Trace contaminants challenge food laboratories as regulations tighten and matrices grow more complex. In a recent episode of Concentrating on Chromatography, produced in collaboration with Separation Science, host David Oliva spoke with Holly Lee, Staff Scientist, Food Market, Global Technical Marketing at Sciex, about how labs strengthen PFAS, mycotoxin, and emerging-contaminant workflows.
Experience That Shapes an Analytical Perspective
Lee began her career in government laboratories, where method validation and QA/QC shaped her approach to liquid chromatography mass spectrometry (LC-MS). That foundation guides her current work supporting scientists who face growing regulatory pressure and rapidly evolving contaminant classes. Analysts value her insight because she has dealt with the same challenges in routine workflows.
Ultra-Short-Chain PFAS and Chromatographic Limitations
Trifluoroacetic acid (TFA) and related ultra-short-chain PFAS create some of the most difficult chromatographic problems in food testing. These small, highly polar molecules show weak retention and distorted peak shapes on typical reversed-phase columns. They elute early with inorganic ions and other matrix components, thereby lowering accuracy due to ion suppression.
Lee stresses the need for careful column evaluation and gradient design to stabilize retention and sharpen separation. Her group screened diverse stationary phases and advanced methods using polar-selective C18 chemistries suited to these polar targets.
Background Contamination and Consumable Screening
TFA, perfluorobutanoic acid (PFBA), and other short-chain PFAS often appear in pipette tips, vials, solvents, and LC systems. Lee urged labs to screen every consumable, even when marketed as PFAS-tested. Pre-rinsing vials, flushing solvents through SPE cartridges, and monitoring blanks help reduce false positives. Some long-running LC systems, after years of flushing, show cleaner backgrounds than brand-new instruments.
Managing Matrix Interferences in Food Samples
Matrix interferences differ widely between commodities and even between samples of the same commodity. Lee highlighted the importance of strong chromatography and effective cleanup.
Solid-phase extraction (SPE) with purpose-built sorbents removes many early-eluting interferences before injection. Mobile-phase choices matter: methanol boosts PFAS response, while acetonitrile improves separation of PFOS and bile-acid interferences common in seafood and eggs. High-resolution mass spectrometry sharpens specificity by using narrow extraction windows to isolate exact masses.
Publicly available interference databases also help analysts identify known coeluting species before they commit time to deeper investigations.
Masked Mycotoxins and Analytical Blind Spots
Plants metabolize parent mycotoxins into conjugated forms. These modified toxins can revert to the toxic form during digestion. They remain unregulated, and analytical standards are available for only a subset. Exposure is still poorly understood.
Lee sees an urgent need for sensitive LC-MS workflows that quantify known toxins and screen for unknown derivatives within a single method.
Sensitivity Requirements for Regulated Mycotoxins
Many regions set limits in the sub- to low-ppb range, with stricter requirements for foods consumed by young children. Achieving these LOQs demands strong ionization efficiency, stable chromatography, and optimized cleanup strategies.
Where LC–MS Fits Within Broader Analytical Toolkits
For microplastics, Lee notes that Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, pyrolysis gas chromatography-mass spectrometry (GC-MS), and high-resolution mass spectrometry (HRMS) each provide different forms of structural and compositional insight. Recent research shows LC-MS can characterize nanoscale polymer fragments and degradation products when particles shrink beyond optical detection limits. LC-MS also supports studies on sorption and desorption behavior to assess whether microplastics act as sinks or carriers for environmental contaminants.
Improving Workflow Efficiency Across the Laboratory
Lee encourages labs to simplify sample preparation whenever instrument sensitivity allows. Direct injection or dilution reduces turnaround time, lowers contamination risk, and cuts solvent use.
Automation is gaining traction across SPE, dilution, solvent handling, and standard preparation. Automated workflows improve reproducibility and free scientists to focus on data review and troubleshooting. Lee also points out that many LC-MS software platforms contain underused features (such as automated optimization, queue management, batch processing, and integrated quantitation tools) that shorten analysis time when applied effectively.
Future Directions: Sustainability and Creative Chromatography
Lee expects sustainability to influence method development across food testing. Miniaturized extraction, micro-SPE formats, and solvent-reduction strategies now dominate discussions at major residue-analysis conferences.
She also sees value in creative approaches to column chemistry. Her group has explored combining HILIC and C18 columns to broaden selectivity for wide PFAS panels. Strong partnerships between instrument and column developers will continue to drive new solutions for complex food matrices.
Explore Additional Resources
Learn More:
- Visit the Sciex website for information on food and beverage testing solutions.
- Explore the Concentrating On Chromatography podcast to dive into the frontiers of chromatography, mass spectrometry, and sample preparation with host David Oliva.
Connect with Holly:
- LinkedIn: Holly Lee
