SPE–LC–MS/MS Method for Emerging Contaminants in Water

Researchers from the University of Melbourne, University of Bisha, and the University of Gondar have developed and validated a liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for the determination of 39 emerging contaminants in water at ultra‑trace concentrations.¹ Published in the Journal of Chromatography A, the study reported a single analytical workflow capable of quantifying pharmaceuticals, pesticides, personal care products, and industrial chemicals across six water matrices, including bottled water, tap water, surface water, seawater, and wastewater influent and effluent.¹

Emerging contaminants such as pharmaceuticals, pesticides, and industrial chemicals are increasingly detected in water at nanogram‑per‑litre or lower concentrations, yet routine monitoring remains limited by analytical methods optimized for narrow chemical classes or single matrices. Many existing LC–MS workflows required large sample volumes, matrix-specific extraction protocols, or separate chromatographic methods for acidic, basic, and neutral compounds, making broad-spectrum surveillance resource-intensive and difficult to standardize. As regulatory and research frameworks increasingly emphasise mixture exposure and multi-class risk assessment, there is a need for a single, validated analytical approach capable of reliably quantifying chemically diverse contaminants across drinking water, natural waters, and wastewater at trace and ultra‑trace levels. This study addresses that need by developing and validating a solid-phase extraction (SPE)–LC–MS/MS method in which chromatographic conditions and sample preparation are aligned to maximize sensitivity, reproducibility, and applicability across multiple compound classes and water matrices.

Separate chromatographic conditions were applied for positive and negative electrospray ionization (ESI) modes to accommodate differences in analyte chemistry. In positive mode, mobile phases modified with formic acid were used to promote protonation and improve peak symmetry, while in negative mode, ammonium acetate buffers were employed to stabilize deprotonated species such as phenolic compounds and non‑steroidal anti‑inflammatory drugs.¹

Injection volume was evaluated as part of the chromatographic optimization. Small injection volumes (1–2 µL) were selected to minimize solvent‑strength mismatch and peak distortion, particularly for early‑eluting polar compounds. Gradient programs were designed to maintain chromatographic resolution while limiting total run times to approximately 10–13 minutes per polarity.¹

SPE was optimized alongside the LC method to ensure compatibility between sample preparation and chromatographic separation. A polymeric hydrophilic–lipophilic balanced (HLB) sorbent was selected following comparison with alternative materials. Elution was carried out sequentially using acetonitrile followed by methanol, reflecting their complementary abilities to disrupt hydrophobic and polar interactions, respectively.^2,3

Additional SPE parameters, including washing steps and solvent evaporation conditions, were evaluated to reduce matrix co‑extraction and analyte loss. A two‑step wash (water followed by 10% methanol in water) and evaporation at 35 °C with the addition of a water “keeper” were adopted to limit adsorption losses and matrix‑related variability, which are commonly observed in LC–ESI–MS workflows.^2,4

Under the optimized conditions, the method achieved instrument detection limits as low as 0.01 fg on‑column. Method detection limits ranged from 0.01 to 1.32 ng/L, with method quantitation limits between 0.03 and 3.96 ng/L, depending on compound and matrix.¹ For several pharmaceuticals and triazine herbicides, detection limits below 0.1 ng/L were reported.

Method validation indicated linear responses (R² > 0.99), recoveries predominantly within 70–130%, and intra‑ and inter‑day precision with relative standard deviations (RSD) at or below 20%, consistent with commonly applied acceptance criteria for multi‑residue methods, including those described in EPA Method 1694.^2,5 The method was based on a sample volume of 50 mL, which was smaller than that used in many previously reported workflows achieving comparable limits of detection.^6,7

The study illustrated how chromatographic parameters—including column selection, mobile‑phase composition, gradient design, and injection conditions—affected method performance in multi–class LC–MS/MS analysis. By aligning SPE and LC conditions, the authors demonstrated a workflow capable of accommodating a wide range of chemical properties and concentration levels across diverse water matrices.¹ Furthermore, evaluations using AGREE, MoGAPI, and BAGI indicated that the method achieves a balance between analytical performance and moderate environmental sustainability, while demonstrating high practical applicability, making it well-suited for routine, large-scale monitoring of emerging contaminants.¹

References

1. Weerasooriyagedara, M.; Partington, J. M.; Alghamdi, W.; et al. Development and Validation of a Multi‑Class SPE–LC–MS/MS Method for Emerging Contaminants in Water. J Chromatogr A 2026, 1768, 466655. DOI: 10.1016/j.chroma.2025.466655
2. Kadadou, D.; Tizani, L.; Alsafar, H.; Hasan, S. W. Analytical Methods for Determining Environmental Contaminants of Concern in Water and Wastewater. MethodsX 2024, 12, 102582. DOI: 10.1016/j.mex.2024.102582
3. Kravis, A.; Prosen, H. Exploration of Novel Solid-Phase Extraction Modes for Analysis of Multiclass Emerging Contaminants. Anal Chim Acta 2024, 1319, 342955. DOI: 10.1016/j.aca.2024.342955
4. Raposo, F.; Barceló, D. Challenges and Strategies of Matrix Effects Using Chromatography-Mass Spectrometry: An Overview from Research Versus Regulatory Viewpoints. TrAC 2021, 134, 116068. DOI: 10.1016/j.trac.2020.116068
5. USEPA, Method 1694: Pharmaceuticals and Personal Care Products in Water, Soil, Sediment, and Biosolids by HPLC/MS/MS, United States Environmental Protection Agency, 2007.
6. Anumol, T.; Merel, S.; Clarke, B. O.; Snyder, S. A. Ultra High Performance Liquid Chromatography Tandem Mass Spectrometry for Rapid Analysis of Trace Organic Contaminants in Water. Chemistry Central Journal 2013, 7, 104.
7. Ramadan, L.; Ozturk-Ufuk, I.; Yuksel, E.; Topuz, E. Development of LC–MS/MS Method for the Simultaneous Detection of Emerging Contaminants in Aquatic Matrices. Water Air Soil Pollut 2024, 235, 537. DOI: 10.1007/s11270-024-07342-8