Creative Chemistry and Innovation Research Unit, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahasarakham University, Maha Sarakham 44150, Thailand.
Materials Chemistry Research Center, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand.
Molecules. 2018 May 12;23(5):1165. doi: 10.3390/molecules23051165.
An effective pre-concentration method, namely amended-cloud point extraction (CPE), has been developed for the extraction and pre-concentration of neonicotinoid insecticide residues. The studied analytes including clothianidin, imidacloprid, acetamiprid, thiamethoxam and thiacloprid were chosen as a model compound. The amended-CPE procedure included two cloud point processes. Triton™ X-114 was used to extract neonicotinoid residues into the surfactant-rich phase and then the analytes were transferred into an alkaline solution with the help of ultrasound energy. The extracts were then analyzed by high-performance liquid chromatography (HPLC) coupled with a monolithic column. Several factors influencing the extraction efficiency were studied such as kind and concentration of surfactant, type and content of salts, kind and concentration of back extraction agent, and incubation temperature and time. Enrichment factors (EFs) were found in the range of 20⁻333 folds. The limits of detection of the studied neonicotinoids were in the range of 0.0003⁻0.002 µg mL which are below the maximum residue limits (MRLs) established by the European Union (EU). Good repeatability was obtained with relative standard deviations lower than 1.92% and 4.54% for retention time () and peak area, respectively. The developed extraction method was successfully applied for the analysis of water samples. No detectable residues of neonicotinoids in the studied samples were found.
一种有效的预浓缩方法，即改良浊点萃取（CPE），已被开发用于提取和浓缩新烟碱类杀虫剂残留。选择了噻虫嗪、吡虫啉、噻虫胺、噻虫啉和噻虫砜作为模型化合物。改良的 CPE 程序包括两个浊点过程。使用 Triton™ X-114 将新烟碱类残留物萃取到表面活性剂富相，然后在超声能量的帮助下将分析物转移到碱性溶液中。然后通过高效液相色谱（HPLC）与整体柱分析提取物。研究了影响萃取效率的几个因素，如表面活性剂的种类和浓度、盐的种类和含量、反萃取剂的种类和浓度、孵育温度和时间。富集因子（EF）在 20-333 倍范围内。研究的新烟碱类的检测限在 0.0003-0.002 µg mL 范围内，低于欧盟（EU）规定的最大残留限量（MRL）。保留时间（）和峰面积的相对标准偏差分别低于 1.92%和 4.54%，重复性良好。所开发的萃取方法成功应用于水样的分析。在所研究的样品中未发现新烟碱类的可检测残留。
