Microwave Plasma Atomic Emission Spectroscopy (MP-AES) - Measuring metals in wine and food handbook

Importance of the Topic

Accurate measurement of metals in food, wine, soil and biological materials underpins public health, product quality and regulatory compliance. Modern laboratories demand analytical techniques that combine sensitivity, multi-element capability, speed, safety and low operating costs.

Objectives and Overview of the Study

This report introduces Agilent’s Microwave Plasma–Atomic Emission Spectroscopy (MP-AES) technology, compares it with conventional Flame Atomic Absorption Spectroscopy (FAAS) and Inductively Coupled Plasma–Optical Emission Spectroscopy (ICP-OES), and showcases method development and application examples across wine, foodstuffs, soils and plant tissues.

Methodology and Instrumentation

Agilent’s MP-AES uses a nitrogen plasma generated by a 2.45 GHz magnetron and air-extracted N₂ from a nitrogen generator. Key hardware includes a vertical torch, mass-flow-controlled nebulizer gas, concentrically baffled spray chamber, fast-scanning optics and CCD detector. Sample introduction is simplified using standard nebulization or specialized accessories (MSIS for hydride generation, EGCM for carbon removal, SPS autosamplers). MP Expert software automates wavelength selection, background correction and calibration.

Key Results and Discussion

MP-AES delivers sub-ppb detection limits for trace elements and linear dynamic ranges spanning parts-per-billion to percent levels. Comparative studies demonstrate excellent agreement with FAAS, ICP-OES and certified reference materials for:

• Total arsenic in California wines via hydride generation (MDL ~0.3 µg/L).
• Elemental profiling of Malbec wines for geographical origin using multivariate analysis.
• Routine multi-element assay of wine components (Ca, Fe, K, Mg, Mn, Na) without hazardous gases or burner changes.
• Micronutrient (Cu, Fe, Mn, Zn) determination in DTPA soil extracts with MDLs <0.1 mg/kg and excellent spike recoveries.
• Major element quantification in milk, rice flour and fruit juices with simple acid digestion or direct dilution.
• Analysis of aluminum in beverages, examining sugar and alcohol matrix effects and achieving recoveries within ±10%.
• Total metals in plant tissues and exchangeable cations in soils by single-step digestion or acetate extraction aligned with interlaboratory reference data.

Long-term stability tests over several hours show RSDs <3% for complex matrices. MP-AES also achieves significant cost savings versus FAAS by eliminating flammable gases and reducing cylinder handling.

Benefits and Practical Applications of the Method

• Lower cost of ownership via nitrogen plasma and on-site gas generation.
• Improved laboratory safety without acetylene or nitrous oxide.
• Unattended, high-throughput multi-element analysis.
• Wider dynamic range and superior detection for elements like P and B.
• Reduced sample preparation, no lamp or burner changes, and real-time interference correction.
• Flexibility for remote or decentralized labs enabling rapid environmental and quality testing.

Future Trends and Potential Applications

MP-AES is poised to support emerging demands in on-site testing, high-throughput screening, nutritional profiling, provenance verification, environmental monitoring and automated chemometric workflows. New accessories and software integrations will extend capabilities in trace gas analysis, vapor generation methods, and direct solid sampling.

Conclusion

Agilent’s MP-AES technology addresses modern analytical challenges by combining sensitivity, precision, multi-element throughput and low operational costs. It offers an ideal replacement for FAAS and a complementary choice to ICP-OES, empowering food, wine, agricultural and environmental laboratories to achieve reliable elemental insights.

References

• Tanabe et al., J. Anal. At. Spectrom, 2016: Total arsenic in wines by HG-MP-AES.
• Nelson et al., Am. J. Enol. Vitic., 2015: Elemental profiling of wines via MP-AES and chemometrics.
• Milestone Ethos HPR-FO-39: Rice flour digestion for metal analysis.
• Agilent 4100 MP-AES and 4210 MP-AES product literature.