Sensitive Detection of Trace Organic Contaminants in Water

Significance of the Topic

The widespread presence of pesticides, pharmaceuticals, personal care products and industrial chemicals in water sources poses significant risks to human health and ecosystems. Regulatory bodies worldwide, including the EU, US EPA and WHO, have set stringent limits at sub- to low ng/L levels. Conventional offline sample preparation for trace analysis is laborious, solvent-intensive and generates waste. Automated online solid phase extraction (SPE) coupled with modern triple quadrupole LC/MS offers a streamlined approach for rapid, sensitive quantification of trace organics in water.

Objectives and Study Overview

This study aimed to demonstrate the performance of Agilent’s 1290 Infinity FlexCube online SPE integrated with the Ultivo Triple Quadrupole LC/MS for detection of 51 trace organic contaminants in water. Key goals included achieving low-ng/L limits of quantification, robust linearity, fast polarity switching for positive and negative electrospray ionization and a total cycle time under 21 minutes without lengthy offline enrichment.

Methodology

• Large-volume injection of 900 µL water samples directly onto SPE cartridges
• Dynamic multiple reaction monitoring (dMRM) for simultaneous detection of pesticides, metabolites, pharmaceuticals, perfluorinated substances, hormones and plasticizers
• Calibration from 1.25 to 500 ng/L using 1/x weighted linear or quadratic fits where needed
• Signal-to-noise criteria (S/N ≥ 10) and accuracy (80–120 %) for limit of quantification determination

Used Instrumentation

• Agilent 1260 Infinity II Binary Pump and MultiSampler with 900 µL loop
• Agilent 1290 Infinity FlexCube online SPE module with dual PLRP-S trapping cartridges
• Agilent 1260 Infinity II Multi-Column Thermostat
• Agilent Ultivo Triple Quadrupole LC/MS with JetStream ESI source
• Agilent Poroshell 120 EC-C18 analytical column (3.0 × 50 mm, 2.7 µm)

Key Results and Discussion

• Linear calibration (R2 > 0.99) achieved for most compounds, with lowest point at 1.25 ng/L
• 86 % of analytes quantified accurately below 10 ng/L
• Precision (%RSD) < 20 % for all but one compound at the lowest level (n = 6)
• Fast polarity switching enabled simultaneous positive/negative mode detection of ~25 % of analytes
• Total enrichment and analysis cycle of 21 minutes versus hours for traditional offline SPE

Benefits and Practical Applications

• Reduced sample preparation time and labor through automated online SPE
• Lower solvent consumption and chemical waste
• High throughput with consistent cartridge performance and minimal user intervention
• Sensitivity and robustness suitable for regulatory monitoring of drinking and surface waters

Future Trends and Opportunities

• Integration with high-resolution MS for non-target screening and unknown identification
• Miniaturized or multiplexed SPE systems for higher throughput
• Advanced software for automated data processing and real-time reporting
• Expansion to emerging contaminants such as microplastics additives and novel PFAS

Conclusion

The Agilent 1290 Infinity FlexCube online SPE coupled with the Ultivo Triple Quadrupole LC/MS provides a powerful, rapid and sensitive workflow for trace organic contaminant analysis in water. The method achieves low-ng/L quantification, strong linearity and precision in a 21-minute cycle, delivering significant time, cost and solvent savings compared to offline SPE approaches.

References

1. European Union Drinking Water Directive 98/83/EC, European Commission, 1998.
2. EPA Method 540: Determination of Selected Organic Chemicals in Drinking Water by SPE and LC/MS/MS, US EPA.
3. EPA Method 1694: Pharmaceuticals and Personal Care Products by HPLC/MS/MS, US EPA, 2007.
4. WHO Guidelines for Drinking-Water Quality, 4th ed., World Health Organization, 2011.
5. Quantification of Trace‐Level Herbicides in Drinking Water by Online SPE and Triple Quadrupole MS, Agilent Technologies Application Note, 2013.
6. Comparison of Direct Injection and Online SPE for LC/MS Quantification of Trace-Level Herbicides, Agilent Technologies Technical Note, 2013.