Development of a solventless stir bar sorptive extraction/thermal desorption large volume injection capillary gas chromatographic-mass spectrometric method for ultra-trace determination of pyrethroids pesticides in river and tap water samples

Abstract

Stir bar sorptive extraction (SBSE) has been developed in 1999 to efficiently extract and preconcentrate volatile compounds, and many applications have been found after that. This technique conforms to the principles of green chemistry. Here, we used an autosampler with an online thermal desorption unit connected to CGC-MS to analyze pesticides. This study describes the development of a highly sensitive extraction method based on SBSE for simultaneous determination of ultra-trace amounts of four pesticides λ-cyhalothrin, α-cypermethrin, tefluthrin, and dimefluthrin in environmental water samples. This method was compared to the standard liquid–liquid extraction. In this study, a totally solventless SBSE was applied to river and tap water samples for the extraction and preconcentration of four pesticides. PDMS-coated SBSEs of 10 mm × 1 mm thickness were used for this purpose, and SBSEs were directly placed into a large-volume injector of a CGC-MS for thermal desorption of the analytes. In all extractions, deltamethrin was used as an internal standard. This method showed linearity in the range of 1.0–200.0 ng L−1 for cyhalothrin, tefluthrin, and dimefluthrin and 10.0–800 ng L−1 for cypermethrin. Preconcentration factors of 179, 7, 162, and 166 were obtained with very low limits of detection of 0.32, 3.41, 0.36m and 0.69 ng L−1 for cyhalothrin, cypermethrin, tefluthrinm and dimefluthrin, respectively. These detection limits are thousands of times lower than that of the standard method of liquid–liquid extraction. Reproducibility of the method, based on the relative standard deviation, was better than 7.5% and recoveries for spiked tap and river water samples was within the range of 87.83–114.45%. The application of PDMS-coated SBSE coupled with CGC-MS equipped with a large volume injector thermal desorption unit can be used for ultra-trace analysis of environmental water samples. Solventless SBSE offers several advantages over conventional traditional liquid–liquid extraction such as being very fast and economical and provides better extraction without requiring any solvents; so it can be considered as a green method for the analysis of pesticides.

Deep Eutectic Solvent Stir Bar Sorptive Extraction: A Rapid Microextraction Technique for the Determination of Vitamin D3 by Spectrophotometry

“…Among other advantages, using viscous phases has the advantage of several orders of magnitude higher diffusion coefficients of the analytes than that of solid coatings; so, higher adsorption occurs for this type of coatings, including polymers. A stir bar with poly­(dimethylsiloxane) coating is the most applied (polymeric) phase and is sold commercially under the trademark of Twister by GERSTEL GmbH & Co KG (Mülheim, Germany) . However, there are no reports of using a deep eutectic solvent (DES) as a coating for SBSE.…”

“…A stir bar with poly(dimethylsiloxane) coating is the most applied (polymeric) phase and is sold commercially under the trademark of Twister by GERSTEL GmbH & Co KG (Mülheim, Germany). 8 However, there are no reports of using a deep eutectic solvent (DES) as a coating for SBSE.…”

Application of gas flow headspace liquid phase micro extraction coupled with gas chromatography-mass spectrometry for determination of 4-methylimidazole in food samples employing experimental design optimization

“…An advantage associated to gas chromatography-mass spectrometry (GC–MS) method includes shorter sample preparation time, detection at low levels with high selectivity. While chromatography has the power of separating signals of matrix components from the analyte, the main drawbacks associated with this technique is unfeasibility of detecting low concentrations of analytes [ 16 ]. This problem can be overcome by applying a proper extraction technique prior to performing chromatography.…”

“…Techniques such as solid phase extraction [ 17 – 20 ], solid-phase micro-extraction (SPME) [ 21 ] dispersive micro-solid phase extraction [ 22 ], supercritical fluid extraction [ 23 ], cation exchange sorbents [ 24 ], enzyme-linked immunosorbent assay [ 25 ] and ion-pair extraction and derivatization [ 26 , 27 ] are excellent sample preparation techniques that are successfully employed to achieve this goal for the extraction and preconcentration of 4-MeI; however, they each require a specialized apparatus with some type of solid or polymeric sorbent to collect the analyte. For example, the main drawbacks of SPME are that its fibers are expensive and have a limited lifetime, as they tend to degrade with increased usage [ 16 ]. The prototype of single-drop microextraction (SDME) was developed by Jeannot and Cantwell [ 28 , 29 ] and has been recognized as one of the simplest miniaturized sample preparation tools for the isolation and preconcentration of many analytes from complicated sample matrices [ 30 ].…”