielded recoveries between 94% and 110%, demonstrating accuracy. Five commercial wines (two reds, three whites) showed strong agreement between MP-AES, FAA, and ICP-OES, with concentration variances within 5%. The nitrogen plasma source delivered stable signals and minimized background emissions from residual organics.

Benefits and practical application of the method

• Lower operating costs by using in-house nitrogen generation instead of expensive or flammable gases.
• Enhanced safety and suitability for unattended or remote laboratory settings.
• Simplified multi-element analysis accelerates sample throughput during vintage monitoring.
• Wide linear dynamic range and improved detection limits support routine QA/QC and production control in wineries and testing labs.

Future trends and opportunities

Further development may extend MP-AES to additional trace elements and complex food or beverage matrices. Integration with automated sample handling and data management systems could enable real-time monitoring of metal levels in process streams. Portable or modular MP-AES instruments may facilitate on-site testing in vineyards and remote facilities, improving responsiveness during harvest seasons.

Conclusion

The Agilent 4100 MP-AES provides accurate, reliable determination of key metal ions in wine while offering significant operational advantages over FAA and ICP-OES. Its low cost of ownership, minimal infrastructure requirements, and safety profile make it an attractive choice for small to medium wineries and analytical laboratories.

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