Improved Persistent Organic Pollutants Analysis for a Safer Global Environment
TIMS could hold the key to sensitive detection of known and unknown POPs in food and water supplies
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Persistent organic pollutants (POPs) are toxic chemicals that threaten human health and cause environmental deterioration. The production and use of POPs peaked during the post-war industrial boom when they were a common byproduct of industrial manufacturing as well as an effective form of pest and disease control, with their aftereffects being felt ever since.
POPs present a particularly difficult challenge for two key reasons: they are resistant to degradation, and they are easily and rapidly dispersed and transported, mainly by wind and water. This makes POPs and their regulation very much a global issue.
International agreements, like the 2001 Stockholm Convention on Persistent Organic Pollutants,1 attempt to combat the adverse effects of POPs by regulating the production and use of these pollutants. However, their success is largely dependent upon current analytical methods for POPs, which have their limitations. This article highlights the potential of trapped ion mobility spectrometry (TIMS) for improved POPs analysis.
The pervading presence of POPs
Not only are POPs non-biodegradable but they also bioaccumulate and biomagnify, meaning POPs consumed by the lower echelons of the food chain are passed upwards from species to species, accumulating within the apex predator. This results in those at the top of the food chain, such as fish and humans, being more at risk. POPs enter the food chain through a range of environmental sources, including water, soil and industrial stack emissions in the air, which contaminate food webs and aquatic ecosystems. Consequently, more than 90% of human exposure to POPs such as dioxins, for example, is through food.2
Investigation into the effects of POPs on human health has shown that they have the potential to cause a number of health implications including cancer, neurobehavioral impairment, birth defects, immune system defects, learning disabilities, genotoxicity, endocrine disruption and reproductive disorders.3 It is therefore important that scientists collaborate with food manufacturers to monitor contamination in the food supply chain.
Per- and polyfluoroalkyl substances (PFAS) resist heat, water, oil and stains and are commonly used to create coatings on products such as food packaging, cookware, furniture, clothing and adhesives.4 Some of these substances have been classified as POPs because they bioaccumulate, do not biodegrade and are harmful to humans. The presence of PFAS in UK drinking water has recently come under scrutiny as it has been found that only 47 known PFAS are currently monitored, and that more than a third of water tested in England and Wales exceeded recommended limits.5 The 2020 European Union Directive coming into force in 2026 will enforce maximum limits for a total of 20 highest concern PFAS.6
However, regulatory bodies only suggest monitoring of known contaminants and consequently many POPs remain unidentified. As a result, there are possibly thousands of unregulated compounds synthesized by the chemical industry, including potential precursors and by-products that may give rise to even more harmful substances, about which there is limited knowledge. New POPs are constantly emerging as a result of chemicals breaking down in the environment and, as such, last year another three contaminants, Methoxychlor, Dechlorane Plus and UV-328, were added to the Stockholm Convention.7 It is therefore crucial that the testing of POPs becomes both more thorough and more widespread.
Existing POPs analysis
Targeted gas chromatography coupled with high-resolution mass spectrometry (GC-MS) is the most common method currently used to test for the presence of POPs. This technique is powerful and effective, but produces limited results as it only analyzes targeted compounds of interest. This means that many new emergent POPs are missed. It is therefore important that new methods are developed for both the monitoring of known POPs and the detection of emergent contaminants.
GC-MS has limitations beyond its failure to detect new contaminants. It also cannot provide a comprehensive analysis of complex environmental, food and human blood samples because such samples may contain other compounds that can interfere with accurate detection and quantification. Additionally, as many contaminants exist in extremely small quantities, often in sub-parts per trillion, their presence can sometimes be missed during testing. Consequently, more advanced equipment with higher specificity and sensitivity is required for the effective detection of POPs.
More sensitive methods for the detection of POPs
The integration of TIMS coupled with time-of-flight (TOF) is emerging as a powerful way to improve POPs testing. The combination of MS with TIMS-TOF technology provides fast and precise analysis of a broad range of contaminants, including those found in food products. Unlike current methods, TIMS-TOF offers the sensitivity to detect even the smallest trace amounts of known POPs, as well as the presence of new emergent contaminants, by providing a further degree of separation, which improves the accuracy and reliability of compound characterization. The speed of analysis is also enhanced as this method can simultaneously accumulate and concentrate ions of a given mass and mobility. This high sensitivity means TIMS-TOF can detect infinitesimal levels of POPs that conventional methods would not have the ability to identify as they are looking for known contaminants.
Various multi-residue analytical techniques have been developed, allowing for the improved detection of POPs exposure in agricultural supplies, food products and humans. TIMS-TOF supports the analysis of targeted POPs and the detection of novel, emergent POPs, allowing for a precise and extensive assessment of possible contaminant exposure.
Improved POPs analysis for a healthier future
With the presence of POPs increasing globally and the emergence of new contaminants, the need for improved POPs analysis and detection methods has never been greater. By continuously monitoring POPs and advancing analytical methods, researchers can not only prevent contaminants from entering food and water supplies, but can also reveal emergent POPs and advocate for their ban. Broadening global knowledge of POPs and their effects will help limit their impact on the environment and human health for a safer and more sustainable future.
1. U.S. Department of State. Stockholm Convention on persistent organic pollutants. Published January 5, 2021. Accessed March 4, 2024. https://www.state.gov/key-topics-office-of-environmental-quality-and-transboundary-issues/stockholm-convention-on-persistent-organic-pollutants/.
2. World Health Organization. Dioxins. Published November 29, 2023. Accessed March 4, 2024. https://www.who.int/news-room/fact-sheets/detail/dioxins-and-their-effects-on-human-health.
3. United Nations Environmental Programme. Why do persistent organic pollutants matter? Accessed March 4, 2024. https://www.unep.org/explore-topics/chemicals-waste/what-we-do/persistent-organic-pollutants/why-do-persistent-organic.
4. Centers for Disease Control and Prevention. Per- and polyfluorinated substances (PFAS) factsheet. Published May 2, 2022. Accessed March 4, 2024. https://www.cdc.gov/biomonitoring/PFAS_FactSheet.html.
5. Royal Society of Chemistry. Cleaning up UK drinking water. Published November 2023. Accessed March 4, 2024. https://www.rsc.org/policy-evidence-campaigns/environmental-sustainability/sustainability-reports-surveys-and-campaigns/cleaning-up-uk-drinking-water/.
6. European Union. Directive (EU) 2020/2184 of the European Parliament and of the council of 16 December 2020 on the quality of water intended for human consumption. Published December 23, 2020. Accessed March 4, 2024. https://eur-lex.europa.eu/eli/dir/2020/2184/oj.
7. Stockholm Convention. Information on the 16 chemicals added to the Stockholm Convention. Published May 12, 2023. Accessed March 4, 2024. https://www.pops.int/TheConvention/ThePOPs/TheNewPOPs/tabid/2511/Default.aspx.
About the authors
Gauthier Eppe is a full professor at the Université de Liège, Belgium, where he also holds the positions of director of the Mass Spectrometry Lab (MSLab) and director of the Molecular Systems (MolSys) Research Unit. Prof. Eppe started research in the field of contaminants over 20 years ago and has since worked in food safety, focusing on environmental contaminants’ entry into the food chain. He has contributed to the development of various multi-residue analytical techniques, encompassing exposure characterization from agricultural supplies, food products and human biomonitoring in biological fluids.
Dr Galvin obtained his PhD under the guidance of Prof. Howard Purnell at the University of Wales, Swansea and started his industrial career in Beecham Pharmaceutical R&D Department. Having used mass spectrometry substantially during his PhD, in 1985 he moved to a scientific instrumentation company with responsibility for the newly developed GC-ion trap detector. Further global career moves followed in sales before taking responsibility for business-focused groups targeting firstly proteomics and then food and environmental testing. He joined Bruker in 2012 as a director of sales before moving to executive management roles heading various global business groups focused on biopharmaceuticals, proteomics and latterly the applied markets.
