Dispersive Solid-Phase Extraction Clean-up Combined with Dispersive Liquid–Liquid Microextraction for the Determination of Neonicotinoid Insecticides in Vegetable Samples by High-Performance Liquid Chromatography

Abstract

Dispersive solid-phase extraction (DSPE) cleanup combined with dispersive liquid-liquid microextraction (DLLME) has been developed as a new approach for the extraction of neonicotinoid insecticides in vegetable samples prior to high-performance liquid chromatography with diode array detection. In the DSPE-DLLME method, neonicotinoid insecticides were first extracted with acetonitrile from vegetable samples, followed by clean-up by a DSPE with primary secondary amine and multi-walled carbonnanotubes as sorbents. A 2.5-mL aliquot of the resulting extract was then added into a centrifuge tube containing 10 mL of water, 0.8 g NaCl, and 200-μL chloroform (as the extraction solvent) for DLLME procedure. Under the optimum conditions, the enrichment factors for the compounds were in the range between 110 and 243. The linearity of the method was in the range from 5.0 to 300 ng g −1 with the correlation coefficients (r) ranging from 0.9989 to 0.9998. The detection limits of the method were 0.5-1.0 ng g −1 . The repeatability of the method expressed as the relative standard deviations by five parallel experiments at the concentration levels of 10 and 50 ng g −1 each of the neonicotinoid insecticides in tomato or cucumber samples varied from 3.6% to 5.8%. The developed method has been successfully applied for the analysis of target neonicotinoid insecticides (acetamiprid, imidacloprid, thiacloprid, and thiamethoxam) in tomato and cucumber samples. The recoveries of the method for the target neonicotinoid insecticides from the vegetable samples at spiking levels of 10.0 and 50.0 ng g −1 were in the range between 84.6% and 97.5% (n=5).

UHPLC-DAD method for the determination of neonicotinoid insecticides in single bees and its relevance in honeybee colony loss investigations

“…In these methods, but also in methods for the analysis of simpler matrices of interest (i.e., honey [36,37], fruits [38][39][40][41][42], or vegetables [41][42][43][44][45][46][47]), great effort has been devoted to both extraction and cleanup procedures that precede instrumental analysis [48]. To obtain satisfactory recovery factors for both neonicotinoids and their main metabolites, several versions of the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method originally proposed by Anastassiades et al [49] were developed [33,35,37,40,46].…”

Response Surface Modeling of Ultrasound-Assisted Dispersive Liquid–Liquid Microextraction for Determination of Benzene, Toluene and Xylenes in Water Samples: Box–Behnken Design

“…The reason could be explained that at a low methanol volume, a cloudy state could not be well formed; therefore, the peak area is low. At a higher methanol volume, the solubility of the BTX in water was increased, thereby; the peak area was decreased due to the decrease of distribution coefficient (Wu et al 2011). Therefore, based on the experimental results, 0.5 mL of methanol was chosen for subsequent studies.…”

“…This technique was reported for the first time in a method for the determination of organophosphorus pesticides in water (Rezaee et al 2006). However, this method has also been widely used for the extraction and pre-concentration of organic and inorganic compounds (Baliza et al 2009;Wu et al 2011;Yan et al 2011). DLLME is based on the formation of the fine droplets of an extractant in a sample solution when a water-immiscible extraction solvent (extractant) dissolved in a water-miscible organic dispersive solvent rapidly injected into a sample solution.…”

“…The advantages of the DLLME procedure are fast, simplicity of operation, low cost, green extraction procedure (the consumption of organic solvent is reduced to the microliter) and high enrichment factor (Wu et al 2011).…”

Recent Developments and Applications of Microextraction Techniques for the Analysis of Pesticide Residues in Fruits and Vegetables

“…Neonicotinoid insecticides was also analyzed in apple using chlorobenzene (9 µL) and acetone (1 ml) [112], and in tomato and cucumber using tricholoromethane (200 µL) and acetonitrile (2.5 ml) [113]. Multiclass pesticides were determined in banana [114], table grape and plum [115], using ionic liquid ([C6MIm][PF6]) based extraction solvent and methanol (714 µL) and in apple juice using tetrachloromethane (100 µL) and acetone (500 µL).…”