Enhanced Quantification of Emerging UV Filter Contaminants in Drinking Water Using Optimized LC-MS/MS Technique

Significance of the topic

Ultraviolet (UV) filter compounds used in sunscreens and personal care products are increasingly detected as trace contaminants in drinking water. Their environmental persistence and reported biological effects make sensitive and reliable monitoring essential for water quality assessment, regulatory surveillance, and risk evaluation. Analytical workflows that combine low limits of detection, robustness across diverse water matrices, and high throughput are therefore of practical importance for laboratories performing routine monitoring or research on emerging contaminants.

Objectives and overview of the study

This study aimed to develop and optimize a direct-injection LC–MS/MS method for the quantification of 20 commonly used UV filters in drinking water, targeting sub-ppt to high-ppb concentration ranges without offline extraction. Key goals included achieving excellent linearity and precision, demonstrating method robustness across multiple drinking water matrices, and validating that direct injection on a Shimadzu LCMS-8060RX triple quadrupole could deliver reliable quantification suitable for high-throughput monitoring.

Methodology

The method uses a Shimadzu LCMS-8060RX triple quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode. Most analytes were measured in positive ion mode, with benzophenone-4 analyzed in negative mode. Internal calibration curves were prepared in 60% methanol containing 0.1% formic acid, using at least seven calibrators per compound (replicated four times), covering a linear range from sub-ppt to high-ppb. Direct injection of 100 µL of sample was applied (no solid-phase extraction or other offline concentration). Method performance was assessed by analyzing fortified samples in five representative matrices (LC/MS reagent water, bottled water, filtered water, tap water, well water) in replicate (n = 5) and by analyzing unspiked field samples (n = 4).

Used instrumentation

• Mass spectrometer: Shimadzu LCMS-8060RX triple quadrupole.
• Analytical column: Shim-pack Velox biphenyl, 2.7 µm, 2.1 × 100 mm; delay column: Shim-pack Velox biphenyl, 2.7 µm, 2.1 × 50 mm.
• Injection volume: 100 µL (direct injection).
• Mobile phase/flow: 0.3 mL/min; gradient runtime 12 minutes (approx. 25–98% B).
• Gas parameters: nebulizing gas flow 4.0 L/min; heating & drying gas flow 10.0 L/min.
• Interface temperature: 300 °C; desolvation line temperature: 250 °C; heat block temperature: 400 °C.

Main results and discussion

The optimized method quantified 20 UV filter compounds with excellent analytical performance:

• Linearity: Calibration curves demonstrated R² > 0.99 for all targets across multi-decade ranges; representative calibration sets used up to 15 concentration points.
• Sensitivity: Direct injection of 100 µL enabled lower limits of quantification (LLOQs) in the sub-ppt range for the most sensitive analytes (reported LLOQs down to ~0.0005 ng/mL for select targets) and low ng/L (ppt) to high-ppb coverage for the full panel.
• Accuracy and precision: Calibrator accuracies were within 80–120% and intra-method %RSDs were <10% for calibrators and spikes.
• Matrix robustness: Fortified spikes across five matrices (LC/MS reagent water, bottled, filtered, tap, well) were quantifiable with mean recoveries 80–120% and %RSD <10%, indicating minimal detrimental matrix effects and suitability of the direct-injection approach for diverse drinking water types.
• Retention and chromatography: Retention times and peak shapes remained stable on the Shim-pack Velox biphenyl column throughout development; run time was 12 minutes enabling moderate throughput.

Representative chromatographic and calibration data included a spiked tap water chromatogram at 0.125 ng/mL and multi-point linear calibration plots, supporting the reported sensitivity and dynamic range. The panel covered common UV filters such as avobenzone (keto/enol isomers), several benzophenones (BP-1, BP-2, BP-3, BP-4, BP-6, BP-8, BP-10, BP-12), octocrylene, octisalate, homosalate, meradimate, and others, with retention times distributed roughly between ~2.8 and 6.0 minutes and linear ranges tailored per compound (from sub-ppt to 200 ng/mL depending on analyte).

Benefits and practical applications of the method

• Extraction-free workflow: Eliminates time-consuming sample preparation steps (e.g., SPE), reducing labor, solvent use, and potential analyte losses or variability.
• High sensitivity and wide dynamic range: Capable of detecting UV filters at environmentally relevant ng/L concentrations while maintaining quantification to higher levels when needed.
• Robustness across matrices: Demonstrated accurate recovery and precision in a variety of drinking water types, supporting routine monitoring and comparative studies.
• Throughput and simplicity: A 12-minute chromatographic cycle and direct injection facilitate higher sample throughput appropriate for monitoring programs.

Limitations and considerations

• Potential matrix effects: Although tested matrices showed acceptable performance, complex matrices (e.g., wastewater, highly organic waters) may still require cleanup or dilution to avoid ion suppression/enhancement.
• Method scope: The validated panel covers 20 UV filters; additional transformation products, metabolites or other emerging actives may require method extension or different ionization/fragmentation strategies.
• Regulatory and QA context: The method was developed for research use; implementation in regulated labs requires appropriate accreditation, additional QA/QC procedures, and availability of isotope-labeled surrogates for each target where possible.

Future trends and potential applications

Expected developments and applications building on this work include:

• Panel expansion: Inclusion of more UV filter transformation products, sulfonated/oxidized metabolites, and other personal care product markers to evaluate full exposure profiles.
• Isotope-labeled internal standards: Broader use of labeled surrogates to further reduce matrix bias and improve quantitative accuracy in diverse matrices.
• High-resolution mass spectrometry (HRMS): Complementary suspect and non-target screening to discover unknown degradation products and support source attribution.
• Passive or composite sampling integration: Coupling the sensitive direct-injection method with passive samplers or automated composite samplers for time-weighted monitoring.
• Automation and workflow scaling: Automated sample handling and data processing pipelines to increase throughput for large-scale monitoring efforts.
• Linking monitoring to treatment studies: Using the method to evaluate removal efficiencies in drinking water treatment trains and to assess formation/degradation pathways during treatment.

Conclusion

The optimized direct-injection LC–MS/MS method on the Shimadzu LCMS-8060RX delivers highly sensitive, precise, and robust quantification of 20 UV filter contaminants in drinking water without offline extraction. With sub-ppt to high-ppb capability, strong linearity (R² > 0.99), and robust recoveries (80–120% with %RSD <10%) across multiple water matrices, the workflow provides a practical high-throughput option for environmental monitoring and research into emerging UV filter contaminants. Adoption of isotope-labeled standards, method extension to additional analytes, and integration with HRMS screening are logical next steps to broaden applicability and improve trace-level confidence.

References

• Jaskulak et al. Current Environmental Health Reports, 2025, Vol. 12, No. 28.
• Shanthi et al. Photochemical & Photobiological Sciences, 2020, Vol. 19, No. 1.

Disclaimer

The method and instrumentation were developed by authors affiliated with Shimadzu Scientific Instruments. The presented applications are intended for Research Use Only (RUO) and are not for diagnostic procedures. The authors declared no competing financial interest in the original report.