Reviewing Environmental Applications of Miniaturized Liquid Chromatography Systems

Scientists from the University of Valencia in Valencia, Spain published a review article on environmental applications of miniaturized liquid chromatography (LC) over the last 15 years in the Journal of Chromatography A.

Bottles check on the quality of the suspension. Quality Control Laboratory medicine. Chromatograph operation. | Image Credit: © neznamov1984 - stock.adobe.com

Miniaturized liquid chromatography (LC) has evolved thanks to work done in both industry and academia. The first commercialized miniaturized LC products launched in 1987. Since then, small LC systems have become indispensable tools for bioanalytical research. The miniaturization of LC is generally done to increase sensitivity, which is necessary in proteomics to detect low abundant peptides and proteins; other benefits can include improving the efficiency of interfacing with mass spectrometry and the reduction of solvent consumption (2). Liquid chromatography column miniaturization can overcome some challenges associated with traditional LC, Roxana Eggleston-Rangel of Phenomenex wrote previously in an article for LCGC (3). Reducing columns’ inner diameters reduces the amount of chromatography dilution, causing an increase in ion sensitivity and allowing for more efficient tandem mass spectrometry (MS/MS) sampling and more molecule identifications. Further, this approach holds higher signal-to-noise (S/N), lower limits of quantitation (LLOQ), and reduces solvent consumption, which reduces costs and benefits the environment (3). This technique is even more important with the widespread use of chemicals, which discharge into the environment and can be hazardous to human health, even at low concentrations.

Determining organic pollutants is an important research topic in environmental analytical chemistry. The production and consumption of chemicals has resulted in thousands of compounds being discharged into the environment, particularly causing contamination of water bodies, though these compounds can appear in soil, air, or biota. New techniques and methodologies are actively being developed to deal with this concern, with miniaturized LC emerging as a greener and more sensitive alternative to conventional LC (1). Advances in instrument miniaturization have also allowed portable LC instrumentation to be developed, which could become a promising tool for in-situ monitoring. In this study, the scientists reviewed the environmental applications of miniaturized LC over the last 15 years, all while showing different instrumentation, including off- and on-line pretreatment techniques, chromatographic conditions, and contributions to the environmental knowledge.

Miniaturized LC has shown itself in most applications to provide chromatographic separation with high efficiency and improved sensitivity compared to conventional LC. Additionally, lower flow rates greatly reduced the amount of mobile phase required per run, making the methodology greener and lowering costs. Further, on-line sample treatment, when performed, is often combined with miniaturized LC; this simplifies the sample preparation process while improving environmental analysis performance by carrying out the injection, extraction, preconcentration, separation, and detection in a single run. In this sense, column switching configurations based on trap columns with in-tube solid-phase microextraction (IT-SPME) were employed with good results, meeting the required limits of detection (LODs) set by legislation. As opposed to trap columns, which are tied more to C18 extractive phases, IT-SPME explores a more diverse number of phases, allowing it to be more selective in retaining the contaminants of interest.

Along with these developments, the miniaturization of LC instruments has introduced the development of portable environmental analysis systems. With the growing demand of instruments capable of in-situ analysis, portable LC has become a powerful tool for real-time monitoring of environmental samples. Miniature LC is believed to have a promising outcome in environmental analysis, showing a trajectory that aims for enhanced analytical capabilities, sustainability, greenness and portability.

References

(1) Cortés-Bautista, S.; Molins-Legua, C.; Campíns-Falcó, P. Miniaturized Liquid Chromatography in Environmental Analysis. A Review. J. Chromatogr. A 2024, 1730, 465101. DOI: 10.1016/j.chroma.2024.465101

(2) Sneekes, E-J.; Rieux, L.; Swart, R. Miniaturization of Liquid Chromatography: Why Do We Do It? Thermo Scientific 2013. https://assets.thermofisher.com/TFS-Assets/CMD/Reference-Materials/WP-70817-LC-Miniaturization-WP70817-EN.pdf (accessed 2024-7-10)

(3) Eggleston-Rangel, R. Why Use Miniaturized Columns in Liquid Chromatography? Benefits and Challenges. MJH Life Sciences 2021. https://www.chromatographyonline.com/view/why-use-miniaturized-columns-in-liquid-chromatography-benefits-and-challenges (accessed 2024-7-11)