Sample Clean-Up in the Fast Lane

Importance of the Topic

Efficient sample clean-up is critical in modern analytical chemistry to achieve high sensitivity, reduce matrix effects and protect expensive instrumentation. Lipids and proteins in complex biological and food matrices can cause ion suppression, contamination of ion sources and columns, and increase downtime for maintenance. Effective removal of these interferences enhances data quality and extends instrument lifetime.

Study Objectives and Overview

This compilation of Agilent application notes evaluates a new sorbent technology (Captiva EMR-Lipid) designed to remove both proteins and lipids in a single step. The work spans multiple use cases: analysis of pesticides in food, THC metabolites in plasma, abused drugs in blood, vitamin D analogs, veterinary drugs in meat, and mycotoxins in cheese. Each study demonstrates the performance of EMR-Lipid compared to conventional techniques.

Methodology and Instrumentation

Sample preparation workflows varied by matrix but shared a common EMR-Lipid pass-through format in 96-well plates or cartridges (1, 3 and 6 mL). Key steps included:

• Protein crash with organic solvent (ACN/MeOH) and centrifugation or positive pressure.
• Pass-through cleanup on EMR-Lipid sorbent exploiting size-exclusion and hydrophobic trapping of lipid chains.
• Optional second elution with 80:20 ACN/H₂O to maximize recovery.
• Evaporation and reconstitution prior to LC-MS/MS or GC-MS analysis.

Instrument platforms included Agilent LC systems with ZORBAX RRHD or Poroshell 120 EC-C18 columns, ESI-MS/MS (MRM detection), and GC-MS full-scan for food pesticide screening. Vacuum and positive-pressure manifolds facilitated high-throughput sample handling.

Key Results and Discussion

EMR-Lipid significantly reduced phospholipid and triglyceride signals (>99% removal), leading to:

• Dramatic drop in ion suppression and low RSD (<3%) for THC and vitamin D metabolites in plasma.
• Improved analyte recovery (80–110% across diverse drug classes) versus protein precipitation or QuEChERS alone.
• Cleaner GC inserts and LC sources after hundreds of injections, enabling shorter cycle times.
• Consistent detection of veterinary drugs (log P −1.5 to 5.5) in beef and pork with minimal method development.
• High recovery and reproducibility of mycotoxins in cheese matrices (RSD <10%, recoveries 85–110%) outperforming competitive sorbents.

Benefits and Practical Applications

The combined protein and lipid removal in one step delivers:

• Faster workflows with fewer centrifugation or filtration steps.
• Lower instrument maintenance and longer column lifetimes.
• High assay sensitivity and reproducibility across biological and food matrices.
• Flexibility for multi-residue screening of pesticides, drugs and toxins without extensive method revalidation.

Future Trends and Opportunities

As regulatory and research demands expand for multi-analyte profiling, robust clean-up technologies will become essential. Future developments may include:

• Integration of EMR-Lipid into automated platforms for 384-well formats.
• Customization of sorbent chemistries for specialized lipid classes.
• Combination with microflow LC-MS for ultra-high sensitivity bioanalysis.
• Application in clinical metabolomics to remove complex lipidome interferences.

Conclusion

Captiva EMR-Lipid provides a simple, one-step solution for simultaneous removal of proteins and lipids, delivering cleaner extracts, higher analyte recoveries and reduced instrument downtime. Its versatility across diverse matrices and analyte classes makes it a valuable tool for laboratories requiring high throughput and robust data quality.

Reference

• Agilent Application Note 5991-8636EN: THC Metabolite Analysis in Human Plasma
• Agilent Application Note 5991-7956EN: Vitamin D Metabolite Analysis
• Agilent Application Note 5991-8598EN: Multiclass Veterinary Drugs in Meat
• Agilent Application Note 5991-8694EN: Mycotoxin Analysis in Cheese