Simultaneous Determination of Asulam, Thiophanate- Methyl, Siduron, Iprodione by Prominence-i

Importance of the Topic

Contamination of surface and drinking water by pesticide residues poses significant environmental and public health risks. In Japan, golf courses use a range of pesticides including asulam, thiophanate-methyl, siduron, and iprodione, often located near upstream water sources. Regulatory frameworks such as the 2003 Ministry of Health, Labour and Welfare Ordinance set stringent water quality criteria and require sensitive analytical methods to monitor these compounds at trace levels. This drives the need for robust high-performance liquid chromatography protocols capable of simultaneous multi-residue detection.

Objectives and Overview of the Study

This study evaluates a simultaneous HPLC method, compliant with the Japanese “Separate Method 9,” for quantifying four golf course pesticides. Key aims include verifying measurement accuracy, linearity, and repeatability after a 500-fold solid-phase extraction preconcentration step, ensuring detection down to 0.003 mg/L (0.002 mg/L for asulam).

Methodology and Instrumentation

The protocol combines sample concentration and chromatographic separation to achieve required sensitivity:

• Sample Preparation: 500× concentration via solid-phase extraction of test water, targeting 1.0–1.5 mg/L analyte solutions.
• Chromatography Conditions: Shim-pack VP-ODS column (150 mm × 4.6 mm I.D.), mobile phase of 50 mM KH2PO4 (pH 3.0) and acetonitrile (55:45, v/v), flow rate 1.0 mL/min, column temperature 40 °C, injection volume 10 µL.
• Detection: Dual-wavelength UV monitoring at 270 nm for asulam and 230 nm for thiophanate-methyl, siduron, and iprodione using a Prominence-i HPLC system.

Instrumentation Used

The analysis was performed on a Shimadzu Prominence-i integrated HPLC platform, equipped with:

• Shim-pack VP-ODS analytical column.
• UV–Vis detector capable of dual-wavelength monitoring.
• High-precision pump and autosampler module for consistent flow and injection reproducibility.

Main Results and Discussion

Chromatographic separation achieved baseline resolution for all four pesticides in under 8 minutes at sensitivity levels of one-hundredth of target concentrations. Calibration curves spanning 0.08–5 mg/L yielded exceptional linearity (R2>0.9999) for each analyte, with siduron quantified by summing its two peaks. Repeatability studies demonstrated retention time RSDs <0.04% and peak area RSDs <0.5% at regulatory target levels, and <3.7% at 0.08 mg/L (n=6), confirming robust precision at trace concentrations.

Benefits and Practical Applications

The validated method enables:

• Routine monitoring of pesticide residues in environmental water to comply with national regulations.
• High-throughput analysis in QA/QC laboratories due to rapid run times and minimal interference.
• Adaptability for multi-residue screening by adjusting detection wavelengths and gradient profiles.

Future Trends and Potential Uses

Emerging trends include coupling HPLC to high-resolution mass spectrometry for enhanced selectivity and identification, development of automated sample preparation workflows to further reduce detection limits, and expansion of multi-residue panels to encompass new generation agrochemicals. Integration of online SPE and advanced data analytics will further streamline environmental pesticide surveillance.

Conclusion

The presented Prominence-i HPLC method delivers rapid, sensitive, and reproducible simultaneous determination of asulam, thiophanate-methyl, siduron, and iprodione in water samples. It meets stringent Japanese water quality requirements and offers a robust tool for environmental monitoring and regulatory compliance.

Reference

Shimadzu Application News L480: Simultaneous Determination of Asulam, Thiophanate-Methyl, Siduron, Iprodione by Prominence-i, First Edition Jan. 2015.