HPLC ANALYSIS OF ISOPROTURON IN WATER USING ONLINE SAMPLE ENRICHMENT

Significance of the Topic

The presence of herbicide residues such as Isoproturon in soil and water poses significant environmental and public health concerns. Routine monitoring of such contaminants at trace levels is essential to ensure safe drinking water and protect ecosystems. Traditional offline cleanup techniques can be laborious and time-consuming, creating demand for automated, high-sensitivity analytical approaches.

Objectives and Study Overview

This study aimed to develop and validate an automated online enrichment HPLC method for selective and sensitive quantification of Isoproturon in environmental and drinking water samples. The workflow integrates sample pre-concentration, cleanup, separation, and UV detection to achieve performance comparable to LC-MS while maintaining simplicity and cost-effectiveness.

Methodology and Instrumentation

An Agilent 1260/1290 LC system was configured with a two-position, six-port switching valve for online trapping and elution. Key components included:

• Trap column: Poroshell 120 SB-Aq, 3.0 × 50 mm, 2.7 μm
• Analytical column: ZORBAX RRHD SB-C18, 3.0 × 100 mm, 1.8 μm
• Mobile phases: Milli-Q water (A) and acetonitrile (B)
• Diode array detector at 240 nm with 60 mm Max-Light flow cell
• Injection volume: 1000 μL, enrichment flow: 0.5 mL/min, analytical flow: 0.6 mL/min
• Software: OpenLAB ChemStation C.01.07

Online enrichment was performed by loading the sample onto the trap column in valve position 1, followed by switching to position 2 for elution onto the analytical column.

Main Results and Discussion

The method delivered a limit of detection (LOD) of 0.5 µg/L (S/N >3) and a limit of quantitation (LOQ) of 1.0 µg/L (S/N =10). Linearity was confirmed from 1 to 50 µg/L with a correlation coefficient (R²) of 0.999. Six replicate injections at 50 µg/L yielded retention time RSD of 0.10% and area RSD of 0.16%. Recovery studies in spiked tap water showed mean recoveries of 97.5% at 1 µg/L, 100.3% at 10 µg/L, and 99.98% at 50 µg/L, with an overall average of 99.2%.

Benefits and Practical Applications

This automated online enrichment HPLC-DAD strategy eliminates offline solid-phase extraction, reducing hands-on time and risk of contamination. It achieves sensitivity on par with LC-MS for routine environmental surveillance, regulatory compliance testing, and drinking water quality assurance. The robust, unattended operation enhances laboratory throughput and reliability.

Future Trends and Potential Applications

Emerging opportunities include coupling online enrichment with high-resolution mass spectrometry for multi-residue screening, development of miniaturized field-deployable systems for in situ monitoring, and integration with automated data analytics platforms. Further refinement of trap chemistries and pump designs may extend this approach to broader classes of polar and nonpolar contaminants.

Conclusion

The presented online enrichment HPLC-DAD method offers a rapid, sensitive, and reproducible solution for trace analysis of Isoproturon in water. By combining automated sample cleanup and high-efficiency chromatography, it meets stringent regulatory limits and streamlines routine analysis without sacrificing performance.

References

1. S. Kailasam, Trace Analysis of Chlorinated Herbicides in Water with Online Enrichment. A simple and rapid method with automated sample cleanup. Agilent Technologies publication 5990-6922EN, Nov 2012.