The Measure of Purity - Water quality applications

Significance of the Topic

Water is the foundation of ecosystems, agriculture, industry, and human health. Contamination by volatile and semivolatile organics, pesticides, pharmaceuticals, per- and polyfluoroalkyl substances (PFAS), endocrine disruptors, trace metals, and emerging nanoparticles poses growing risks. Regulatory bodies worldwide mandate frequent monitoring to prevent acute and chronic exposure, driving demand for sensitive, robust, and high-throughput analytical solutions.

Objectives and Overview of the Study

This whitepaper evaluates a comprehensive workflow for water quality analysis, detailing methods that span headspace and purge-and-trap GC, single- and triple-quadrupole GC/MS, LC/MS with online SPE, high-resolution Q-TOF, UV-Vis, AAS, ICP-OES, ICP-MS, and MP-AES. Agilent Technologies’ products and strategies are reviewed for achieving low detection limits, minimal matrix interference, and regulatory compliance across organic and inorganic classes.

Methodology

Sampling and Preparation

• Headspace extraction and salt addition to isolate VOCs prior to GC/MS analysis in SIM/SCAN mode, achieving parts-per-trillion detection.
• Helium or nitrogen purge-and-trap concentrators for volatiles in drinking water (US EPA Method 524.2), coupled to GC/MS with Ultra Inert columns for low-ppt sensitivity.
• SPE using Bond Elut SAX sorbents for haloacetic acids, followed by derivatization and GC/µECD on dual UI columns for sub-ng/mL quantitation.
• Online SPE enrichment of trace herbicides into triple-quadrupole LC/MS for LOQs down to 1 ng/L, featuring dynamic MRM with a 700+-compound pesticide library.
• Direct aqueous injection LC/MS/MS of pharmaceuticals in surface water at low‐ppt levels.
• Single-particle ICP-MS for titanium dioxide and zinc oxide nanoparticle sizing and quantitation in pool water.

Separation and Detection

• GC/MSD with 7697A headspace sampler and 8890 GC for EU and US EPA VOC regulations, showing <0.10 ppb detection limits across 60 compounds.
• 7000D triple-quadrupole GC/MS at elevated quadrupole temperatures to maintain performance with semivolatiles, pesticides, PAHs, and PBDEs in wastewater without cleanup.
• LC/Q-TOF for non-target screening of PPCPs and PFAS, providing sub-ppm mass accuracy, isotopic fidelity, and five orders of dynamic range.
• Agilent 280Z Zeeman GFAA and VGA-77 cold-vapor AAS for mercury and other trace metals per US EPA Method 245.1 and 200.9.
• 5110 SVDV ICP-OES for simultaneous axial and radial readings of 26 elements in certified reference water with 90–109% recovery.
• 7800 and 7900 ICP-MS with ISIS 3 and high-matrix introduction for rapid trace element analysis, meeting US EPA Method 200.8 with recoveries of 90–108%.

Instrumentation Used

• Agilent 7697A Headspace Sampler; 8890 GC and 5977B/7000D GC/TQ/MSD systems
• Teledyne Tekmar Lumin P&T, AQUATek LVA, Atomx XYZ autosamplers
• Agilent 1290 Infinity II LC and Flexible Cube with 6400, 6470, 6490, and Ultivo triple-quadrupole LC/MS
• Agilent 7250 GC/Q-TOF and 6500 LC/Q-TOF accurate-mass systems
• Agilent 280Z Zeeman GFAAS and 240 Series AA with VGA 77
• Agilent 5110 SVDV ICP-OES; 7800 and 7900 ICP-MS; 4210 MP-AES
• Bond Elut SPE cartridges and Agilent J&W UI columns (DB-35ms, DB-624 UI, DB-XLB); InfinityLab Poroshell 120 columns
• Cary 60 UV-Vis with fiber-optic dip probe; Gas Clean gas purifiers and regulators

Main Results and Discussion

VOCs and semivolatiles were quantified below regulatory thresholds, with GC/MS pub-level detection limits of 0.05–0.10 ppb and ppt-level capability using headspace SIM. P&T methods delivered low-ppt to ppq sensitivity and <20% RSD for 71 volatiles in 15 min runs. SPE-GC/ECD achieved 0.05–0.5 ng/mL HAA detection with 82–117% recoveries. Triple-quadrupole LC/MS coupled with online SPE yielded herbicide LOQs of 1–5 ng/L, recoveries >80%, and robust tMRM screening at 100 ppt. Emerging contaminants (PPCPs, PFAS) were detected at 10 ng/L and 25 pg on-column with high linearity and low background. Inorganic analyses (AAS, ICP-OES, ICP-MS) matched certified values (90–109% recovery), covered % levels to ppt, and included nanoparticle characterization in real-world samples.

Benefits and Practical Applications of the Method

• Full regulatory compliance across US EPA and EU directives for drinking and wastewater.
• High throughput via headspace, P&T, and online SPE automation.
• Matrix-tolerant technologies (Inert flow path, HMI, DRS) for reliable trace analysis in complex samples.
• Flexible, scalable LC and GC column chemistries for fast method transfer and minimal startup time.
• Comprehensive data software (MassHunter, TekLink, CrossLab) for system monitoring, diagnostics, and streamlined reporting.
• Modular workflows from sampling to data audit trail, with 21 CFR Part 11 compliance options.

Future Trends and Possibilities of Use

Ongoing expansion of target lists to include emerging PFAS, microplastics, and novel drug residues will drive demand for sub-ppt detection. Integration of high-resolution MS with AI-based data mining will enhance non-target screening and structural elucidation. Miniaturized, field-deployable sensors and remote monitoring platforms may enable real-time water quality surveillance. Advances in sample prep automation and green solvents will further reduce analysis time and environmental impact.

Conclusion

Agilent’s integrated portfolio—spanning sample preparation, separation, detection, and informatics—addresses the full spectrum of water quality challenges. By combining robust hardware, inert flow paths, advanced chemistries, and compliant software, laboratories can achieve accurate, high-throughput, and reproducible analysis of organic and inorganic contaminants, safeguarding water resources and public health.