Excellent choices for food & agriculture applications

Importance of Food and Agricultural Analysis

Modern food safety and agricultural monitoring require sensitive, accurate measurement of trace and toxic elements—such as arsenic, cadmium, mercury, nickel, selenium, antimony, and heavy metals—in water, soils, crops, milk, shellfish, and processed beverages. Ensuring compliance with health regulations and protecting consumer health hinges on reliable detection of contaminants at sub-ppb to ppm levels.

Goals and Study Overview

This collection of application reports presents methods to:

• Quantify heavy metals in milk powder and liquid milk using direct ICP-OES without wet digestion or ashing.
• Measure cadmium, mercury, and nickel in biological tissues (shellfish) by atomic absorption (AAS) with cold-vapor and graphite furnace techniques.
• Determine methylmercury in tuna via speciated isotope dilution GC-MS.
• Assess toxic and nutritional trace elements in plant, soil, and distilled-spirit matrices by ICP-MS with collision/reaction cell (ORS), vapor generation, or standard AAS.
• Speciate and quantify arsenobetaine in fish using HPLC-ICP-MS for rapid screening.

Methodology and Instrumentation

• ICP-OES: Simultaneous and sequential axial ICP-OES (echelle polychromator with CCD) directly analyze raw milk powder solutions (2% w/v) for major, minor, and trace elements. Viscosity and ionization interferences are corrected via internal standards (Sc, Cs) and on-line Cs ionization suppression.
• Atomic Absorption: AAS with Zeeman background correction using pyrolytic platforms for Cd/Ni and VGA-76 cold-vapor for Hg. Sample digestion employs nitric acid and controlled microwave digestion, with gold addition to eliminate memory effects.
• HPLC-ICP-MS: Anion-exchange chromatography (isocratic NH4HCO3/tartaric acid +1% MeOH) coupled to ORS ICP-MS (He mode) for AsB, DMA, MMAA, and inorganic As in fish extracts. Spikes of 103Rh monitor drift; hydrogen mode enhances Se sensitivity.
• GC-MS Speciation: HS-SPME of Hg–CH3 derivatives followed by GC–EI–MS monitoring molecular ions of methylmercury isotopes for isotope-dilution quantitation, achieving <1% RSD and agreement with certified reference materials.
• ICP-MS Trace Analysis: High-throughput Agilent 7500cx with Octopole Reaction System in He or H2 mode removes Ar- and Cl-based interferences in whisky, soil, and plant digests. Automated sample introduction (ISIS) and dual vacuum pumps enable >12-hour runs with <2% drift.

Main Results and Discussion

• Milk Analyses: Direct ICP-OES quantitated major (Ca, K, Na, P, S) and trace elements (Ba, Fe, Mn, Zn) in milk powder and SRMs with <10% bias; He matrix tolerated 2% w/v solids without wet digestion.
• Shellfish Metals: Microwave-acid digests followed by Zeeman AAS yielded Cd, Ni, Hg in shellfish tissue with recoveries of 85–115% using gold washout and QC protocols.
• Arsenobetaine Speciation: HPLC-ICP-MS separated AsB, inorganic As, DMA, MMAA in 10 min; spike recoveries 97–105%; quantitation in CRMs and interlab study matched consensus values.
• Whisky Profiling: 7500cx provided sub-ppt DLs for Be, Cr, V, Se, and high-ppt quantitation of Pb from crystal decanters, demonstrating interference removal by He cell gas.
• Methylmercury in Tuna: GC-MS ID method achieved 0.7% RSD and certified value agreement (5.05 ± 0.04 vs 5.12 ± 0.16 µg/g) in BCR 464.

Benefits and Practical Applications

These methods deliver:

• High throughput: Automated extraction systems and 10–12 min runs enable large sample batches and unattended overnight operation.
• Robust interference control: Internal standards, collision/reaction cell technology, and gold washouts eliminate polyatomic and memory effects.
• Direct analysis: Minimizing hazardous reagents (perchloric acid), reducing prep time, and avoiding dilution for robust matrices.
• Speciation: Separation of toxic inorganic species from nutritional or non‐toxic organic forms in a single injection.
• Accurate quantitation: Isotope dilution, standard additions, and CRMs validate precision and trueness across techniques.

Future Trends and Possibilities

• Advanced cell chemistries: Reactive gases tailored for specific analytes (e.g. O2 for Se, NH3 for As) to further lower detection limits.
• Automated speciation platforms: Online coupling of sample prep, separation, and multi‐element detection for full speciation without manual steps.
• Miniaturized sensors and ambient MS: Portable or in-situ monitors for real-time field screening of environmental and food samples.
• High-resolution MS: Hybrid and time-of-flight technologies to resolve complex interferences and broaden speciation capabilities.

Conclusion

Comprehensive analytical approaches combining robust sample digestion, efficient interference removal, and sensitive multi‐element detection (ICP-OES, ICP-MS, AAS, GC-MS) enable accurate, high-throughput monitoring of toxic and nutritional elements in food and agricultural matrices. Method refinements—avoiding hazardous reagents, employing automated systems, and leveraging isotope dilution—ensure regulatory compliance and consumer safety.

References

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