Development of a carbon nanotube‐coated stir bar for determination of organophosphorus pesticides in water

Abstract

In this study a new adsorptive coating was developed and used for simultaneous extraction and determination of different organophosphorus pesticides (OPPs) in water samples. The adsorption phase was developed by modification of multi‐walled carbon nanotubes. A magnetic stir bar was coated with the adsorption phase using sol–gel technique and used for extraction. After extraction, the analytes were desorbed thermally and determined by gas chromatography‐mass spectrometry (GC‐MS). The developed method was optimized and validated. The optimum condition were found as pH 6.5, salt concentration of 1% (w/v), adsorption condition of 35 °C and 30 min and stirring rate of 1500 rpm. Desorption step was programmed as 40 °C for 0.5 min, then to 300 °C (at 60 °C min−1, held for 5 min). The acquired calibration curves were linear (0.987 ≤ r2 ≤ 0.995) over the concentration range 0.02–8 μg L−1. For all of the analytes, the limit of detection was ≤0.01 μg L−1. Interday precision values were always ≤13.40% and the reproducibility of coating procedure, evaluated in term of relative standard deviation (RSD), was found acceptable (12% ≤ RSD ≤ 14%). The recoveries were in the range of 67–84% with RSD in the range of 10.2–13.5%. Good solvent and thermal resistance are the other advantages of the developed coating which makes it suitable for extraction of target compounds in water samples. The developed method was successfully applied to determine target OPPs in real samples. Based on the results Diazinon and Dichlorvos were found in more than 50% of the samples in the range of 0.06–0.27 µg L−1. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.

Analytical Extraction Methods and Sorbents’ Development for Simultaneous Determination of Organophosphorus Pesticides’ Residues in Food and Water Samples: A Review

“…To date, studies are limited on the application of SBSE, due to limited variety of stir-bar coatings since only PDMS is commercially available. Hence, a new sorbent coating has been prepared by using PDMS in combination with other materials that are commercially available such as polyvinyl alcohol, graphene, and multiwalled carbon nanotubes (MWCNTs) to enhance the extraction performance of SBSE [ 64 , 65 , 66 ].…”

“…Next, OH-functionalized multiwalled carbon nanotubes (OH-MWCNTs) were prepared by Ahmadkhaniha and Rastkari [ 65 ] as SBSE stir-bar coating for OPPs’ extraction from water samples coupled with GC-MS. Previously, they had prepared MWCNTs as SBSE coating material for OPPs’ and polycyclic aromatic hydrocarbons’ (PAHs) determination.…”

“…Therefore, OH-MWCNTs were used to enhance CNTs’ dispersion in a sol-gel system. The OH-MWCNTs were selected as they enhance CNTs’ solubility and generate stable structure, as this polymer binds the MWCNTs’ stationary phase to the growing silica network during polycondensation process [ 65 , 68 ]. The developed method employing the OH-MWCNTs’ sorbent and GC-MS showed low LOD (5–10 ng L −1 ) and satisfactory RSD (7.2–12.4%).…”

Optimization of a Multiresidue Analysis of 65 Pesticides in Surface Water Using Solid-Phase Extraction by LC-MS/MS

“…Liquid-liquid extraction (LLE) and solid-phase extraction (SPE) are the most common sample preparation techniques used as a purification and clean-up process prior to instrumental analysis [6,7]. Solid-phase extraction (SPE) is gaining much interest as it includes different simultaneous mechanisms such as adsorption, partition, and ionic exchange with less organic solvent [8]. Due to this popularity, sample preparation using SPE has increased intensely; debate on appropriate SPE sorbent and extraction conditions that results in high extraction efficiencies for multiclass of pesticides continues [9,10].…”

Multi-Residue Screening of Pesticides in Aquaculture Waters through Ultra-High-Performance Liquid Chromatography-Q/Orbitrap Mass Spectrometry

“…In the last few years, methods applied in pesticides based on GC or HPLC with high-resolution mass spectrometry (HRMS) have been increasingly explored [21][22][23]. Owing to the low concentration residues of contaminants in the environment and their complexity in the real samples, liquid-liquid extraction (LLE) and solid-phase extraction (SPE) are often used for extraction and purification of pesticides from water [1,24,25]. As the solid-phase extraction (SPE) allows the simultaneous enrichment and purification with less organic solvent, it is preferable for large volume samples pretreatment.…”