Nanoparticle-assisted applications for low detection limits in pesticide samples

With the growth of the global population, the demand for vegetables and fruits has significantly increased. Various chemicals are used to increase yields, and pesticides are used excessively against pests. The use of pesticides is an important agricultural control method used to protect products from the damage caused by diseases, pests, and weeds, and to produce quality crops. As the global population increases, the use of pesticides has become necessary to meet the rising demand for food. However, although pesticide use boosts production, it poses significant risks to the environment and human health. Therefore, it is important to monitor the maximum residue limits (MRLs) that may result from pesticide use. Furthermore, pesticides not only remain in food but also contaminate rivers, lakes, and oceans through rainwater and irrigation during planting. In this study, research was conducted on pesticides containing zoxamide, which is widely used in vegetable cultivation. A sensitive and accurate analytical method based on dispersed solid-phase extraction (DSPE) was developed for the determination of trace levels of zoxamide using gas chromatography-mass spectrometry (GC-MS). In this study, optimal conditions for the analysis of zoxamide-containing samples were examined. Amidosulphonic acid-coated Fe₃O₄ magnetic nanoparticles were used as the adsorbent for the extraction process for GC-MS determination. To determine optimal conditions, parameters such as the type and amount of nanoparticle, selection and volume of the pH buffer, stirring type, and stirring time were tested.A calibration curve was established with the zoxamide standard in the range of 0.05–2.0 mg/L. In studies conducted on the water sample, the zoxamide concentration was spiked to 0.2 mg/L, and based on consecutive GC-MS measurements, the limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.0362 and 0.121 mg/L, respectively. Similarly, consecutive GC-MS measurements were performed on the sample solutions obtained through the DSPE process by adding nanoparticles and pH buffer to the prepared water sample, and LOD-LOQ values of 0.0077 and 0.0257 mg/L were obtained. When LOQ values are analysed, there was a 5-fold increase. Zoxamide was not found in the mains water selected as real samples. Therefore, spiking was performed in the experiments. For this, it was determined that the nanoparticle completely adsorbed the zoxamide molecules in the sample when all the optimum conditions were applied. Thus, the study is a new method for both pretreatment and removal of pesticides.