Qualitative and Quantitative Analysis of Contaminants of Emerging Concern in Biosolids Using Dilute-and-Shoot UHPLC-Orbitrap MS Method

Importance of the Topic

Extraction and analysis of contaminants of emerging concern (CECs) in biosolids is vital for assessing environmental fate, regulatory compliance, and potential human and ecological exposure. High-resolution mass spectrometry offers comprehensive detection of parent compounds and transformation products at trace levels.

Objectives and Study Overview

This study aimed to develop a rapid dilute-and-shoot workflow using UHPLC coupled to Orbitrap MS for quantitative determination of 49 targeted CECs in biosolids and for screening 381 additional compounds, including pharmaceuticals, personal care products, musks, surfactants, and flame retardants.

Methodology and Instrumentation

Sample Preparation:

• Biosolids and biosolids-amended soil samples were dried, sieved (200 µm), and homogenized.
• Extraction employed ultrasonic shaking with two solvent cycles: solvent A (acetonitrile:0.1% acetic acid in water, 70:30 v/v, 1 mM EDTA) and solvent B (acetonitrile:acetone, 50:50 v/v) spiked with isotopically labeled surrogates.
• Supernatants were combined, centrifuged, evaporated to dryness, and reconstituted in internal standard solution prior to analysis.

Chromatography and Mass Spectrometry:

• Thermo Scientific Dionex UltiMate 3000 HPLC (binary pump, autosampler, column compartment) with Betasil and Hypersil Gold columns (2.1 × 100 mm) for positive and negative ion mode separations.
• Gradient elution in three methods covering different compound classes using formate- or acetate-based mobile phases.
• Thermo Scientific Exactive Plus Orbitrap MS with heated electrospray ionization (HESI), tuned and calibrated for full scan at 140 000 FWHM resolving power, AGC target 1 × 106, 100 ms injection time.

Data Processing:

• Quantitative analysis of 56 PPCPs via TraceFinder software using extracted ion chromatograms (5 ppm mass tolerance).
• Suspect screening of a 312-compound database and non-targeted identification via ChemSpider search through SIEVE software, based on accurate mass and isotopic pattern criteria.

Main Results and Discussion

Method Performance:

• Method detection limits ranged from low ng g−1 to sub-µg g−1 levels with recoveries of 56–140% and RSDs below 20% for most analytes.
• Acetonitrile/acetone extraction yielded similar recoveries to methanol-based solvents, facilitating solvent evaporation.

Quantitative Findings:

• All six biosolid samples contained bisphenol A, caffeine, carbamazepine, triclocarban, and triclosan in the high ppb range.
• Other analytes such as clofibric acid and DEET were also detected at variable concentrations across samples.

Semi-Quantitative Screening:

• Numerous artificial sweeteners, musks, quaternary ammonium surfactants, and organophosphorus flame retardants were identified, indicating widespread occurrence of diverse CECs and their by-products in biosolids.

Benefits and Practical Applications

This streamlined dilute-and-shoot UHPLC-Orbitrap MS method enables simultaneous quantitative and qualitative assessment of a broad range of CECs with minimal sample preparation, supporting high-throughput monitoring in environmental and regulatory laboratories.

Future Trends and Potential Applications

Expanding target lists, integration of suspect and non-target screening workflows, and coupling with in silico transformation prediction will enhance detection of emerging pollutants. The approach can be adapted for other complex matrices, including soils and plant tissues, to study bioavailability and ecological impacts.

Conclusion

The developed UHPLC-Orbitrap MS workflow provides robust, sensitive quantification and extensive screening of CECs in biosolids. Ongoing efforts focus on acquiring additional analytical standards and refining suspect identification to cover evolving contaminants.

Použitá instrumentace

• Thermo Scientific Dionex UltiMate 3000 HPLC system (HRG-3400RS pump, WPS-3000 autosampler, TCC-3400 column compartment)
• Thermo Scientific Betasil and Hypersil Gold columns (2.1 × 100 mm)
• Thermo Scientific Exactive Plus Orbitrap MS with HESI source
• Thermo Scientific Barnstead Nanopure water purification system
• Thermo Scientific TraceFinder and SIEVE software; ChemSpider database