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

Importance of the Topic

The accurate determination of trace contaminants such as pesticides, veterinary drugs, mycotoxins, and polycyclic aromatic hydrocarbons (PAHs) in high-fat food matrices presents significant analytical challenges. Residual lipids co-extracted with target analytes cause chromatographic interferences, ion suppression, and instrument contamination, compromising sensitivity, precision, and instrument uptime.

Study Objectives and Overview

This series of application notes demonstrates the use of Agilent Enhanced Matrix Removal–Lipid (EMR–Lipid) dispersive and Captiva EMR–Lipid pass-through SPE sorbents to selectively remove lipids from complex food extracts while retaining diverse analyte classes. Combined with Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) or protein precipitation extraction workflows, these sorbents enable rapid cleanup and quantitation of multiclass analytes including pesticides, veterinary drugs, mycotoxins, and PAHs in matrices such as avocado, bovine liver, beef, pork, salmon, infant formula, and cheese.

Methodology and Instrumentation

• Extraction: QuEChERS AOAC or EN protocols or acidified acetonitrile protein precipitation.
• Cleanup: Agilent Bond Elut EMR–Lipid dispersive SPE or Captiva EMR–Lipid pass-through SPE cartridges with optional polish salts (MgSO₄/NaCl).
• Analysis: UHPLC-MS/MS on Agilent 6490/6495 QQQ or 1290 Infinity systems, and GC-SIM or GC-MS/MS on Agilent 7890/5977 and 7890/7000C systems. Columns: InfinityLab Poroshell 120 or J&W DB-5ms Ultra Inert.
• Quantitation: MassHunter software with isotopic internal standards and matrix-matched calibration.

Main Results and Discussion

• Pesticides in avocado (LC-MS/MS): 44 multiclass analytes at 5–200 ng/g, recoveries 70–120%, RSDs <10%, 71% lipid removal by weight.
• Pesticides in avocado (GC-MS/MS): 23 analytes at 50 ng/g, recoveries 70–120%, precision <15% over 100 injections, 95% cleanup efficiency.
• Veterinary drugs in bovine liver (LC-MS/MS): 30 analytes at 5–200 ng/g, recoveries 60–120%, precision <15%, 56% lipid removal.
• Veterinary drugs in beef (LC-MS/MS): 39 analytes at 1–1,000 ng/g, recoveries 70–120%, precision <10–20%, cleanup of 43–48% lipids by weight.
• Macrolides in pork (LC-MS/MS): 7 analytes at 10–100 µg/kg, recoveries 64–101%, RSDs <11%, LOQs <10 µg/kg.
• Aflatoxins in infant formula (LC-MS/MS): 5 analytes at 0.01–2.5 ng/mL, recoveries 88–113%, RSDs <14%, LOQs down to 0.01 ng/mL.
• Mycotoxins in cheese (LC-MS/MS): 13 analytes at 1–1,000 ng/g, recoveries 71–112%, RSDs <20%, cleanup 51–74% lipids by weight.
• PAHs in salmon (GC-SIM): 15 analytes at 25–500 ng/g, recoveries 62–98%, RSDs <5%, cleanup 48–51% lipids by weight.

Benefits and Practical Applications

• Highly selective lipid removal reduces matrix effects, improves sensitivity, and extends column and source life.
• Simple dispersive or pass-through cleanup fits into standard QuEChERS or protein precipitation workflows.
• Wide analyte scope enables multiclass, multiresidue analysis with a single preparation method.
• Formats for both high-throughput (3 mL dSPE) and large volume (6 mL cartridges) workflows.
• Easy implementation in regulated food testing laboratories with minimal training.

Future Trends and Potential Uses

Further development of EMR–Lipid cleanup is expected to support emerging high-resolution MS methods, automated robotic workflows, and new analyte classes such as lipophilic biomarkers and environmental pollutants. Buffered sorbent formulations and scale-up to 15 mL formats will broaden its applicability to more complex matrices and higher throughput settings.

Conclusion

EMR–Lipid technology provides a robust and efficient solution for lipid removal in complex food matrices, enabling accurate, precise, and sensitive analysis of multiclass residues. By integrating seamlessly into QuEChERS and protein precipitation workflows, it offers significant time savings and improved instrument uptime compared to traditional cleanup approaches.

Reference

• Anastassiades M. et al., “Fast and easy multiresidue method employing acetonitrile extraction/partitioning and dispersive solid-phase extraction,” J. AOAC Int. 2003, 86:412–431.
• Lehotay S. J. et al., “Use of buffering and other means to improve results of problematic pesticides,” J. AOAC Int. 2005, 88:615–629.
• Hildmann F. et al., “Pesticide residues in chicken eggs – A sample preparation methodology,” J. Chromatogr. A 2015, 1403:1–20.
• Anon., Commission Regulation (EC) No.1881/2006 and Guidance Document SANCO/12571/2013.