The performance of sequential stir bar sorptive extraction (sequential SBSE) in combi- nation with thermal desorption (TD)-GC/MS for screening of pesticide residues in water was described.
The document details a method using sequential Stir Bar Sorptive Extraction (SBSE) coupled with Thermal Desorption (TD) and Retention Time Locked Gas Chromatography/Mass Spectrometry (RTL-GC/MS). This approach is designed to screen for organic pollutants, specifically pesticide residues, in water samples at ultra-trace levels. The method utilizes two stir bars sequentially: the first extracts without a modifier, while the second extracts after adding 30% NaCl to improve recovery of hydrophilic compounds.
The procedure involves performing an extraction on a 5-mL sample without a modifier using one stir bar, followed by a second extraction on the same sample after adding 30% NaCl using a second stir bar.
Both extractions are performed at room temperature (24 °C) for 60 minutes while stirring at 1500 rpm.
After extraction, the two stir bars are placed in a single glass desorption liner and thermally desorbed simultaneously.