Extraction and determination of pesticide residues in water using carbon nanotubes coupled with gas chromatography-mass spectroscopy

Multi-walled carbon nanotubes (MWCNT) were used as an adsorbent in a solid-phase extraction (SPE) process to detect pesticide residues in water. The MWCNT were prepared with polyvinyl pyrrolidone and polysilazane liquid by pyrolysis. The morphology and integrity of MWCNT were characterized by Fourier-transform infrared spectroscopy, scanning electron microscope, X-ray diffractometer, and transmission electron microscope. Water samples including pesticides were passed through cartridges containing the MWCNT, where pesticides in the water were concentrated by adsorption. The analytical method for the detection of pesticides in dilute solution was proposed by using MWCNT as an adsorbent with gas chromatography/mass spectrometry for quantification of fenpropathrin, alphacypermethrin, and deltamethrin. The adsorption amounts of pesticides on the MWCNT were analyzed to identify the effects of temperature, flow rate, acidity, ionic strength, and analytes volume. The MWCNT-packed cartridges withstand a high load of water samples in the lowest concentration of 0.03 ng/L passing through for the extraction of pesticide residues at trace levels when compared with the commercial C18 cartridges, due to their large surface area and adsorption capacity.