Analyze Pesticides in Water with Stir Bar Sorptive Extraction and Thermal Separation

Multiple pesticides in water samples were successfully analyzed using an Agilent 5975T LTM GC/MSD equipped with an Agilent J&W DB-5ms Ultra Inert low thermal mass column module, with stir bar sorptive extraction and an Agilent Thermal Separation Probe for sample preparation. The method was simple, rapid, effective, and showed good linearity (R2 >0.9914) and high sensitivity for most of the target pesticides. Introduction An effective sample preparation and analysis method is required to monitor trace pesticide residues in environmental samples. For aqueous samples, conventional extractions require 1 to 2 L of water to obtain sufficient pesticide residue for analysis. Extraction and enrichment steps in these traditional sample preparation techniques are tedious, time consuming, labor intensive, and use large amounts of organic solvents. Stir bar sorptive extraction (SBSE) was introduced in 1999 as a solventless sample preparation method for the extraction and enrichment of organic compounds from aqueous matrixes [1]. The method is based on sorptive extraction, where the solutes are extracted into a polymer coating on a magnetic stirring rod. The extraction is controlled by the partitioning coefficient of the solutes between the polymer coating and the sample matrix, and by the phase ratio between the polymer coating and the sample volume. For a polydimethylsiloxane coating and aqueous samples, this partitioning coefficient resembles the octanol-water partitioning coefficient. The technique has been applied successfully to trace analysis in environmental, biomedical, and food applications [2,3,4].