USDA Scientists Explore Centrifuge-Based SPE for Cleanup in High-Throughput Food Analysis
Nicolás Michlig and Steven Lehotay of the United States Department of Agriculture recently tested centrifuge-based solid-phase extraction (SPE) for cleanup in high-throughput analysis of chemical contaminants in foodstuffs. Their findings were published in the Journal of Chromatography A (1).
Washington, DC, USA - June 22, 2022: The United States Department of Agriculture (USDA) Headquarters complex in Washington, DC. | Image Credit: © Tada Images - stock.adobe.com
Quick, easy, cheap, effective, rugged, and safe (QuEChERS) methods, first created for extracting multi-class pesticide residues from fruits and vegetables, have proven useful in sample preparation since inception (2). QuEChERS has proven simultaneously applicable to environmental contaminants, mycotoxins, and other applications. However, it was first developed when technology did not achieve as low detection limits and broad scope of analysis as currently possible using modern gas and liquid chromatography (GC and LC) and mass spectrometry (MS) instruments.
QuEChERS has evolved with further research, and the “quick, easy, cheap, effective, rugged, safe, efficient, and robust” (QuEChERSER) mega-method was developed in 2021. QuEChERSER has been praised for having a broader scope than QuEChERS, as it can include a wider range of pesticides, veterinary drugs, and environmental and other types of contaminants, as well as perfluorinated compounds. Additionally, QuEChERSER involves improved cleanup for gas chromatography–mass spectrometry (GC–MS) analysis through miniaturized solid-phase extraction (µ-SPE), as opposed to dispersive solid-phase extraction (d-SPE) commonly used in QuEChERS.
In this study, the researchers created a new approach using centrifugal µ-SPE as a simpler and lower-cost alternative using the same commercial mini-cartridges as the robotic version. Both robotic and centrifugal µ-SPE were compared for the cleanup of QuEChERS and QuEChERSER extracts of 10 commodities (avocado, blueberry, egg, mixed grains, honey, bovine kidney/liver, whole milk, black olive, spinach, and tilapia) in the low-pressure GC–tandem MS (GC–MS/MS) analysis of 245 pesticides and environmental contaminants.
In most cases, the QuEChERS extracts overwhelmed the sorbents in the mini cartridges, this led to less cleanup and worse performance in the most complex matrices. The QuEChERSER extractions, which were 4-fold and more diluted, did not have this issue, and was still able to meet the detection limit.
Graphitized carbon black (GCB), which is a widely used SPE sorbent in the food and environmental testing industries, proved unnecessary for cleaning samples that did not contain chlorophyll, with the inclusion of over 1 mg of GCB in mini-cartridges leading to <3% recovery of certain structurally planar analytes (3). In QuEChERSER, analyte recoveries averaged 99% in all matrices using robotic and centrifugal µ-SPE, though robotic liquid handling demonstrate4d better precision of 4% relative standard deviation (RSD) compared to 6% when the centrifugal option was used. Cleanup was also slightly better using robotic automation.
According to the scientists, QuEChERS using d-SPE cleanup was made to achieve “just enough” selectivity for streamlined sample preparation using MS-based detection; it was not intended for highly complex matrices (1,4). QuEChERSER extraction seems to overcome the problems that come with QuEChERS, with µ-SPE being demonstrated to provide more optimal cleanup and analytical performance than d-SPE. Even if only pesticides are analyzed, QuEChERSER using modern analytical instruments can better meet needs for a wide array of complex foods compared to QuEChERS.
References
(1) Michlig, N.; Lehotay, S. J. Use of a Centrifuge in Solid-Phase Extraction is a Valid Platform for Cleanup in the High-Throughput Analysis of Chemical Contaminants in Nonfatty and Fatty Foods. J. Chromatogr. A 2025, 1749, 465882. DOI: 10.1016/j.chroma.2025.465882
(2) González-Curbelo, M. Á.; Socas-Rodríguez, B.; Herrera-Herrera, A. V.; et al. Evolution and Applications of the QuEChERS Method. TrAC Trends Anal. Chem. 2015, 71, 169–185. DOI: 10.1016/j.trac.2015.04.012
(3) Science Unfiltered. Graphitized Carbon Black and How It Will Improve Your Lab Functionality. Phenomenex 2018. https://phenomenex.blog/2018/08/21/graphitized-carbon-black/ (accessed 2025-3-25)
(4) Anastassiades, M.; Lehotay, S. J.; Štajnbaher, D.; Schenck, F. J. Fast and Easy Multiresidue Method Employing Acetonitrile Extraction/Partitioning and “Dispersive Solid-Phase Extraction” for the Determination of Pesticide Residues in Produce. J. AOAC INT. 2003, 86 (2), 412–431. DOI: 10.1093/jaoac/86.2.412
Analytical Challenges in Measuring Migration from Food Contact Materials
November 2nd 2015Food contact materials contain low molecular weight additives and processing aids which can migrate into foods leading to trace levels of contamination. Food safety is ensured through regulations, comprising compositional controls and migration limits, which present a significant analytical challenge to the food industry to ensure compliance and demonstrate due diligence. Of the various analytical approaches, LC-MS/MS has proved to be an essential tool in monitoring migration of target compounds into foods, and more sophisticated approaches such as LC-high resolution MS (Orbitrap) are being increasingly used for untargeted analysis to monitor non-intentionally added substances. This podcast will provide an overview to this area, illustrated with various applications showing current approaches being employed.
