Complex Matrices: Minimizing Lipids, Maximizing Recovery - Food Testing Application Compendium: Volume 3

Importance of the Topic

Food and environmental samples such as high-fat produce, dairy, meat, and animal feeds present major analytical challenges due to coextracted lipids and other matrix interferences. These interferences reduce method sensitivity, compromise chromatographic performance, increase instrument maintenance, and cause quantitation errors. Efficient, selective lipid removal is therefore critical to achieve low detection limits and reliable results for multiclass analytes—pesticides, veterinary drugs, mycotoxins, and polycyclic aromatic hydrocarbons (PAHs)—in complex matrices.

Aim and Overview

This compendium summarizes the development and validation of a unified sample preparation workflow for diverse applications in high-fat samples. Key objectives include:

• Demonstrate selective lipid removal without analyte loss using Agilent Enhanced Matrix Removal–Lipid (EMR–Lipid) sorbent.
• Apply QuEChERS or protein-precipitation extraction followed by EMR–Lipid dispersive SPE or Captiva EMR–Lipid cartridge cleanup.
• Achieve robust quantitation of multiclass analytes at regulatory levels via LC/MS/MS or GC/MS/MS.

Methods and Instrumentation

Sample preparation consisted of:

• QuEChERS extraction (acidified acetonitrile, water addition, salt partition).
• EMR–Lipid cleanup in dSPE tubes or pass-through cartridges activated with minimal water.
• Optional post-treatment (MgSO₄ phase separation or concentration step) to optimize sensitivity.

Instruments included ultrahigh-performance LC/MS/MS (Agilent 6490, 6460 or 6495 QQQ) and GC/MS/MS (Agilent 7000C, 5977), with optimized columns (Poroshell 120 EC-C18 or DB-5ms UI) and dynamic MRM/SIM acquisition.

Main Results and Discussion

Across multiple applications, EMR–Lipid cleanup provided superior matrix removal (50–95% co-extractives), reduced matrix effects, and sustained instrument performance over 100+ injections. Representative outcomes included:

• Multiclass pesticides in avocado by LC/MS/MS and GC/MS/MS: 44 pesticides, recoveries 60–110%, RSD <10%, limits of quantitation (LOQs) <1 ng/g.
• Veterinary drugs in bovine liver and beef: 30–39 drugs, recoveries 65–110%, RSD <10%, LOQs <2 ng/g.
• Macrolides in pork: 7 compounds, recoveries 75–100%, RSD <10%, LOQs <5 µg/kg.
• Mycotoxins in infant formula and cheese: 5–13 toxins, recoveries 85–115%, RSD <10%, LOQs <0.1 µg/kg.
• PAHs in salmon: 15 compounds, recoveries 65–110%, RSD <5%, LOQs <25 ng/g.

Selective lipid removal was confirmed by GC/MS full-scan, phospholipid monitoring, gravimetric residue analysis, and lipid freeze-out tests.

Benefits and Practical Applications

Implementing EMR–Lipid delivers:

• High analyte recoveries and precision in fatty matrices.
• Extended instrument uptime and decreased maintenance.
• Simplified workflows without specialized immunoaffinity or gel permeation cleanup.
• Compatibility with standard QuEChERS and LC/MS or GC/MS platforms.

This approach enables routine laboratories to achieve regulatory compliance for trace contaminants in challenging food and environmental samples.

Future Trends and Applications

Emerging directions include:

• Expansion to broader analyte classes (e.g., lipophilic toxins, emerging contaminants).
• Integration with automated sample preparation systems.
• Adaptation for high-throughput screening in food safety and environmental monitoring.
• Continued optimization for low-volume or minute samples (biological fluids, wildlife tissues).

Conclusion

Agilent EMR–Lipid technology represents a new generation of matrix cleanup that selectively removes lipids while preserving diverse analytes. Its application across multiple methods—LC and GC, multiclass and multicompound—demonstrates robust performance, ease of use, and significant time and cost savings. Laboratories analyzing high-fat samples will benefit from improved sensitivity, accuracy, and productivity.

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