Techniques for Avoiding Unexpected Problems in LC and GC Analysis

Importance of the Topic

Sample matrices often contain particulates, lipids, salts, pigments and other interferences that compromise liquid and gas chromatography assays by causing peak distortion, ion suppression, increased backpressure, and instrument contamination. Effective sample preparation and cleanup are therefore essential to protect analytical systems, enhance method robustness, achieve accurate quantitation, and maintain high throughput across diverse applications in pharmaceuticals, food safety, environmental monitoring, and bioanalysis.

Study Objectives and Overview

This study surveys strategies for mitigating matrix-induced issues in LC and GC analysis by addressing both physical and chemical effects. Key goals include:

• Evaluating simple approaches such as dilute-and-shoot and filtration
• Comparing advanced sorbent technologies—including EMR-Lipid, Carbon S, PFAS WAX, and synthetic SLE media
• Demonstrating improvements in reproducibility, sensitivity, and throughput
• Outlining practical workflows for biofluids, food products, and environmental samples

Methodology and Instrumentation

A broad toolkit of sample cleanup techniques is presented:

• Physical filtration: syringe filters, filter vials and frits to remove particulates
• Dilute-and-shoot: minimal preparation for high throughput but limited cleanup
• Liquid/liquid extraction (LLE) and Supported Liquid Extraction (SLE) using Chem Elut S for consistent phase separation without emulsions
• Dispersive SPE (QuEChERS) with PSA, C18, Carbon S or GCB sorbents for rapid pigment, fat, and polar interference removal in food matrices
• Pass-through sorbent cleanup: Agilent Captiva EMR-Lipid, EMR-GPF/HCF for lipids and chlorophyll, plus Carbon S for pigments
• SPE platforms: polymeric HLB and Plexa phases, mixed-mode Ion exchange cartridges for broad analyte polarity and PFAS-specific WAX sorbents
• SPME fibers and Arrows for trace environmental and flavor analyses

Instrumentation spans LC, GC, LC/MS-MS (triple quadrupole), LC/Q-TOF, GC/MS/MS and ancillary equipment such as guard columns, autosamplers, vacuum manifolds, and positive-pressure processors.

Key Results and Discussion

Advanced cleanup approaches deliver substantial gains:

• EMR-Lipid sorbent removes >99% phospholipids from plasma, reducing ion suppression and lowering RSD from >25% to <3%
• Carbon S sorbent efficiently extracts pigments while preserving planar analytes, improving recovery and reproducibility in spice and produce matrices
• PFAS WAX cartridges provide clean blanks and consistent recoveries complying with EPA 533 and ISO 21675 methods
• SLE with synthetic Chem Elut S media achieves recoveries of 87–119% for aromatic amines with low RSD and eliminates emulsions
• SPE phases such as Bond Elut Plexa and HLB show broad analyte coverage from polar to nonpolar compounds
• QuEChERS workflows with customized dispersive kits streamline pesticide residue analysis in fruit, vegetables, and complex foods

Benefits and Practical Applications

• Enhanced data quality through reduced ghost peaks, stable retention times, and improved sensitivity
• Extended column lifetimes and reduced instrument maintenance by preventing build-up of matrix deposits
• Higher throughput using plate-based and pass-through formats for 96-well automation
• Flexible adaptation to diverse matrices including blood, urine, food oils, spices, dairy, environmental water, and solids
• Compatibility with regulated methods (EPA, AOAC, ISO) and straightforward method transfer

Future Trends and Applications

Emerging directions include:

• Integration of inline and automated sample cleanup to further reduce manual steps
• Development of tailored sorbents targeting new classes of analytes such as microplastics or polar emerging contaminants
• Combining machine learning with experimental design to optimize sample prep workflows
• Expansion of high-throughput, on-line SPE and dynamic extraction platforms for clinical and industrial monitoring

Conclusion

Effective sample preparation is a cornerstone of reliable LC and GC analyses. By selecting the appropriate cleanup strategy—ranging from simple filtration to advanced sorbent technologies—laboratories can achieve robust, reproducible, and sensitive assays while maximizing productivity and minimizing downtime.

References

1. Ucci A. Techniques for Avoiding Unexpected Problems in LC and GC Analysis. Agilent Technologies Application Note RA45194.6118634259, 2023.
2. Determination of 14 Polycyclic Aromatic Hydrocarbon Compounds in Edible Oil. Agilent Application Note 5994-1483EN.
3. Determination of UV Filters in Sunscreens Using Agilent Captiva EMR-Lipid Cleanup by HPLC. 5994-1611EN.
4. A Fast Sample Preparation Workflow for Veterinary Drugs Analysis in Salmon. 5994-1124EN.
5. Screening, Identification, and Quantitation of 102 Drugs in Human Whole Blood by LC/Q-TOF and LC-QQQ. 5994-2830EN.
6. Protein Precipitation for Biological Fluid Samples Using Agilent Captiva EMR-Lipid 96-Well Plates. 5991-9222EN.
7. Determination of Over 300 Pesticides in Cayenne Pepper. 5994-5630EN.
8. Pesticide Analysis of Peppers Using Captiva EMR-GPF Cleanup and LC/MS/MS or GC/MS/MS. 5994-4767EN.
9. Determination of Over 300 Pesticides in Tobacco Using Agilent Captiva EMR-LPD Passthrough Cleanup. 5994-5777EN.
10. Lipidomics Analysis of Human Plasma Using Agilent Bond Elut Lipid Extraction. 5994-3824EN.
11. Lipidomic Analysis of Human Plasma Using Bond Elut Lipid Extraction with LC/Q-TOF. 5994-1783EN.
12. Determination of Fat-Soluble Vitamins in Foods Using Agilent Chem Elut S Extraction with LC/DAD and LC/MS/MS. 5994-5063EN.
13. Drug of Abuse Analysis Using Agilent Chem Elut S Supported Liquid Extraction by LC/MS/MS. 5994-0950EN.
14. Quantitative Determination of a Panel of Endogenous Steroids in Human Serum by LC/MS/MS. 5994-0949EN.