Determination of aqueous chlorothalonil with solid-phase microextraction and gas chromatography

Area of Science:

• Environmental Chemistry
• Analytical Chemistry

Background:

• Chlorothalonil is a widely used fungicide, and its presence in water bodies necessitates reliable analytical methods for monitoring.
• Accurate quantification of chlorothalonil residuals is crucial for environmental protection and public health.

Purpose of the Study:

• To develop and optimize a solid-phase microextraction (SPME) method coupled with gas chromatography-electron capture detection (GC-ECD) for the analysis of chlorothalonil in aqueous samples.
• To investigate and optimize key parameters affecting SPME efficiency, including fiber type, temperature, salt addition, and absorption time.

Main Methods:

• Solid-phase microextraction (SPME) using a 100-microm polydimethylsiloxane fiber.
• Gas chromatography-electron capture detection (GC-ECD) for sensitive analyte detection.
• Optimization of extraction parameters (stirring rate, temperature, salt concentration, time) and thermal desorption conditions.

Main Results:

• Optimal extraction achieved with a 100-microm polydimethylsiloxane fiber, 40 min absorption, 1250 rpm stirring, room temperature, and high salt concentration.
• Optimal thermal desorption at 240°C for 3 min provided sensitive detection.
• Detection limits ranged from 2.86 µg/L (distilled water) to 9.23 µg/L (farm water).
• Relative standard deviations were generally below 3.0%, with good linearity (r=0.999) in the 5-200 µg/L range.

Conclusions:

• The proposed SPME-GC-ECD method is simple, rapid, and effective for analyzing chlorothalonil in diverse water matrices.
• Standard addition method is recommended to mitigate matrix interference and improve accuracy.
• The method is suitable for monitoring chlorothalonil contamination in environmental water samples.