Techniques for Avoiding Unexpected Problems in LC and GC Analysis

Importance of the Topic

Effective sample cleanup is essential to locate trace analytes within complex matrices and to protect chromatographic and mass spectrometric systems from contamination.
By removing proteins, lipids, salts and particulates, analysts achieve improved method robustness, lower detection limits, and reliable, reproducible data.

Objectives and Study Overview

This work outlines strategies for avoiding unexpected problems in liquid and gas chromatography arising from sample matrix effects.
The main goals are to compare offline and online cleanup techniques, to highlight physical and chemical matrix interferences, and to demonstrate the impact of tailored sample preparation on analytical performance.

Methodology and Used Instrumentation

Sample cleanup approaches presented include:

• Dilute-and-shoot and direct injection
• Mechanical filtration with syringe filters and filter vials
• Targeted filtration using Captiva EMR-Lipid for combined protein and lipid removal
• Supported Liquid Extraction (Chem Elut S) for LLE-like performance without emulsions
• QuEChERS extraction and dispersive SPE for food matrices
• Solid Phase Extraction (Bond Elut Silica, Plexa, mixed-mode sorbents)
• Solid Phase Microextraction (SPME fibers and arrows)
• Online SPE workflows with Flex Cube and in-line filters/guards

Instrumentation platforms include HPLC/UHPLC, GC, LC/MS and GC/MS(/MS), using techniques such as SIM and MRM to monitor performance under varying cleanup conditions.

Main Results and Discussion

Targeted cleanup with Captiva EMR-Lipid removed over 99% of phospholipids from plasma extracts, resulting in peak shape improvements and retention time stability.
Reproducibility improved from RSD > 25% with protein precipitation alone to RSD < 3% when combined with EMR-Lipid.
Supported Liquid Extraction (Chem Elut S) yielded recoveries of 87–119% for aromatic amines in 15 minutes hold time with RSD < 8.2%.
Online SPE configurations delivered high enrichment factors and minimized carry-over, while in-line filters and proper solvent handling prevented column fouling and mobile phase contamination.

Benefits and Practical Applications

Choosing the right cleanup method enhances throughput and lowers instrument downtime:

• Improved sensitivity through reduced ion suppression
• Extended column and inlet component lifetimes
• Reduced maintenance costs and frequency
• Compatibility with automated, high-throughput workflows
• Adaptability across diverse sample types, from biological fluids to food products

Future Trends and Opportunities

Advances in sorbent chemistry and monolithic supports will drive more selective cleanup with smaller footprints.
Integration of AI-guided method selection and robotic automation promises further gains in efficiency.
Development of greener solvents, miniaturized formats, and multi-dimensional workflows will broaden applications in environmental, clinical, and industrial analysis.

Conclusion

Robust sample preparation is the most reliable strategy to mitigate matrix-induced chromatography issues.
By aligning cleanup techniques—filtration, targeted sorbents, SLE, QuEChERS, SPE, and online enrichment—with sample characteristics, analysts can achieve high data quality, reproducibility, and instrument uptime.
Complementary practices such as in-line filters, proper solvent caps, and spring-activated fittings further safeguard system performance.

Reference

• Agilent Technologies. Determination of 14 Polycyclic Aromatic Hydrocarbon Compounds in Edible Oil. Application Note 5994-1483EN.
• Agilent Technologies. Determination of UV Filters in Sunscreens Using Captiva EMR-Lipid Cleanup by HPLC. Application Note 5994-1611EN.
• Agilent Technologies. A Fast Sample Preparation Workflow for Veterinary Drugs Analysis in Salmon. Application Note 5994-1124EN.
• Agilent Technologies. Analysis of Nitroimidazoles in Egg Using Agilent Captiva EMR-Lipid and LC/MS/MS. Application Note 5994-0641EN.
• Agilent Technologies. Mycotoxin Analysis in Peanut Butter Using Captiva EMR-Lipid Cleanup and LC/MS/MS. Application Note 5994-0366EN.