Synthesis and application of new silver and sulfur decorated S-doped reduced graphene oxide in ultra-trace analysis of pesticides by ion mobility spectrometry.

In this research study, a novel, facile, and affordable method is presented for the synthesis of a Ag/S/S-RGO nanocomposite. The resulting new nanocomposite was identified by FT-IR, XRD, FESEM, XPS, BET and EDX and employed as a rapid and effective adsorbent with acceptable absorption capacity for the analysis of various pesticides by dispersive solid-phase microextraction combined with ion mobility spectrometry. The main experimental parameters of the method were optimized such as the type of desorption solvent, pH of the sample solution, type of buffer, amount of the sorbent (Ag/S/S-RGO), sorption/desorption time, etc. Under the optimized conditions, linear dynamic ranges of 0.5-110.0, 1.0-110.0, and 0.8-90.0 ng mL-1 were achieved, with limits of detection of 0.25, 0.35, and 0.25 ng mL-1 for simazine, alachlor, and haloxyfop, respectively. The relative standard deviations (RSD%) were obtained as <5.0%. Eventually, the method was utilized for the simultaneous determination of simazine, alachlor, and haloxyfop in environmental and agricultural samples with recoveries between 95.0 and 104.6%.

Application of ZnS/S/S-RGO three-component nanocomposites in dispersive solid-phase microextraction coupled with ion mobility spectrometry for ultra-trace determination of multiclass pesticides.

A fast, effective, and sensitive dispersive solid-phase microextraction method coupled with ion mobility spectrometry for the simultaneous determination of bendiocarb, butachlor, and diazinon was developed using zinc sulfide/sulfur/sulfur-doped reduced graphene oxide (ZnS/S/S-RGO) nanocomposites. ZnS/S/S-RGO three-component nanocomposites were synthesized through a single-step solvothermal procedure, and their properties were characterized by FT-IR, XRD, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and energy-dispersive x-ray spectroscopy (EDX). The influence of different parameters was optimized on the efficiency of the extraction including the type and the volume of desorption solvent, pH, type and the volume of buffer, the amount of absorbent, sorption and  desorption times. Under the optimal conditions, linear ranges were achieved 0.8-110, 1.0-110, and 0.5-100 ng mL-1 with detection limits of 0.32±0.01, 0.40±0.02, and 0.27±0.02 ng mL-1 for bendiocarb, butachlor, and diazinon, respectively. The method was employed for the ultra-trace determination of the three pesticides in water, rice, and soil samples with acceptable recovery values within the range 96.6±4.8-104.4±6.4%.

Ultrasound-assisted dispersive liquid-liquid microextraction followed by ion mobility spectrometry for the simultaneous determination of bendiocarb and azinphos-ethyl in water, soil, food and beverage samples.

A sensitive and fast ultrasound-assisted dispersive liquid-liquid microextraction procedure combined with ion mobility spectrometry has been developed for the simultaneous extraction and determination of bendiocarb and azinphos-ethyl. Experimental parameters affecting the analytical performance of the method were optimized: type and volume of extraction solvent (chloroform, 150 µL), pH (9.0), type and volume of buffer (ammonium buffer pH = 9.0, 4.5 mL) and extraction time (3.0 min). Under optimum conditions, the linearity was found to be in the range of 2-40 and 6-100 ng/mL and the limits of detection (LOD) were 1.04 and 1.31 ng/mL for bendiocarb and azinphos-ethyl, respectively. The method was successfully validated for the analysis of bendiocarb and azinphos-ethyl in different samples such as waters, soil, food and beverage samples.

Application of cation-modified sulfur nanoparticles as an efficient sorbent for separation and preconcentration of carbamazepine in biological and pharmaceutical samples prior to its determination by high-performance liquid chromatography.

A simple and rapid solid phase extraction procedure using a mini-column packed with modified sulfur nanoparticles as a new, efficient and reusable sorbent has been developed for the preconcentration of carbamazepine prior to its determination by high performance liquid chromatography. This method is based on the retention of carbamazepine by modified sulfur nanoparticles which are quite efficient for fast adsorption and desorption of carbamazepine. An HPLC system including C18, 250×4.6mm column, methanol-acidic water (pH=2.6 by acetic acid) (60:40) as mobile phase and UV detector (λ=276nm) was used. The effects of multiple experimental conditions such as the effect of pH, type and volume of buffer, type and volume of eluent, sample and eluent flow rate, sorbent amount and interfering ions, on the analytical performance of the method were investigated. The calibration curve was linear in the range of 0.5-200ngmL-1 and LOD of the proposed method was found to be 0.16ngmL-1. The procedure was successfully applied for the determination of carbamazepine in pharmaceutical samples, human plasma and breast milk.