Quantitative and Semi-Quantitative Determination of PPCPs and Their By-Products in Wastewater by Orbitrap MS

Significance of the Topic

Trace levels of pharmaceuticals and personal care products (PPCPs) in wastewater pose growing environmental and human-health concerns. Conventional treatment processes often fail to remove these micropollutants completely, leading to their release into surface and drinking water supplies. High-resolution mass spectrometry (HRMS) offers precise, accurate mass measurements and comprehensive screening capabilities that are critical for monitoring both parent PPCPs and their transformation by-products in complex wastewater matrices.

Study Objectives and Overview

This work aimed to develop and validate a quantitative and semi-quantitative workflow based on an Exactive Plus Orbitrap high-resolution mass spectrometer for the determination of 56 target PPCPs and for non-targeted screening of hundreds of related metabolites and by-products. A set of 35 permeate samples was collected from a pilot anaerobic membrane bioreactor (AnMBR) operated at three different temperatures (20 °C, 35 °C, 55 °C) over winter and summer periods to assess both seasonal and temperature influences on PPCP removal and by-product formation.

Methodology and Used Instrumentation

Samples were collected in amber bottles, stored at 4 °C, and processed within four weeks. A balanced hydrophilic-lipophilic SPE (200 mg, pH ~7) extracted analytes from 200 mL of permeate. Isotopically labeled surrogates (D- and 13C-labels) enabled isotope-dilution quantification. Calibration ranged from 2 to 100 ng/mL (level 1) with linearity r2 ≥ 0.999.

HPLC separation was performed on a Thermo Dionex UltiMate 3000 system:

• Positive-mode: C18 column (2.1×100 mm, 3 µm) with ammonium formate/formic acid and methanol/water gradients
• Negative-mode I and II: Hypersil GOLD C18 (2.1×100 mm, 3 µm) with acetonitrile/water and ammonium acetate buffers

An Exactive Plus hybrid quadrupole-Orbitrap MS with heated electrospray ionization acquired full-scan data (m/z 95–950) at 140,000 resolution (FWHM 200 m/z). TraceFinder software handled targeted quantification and non-targeted screening (database of 312 compounds) with a 5 ppm mass extraction window. Principal component analysis (PCA) and ChemSpider searches were performed in SIEVE software to assess treatment effects and discover unknown transformation products.

Main Results and Discussion

Quantitative analysis detected 43 PPCPs in >75% of samples, including caffeine, carbamazepine, DEET, lidocaine, lincomycin, ketoprofen, and bezafibrate. Median concentrations ranged from low ng/L to µg/L levels, with antibiotics generally at the lower end. PCA revealed that treatment temperature had a stronger influence on overall PPCP profiles than seasonal variation.

Semi-quantitative screening identified five triclosan (TCS) by-products (chlorophenols, methyl triclosan, chloro-triclosan isomers) and 16 carbamazepine (CBZ) transformation products. Relative abundances peaked at 35 °C, suggesting temperature-dependent degradation pathways. Microbial metabolism dominated triclocarban removal, while photodegradation and metabolic reactions contributed to TCS, diclofenac, and CBZ transformation.

Practical Benefits and Applications

• High-resolution full-scan HRMS enables simultaneous targeted quantification and retrospective non-targeted screening without method reconfiguration.
• Isotope-dilution improves accuracy and compensates for matrix effects in complex wastewater samples.
• Temperature and process monitoring data support optimization of bioreactor conditions to enhance PPCP removal.
• Workflow aligns with ISO-accredited SPE protocols (Method E3454) for regulatory and research laboratories.

Future Trends and Potential Applications

Advances in HRMS technology, such as faster scan speeds and real-time data processing, will expand non-target screening to thousands of compounds. Increasing availability of authentic transformation-product standards will improve semi-quantitative accuracy and identification confidence. Integration with multivariate statistical tools and machine-learning algorithms will facilitate predictive modeling of PPCP fate in treatment systems. Emerging applications include routine monitoring of novel contaminants, assessment of advanced oxidation processes, and coupling with bioassays to evaluate ecotoxicological impacts.

Conclusion

This study demonstrates a robust LC-Orbitrap MS approach for comprehensive detection of PPCPs and their by-products in wastewater permeates. The method delivers high sensitivity (ng/L detection limits), excellent linearity, and versatile screening capabilities. Temperature-driven trends in transformation pathways provide insights for reactor design and environmental risk assessment. Ongoing efforts to incorporate additional standards and expand non-target libraries will further enhance method scope and regulatory relevance.

References

1. Ternes TA, Joss A, Editors. Human Pharmaceuticals, Hormones and Fragrances: The Challenge of Micropollutants. IWA, 2006.
2. Kortenkamp A. Environmental Health Perspectives, 2007;115(Suppl 1):1–42.
3. Ontario Ministry of the Environment. Method E3454: Determination of Emerging Organic Pollutants in Environmental Matrices by LC-MS/MS.
4. Sanchez-Prado L, Llompart M, Lores M, García-Jares C, Bayona JM, Cela R. Photochemical Degradation of Triclosan in Wastewater by UV Light and Sunlight. Chemosphere, 2006;65(8):1338–1347.