Innovative Sample Preparation Strategies for Emerging Pollutants in Environmental Samples

Significance of the topic

Environmental sample preparation is a decisive step for reliable identification and quantification of emerging pollutants (notably microplastics and PFAS) across air, water and solid matrices. The increasing regulatory pressure and health/environmental concerns drive demand for methods that are more sensitive, selective, faster, field-deployable and environmentally sustainable. Improvements in sorbent chemistry, miniaturized extraction formats, and mobile sampling platforms expand the capacity to sample remote or hazardous sites and to reduce chemical and waste footprints while achieving ultratrace detection limits.

Objectives and overview of the review

The reviewed work (2019–2024) surveys recent trends in sample preparation for environmental analysis with emphasis on: (a) miniaturized extraction formats (SPE, SPME, MEPS, DLLME/LPME, MSPD), (b) advanced functional sorbents (MIPs, MOFs, COFs, ionic liquids, DES, LDHs, nano‑composites), and (c) innovative sampling formats and devices (3D-printed samplers, lab-in-a-bottle, drone/robot-mounted samplers, needle trap arrays). The goal is to highlight methodological advances, analytical performance gains, sustainability improvements, and remaining challenges for routine environmental monitoring of emerging contaminants.

Methodology and key approaches

• Miniaturized solid-phase methods: Cartridges, pipette-tip SPE, microextraction by packed sorbent (MEPS), spin columns and micro-SPE lower sample and solvent volumes while enabling automation and higher throughput.
• Solid-phase microextraction (SPME) family: traditional fibers, arrows, thin films and thin-film microextraction (TFME) are widely used for volatile/semivolatile organics and have been adapted for aqueous and solid matrices; variants include headspace, vacuum-, cooling-, ultrasound- and pressure-assisted SPME.
• Liquid microextraction techniques: dispersive liquid–liquid microextraction (DLLME) and switchable-solvent LPME deliver high preconcentration factors with minimal solvent use.
• Matrix solid-phase dispersion (MSPD) and related solid/semisolid workflows provide combined disruption, extraction and clean-up for soils, sediments and biota with reduced sample mass and solvent consumption.
• Needle trap devices (NTDs): packed-needle sorbents provide portable active or diffusive air sampling with fast thermal desorption to GC detectors; COFs and other high surface area sorbents improve capacity.
• Novel sorbent chemistries: molecularly imprinted polymers (MIPs), metal-organic frameworks (MOFs), covalent organic frameworks (COFs), aptamers, ionic liquids and deep eutectic solvents are optimized for selectivity and affinity to specific classes (PFAS, PAHs, pesticides, pharmaceuticals).
• Miniaturized, field-deployable samplers: 3D-printed pumps, drone-mounted SPME/TFME, lab-in-a-bottle paddle stirrers with MOF coatings and robotic samplers extend sampling to hazardous or remote environments and enable on-site preconcentration.
• Magnetic and density-based separations: magnetic levitation and magnet-assisted extraction are emerging options for separating microplastics by density/size and for concentrating microplastic-associated contaminants.
• Greenness assessment: methods increasingly report environmental metrics; tools such as AGREE are used to quantify method sustainability.

Used instrumentation

• Chromatography and mass spectrometry: GC–MS, GC–MS/MS, GC–FID, LC–MS/MS, UPLC–HRMS and portable GC–MS for on-site analysis.
• Direct ionization/ambient tools: DART-MS for rapid screening coupled with SPME/TFME sampling.
• Elemental detectors: ICP-MS and HR-CS graphite furnace molecular absorption spectrometry for trace metals.
• Spectroscopic and thermal tools: FTIR and µ-Raman for microplastic polymer ID; pyrolysis–GC–MS for compositional analysis of plastics and additives.
• Field platforms and devices: drone-mounted 3D-printed micropumps, lab-in-a-bottle stirrers with MOF-coated paddles, needle-trap arrays, robotic sampler platforms, and cryogenic air samplers.

Main results and discussion

• Analytical performance: Recent miniaturized workflows routinely achieve low ng L−1 to pg m−3 sensitivity for diverse analytes (PFAS, PAHs, pesticides, VOCs). Reported recoveries typically fall between ~70%–120% for validated methods, with LODs and LOQs tuned by sorbent choice and sampling geometry.
• Field deployability: Drone- and robot-based samplers (SPME/TFME arrays, 3D-printed micropumps) enable vertical and remote profiling (e.g., H2S, VOC plumes, deep-sea vents), reduce operator risk, and permit in situ preconcentration before transport to lab instruments or analysis with portable GC–MS.
• PFAS challenges and solutions: Ion-exchange-modified microextraction phases (HLB-WAX/PAN, weak anion exchange sorbents) and micro-SPE formats facilitate extraction of legacy and short-chain PFAS down to regulatory limits; direct SPME–MS (e.g., SPME–DART-MS) provides rapid screening but requires careful contamination control.
• Microplastics: Noninvasive density/flotation and spectroscopic screening (FTIR, µ-Raman) provide rapid occurrence data, while integrated approaches combining CA-SPME and pyrolysis–GC–MS quantify polymer mass and additives. Magnetic levitation and biphasic trapping allow sequential separation by density and size and simultaneous desorption of adsorbed organics.
• New sorbents: MOFs, COFs, MIPs, LDHs, CNT composites and nanoparticle-decorated phases increase selectivity and capacity. Tailored coatings (e.g., MOF-coated 3D-printed paddles) enable in situ extraction with good precision and low cost.
• Sustainability trends: Miniaturization, solventless techniques (SPME, TFME), greener solvents (ionic liquids, DES), re-usable sorbents, and open-source lab-in-a-bottle designs reduce waste and cost; AGREE-style metrics are being adopted to quantify improvements.
• Limitations and gaps: Heterogeneous solid matrices remain challenging for representativeness; PFAS ubiquity in laboratory materials complicates ultra-trace analysis; scaling lab prototypes to routine regulatory workflows and method harmonization/standardization remain outstanding needs.

Benefits and practical applications of advanced sample preparation

• Reduced sample/solvent consumption and chemical waste, improving laboratory sustainability and cost-efficiency.
• Enhanced selectivity and sensitivity through functional sorbents for targeted pollutants (PFAS, pesticides, pharmaceuticals, PAHs).
• Field-capable sampling and on-site preconcentration for rapid response (emergency monitoring, hard-to-access sites, deep sea, industrial emissions).
• Compatibility with high-throughput workflows and automation (spin columns, MEPS, 3D-printed cartridges), enabling routine environmental surveillance.
• Improved characterization of particulate-borne pollutants and microplastics through combined separation and thermal/spectroscopic analysis.

Future trends and opportunities

• Integration of portable mass spectrometers and rapid ambient ionization with miniaturized sampling (SPME–MS, TFME–portable GC–MS) for on-site, near real-time decision-making.
• Standardization and validation of miniaturized and field-deployable methods to meet regulatory requirements and interlaboratory comparability.
• Further development of selective, robust sorbents (engineered MOFs/COFs, MIPs, aptamer-functionalized materials) tailored to challenging analytes such as short-chain PFAS and metabolite/byproduct families.
• Expansion of additive manufacturing (3D printing) to produce low-cost, reproducible samplers and sorbent housings at scale.
• Wider adoption of green solvents (DES, biobased eluents) and lifecycle greenness metrics during method development.
• Advanced separations for microplastic sub-fractions (density/size multiplexing), improved coupling to chemical profiling (pyrolysis–GC–MS, LC–MS), and workflows for adsorbed pollutant desorption and analysis.
• Increased use of automation, robotics and remote sensing (drones, quadruped/robot samplers) for continuous environmental monitoring networks.
• Broader application of nontarget and suspect screening approaches integrated with improved sample preparation to map the environmental exposome more comprehensively.

Conclusion

Recent advances in sample preparation for environmental analysis demonstrate that miniaturization, new sorbent chemistries and mobile sampling platforms materially improve sensitivity, selectivity and sustainability. These innovations expand capabilities for monitoring emerging contaminants in complex matrices and enable field-deployable workflows. Remaining priorities are method standardization, contamination control for ultra-trace analytes (notably PFAS), and translation of promising prototypes into validated, routine monitoring tools.

Reference

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