Homogeneous liquid–liquid extraction combined with gas chromatography–electron capture detector for the determination of three pesticide residues in soils

Synthesis of green nanosorbent from bovine serum albumin and curcumin for magnetic solid phase extraction of pesticides from food samples

For the first time, a magnetic carbon nanocomposite was synthesized using one-step hydrothermal procedure, employing bovine serum albumin, curcumin, and ferric ammonium citrate. Additionally, the application of this novel composite as an adsorbent for magnetic dispersive solid phase extraction of fungicides and pesticides from water and food samples is a unique aspect of this study. Under optimum conditions (salt concentration: 5.0% w/v, pH: 7.0, desorption solvent: ethanol, sorbent amount: 20 mg, extraction time: 20 min, desorption time: 3 min, stirring rate: 500 rpm, sample volume: 30 mL, extraction temperature: room temperature, and desorption solvent volume: 150 μL) linearity (2.5 to 1400 ng mL-1), coefficients of determination (R2 ≥ 0.997), limits of detection (0.75 to 1.5 ng mL-1), and limits of quantification (2.5 to 5.0 ng mL-1) were achieved. The method validation results showed extraction recovery ranging from 71.2% to 93.4%, and preconcentration factors ranging from 142.5 to 186.1.

Development of Copper Nanoclusters-Based Turn-Off Nanosensor for Fluorescence Detection of Two Pyrethroid Pesticides (Cypermethrin and Lambda-Cyhalothrin)

Fluorescent copper nanoclusters (Cu NCs) were synthesized by using Withania somnifera (W. somnifera) plant extract as a biotemplate. Aqueous dispersion of W. somnifera-Cu NCs displays intense emission peak at 458 nm upon excitation at 350 nm. This fluorescence emission was utilized for the detection of two pyrethroid pesticides (cypermethrin and lambda-cyhalothrin) via "turn-off" mechanism. Upon the addition of two pyrethiod pesticides independently, the fluorescence emission of W. somnifera-Cu NCs was gradually decreased with increasing concentrations of both pesticides. It was noticed that the decrease in emission intensity at 458 nm was linearly dependent on the logarithm of both pesticides concentrations in the ranges of 0.01-100 μM and of 0.05-100 μM for cypermethrin and lambda-cyhalothrin, respectively. Consequently, the limits of detection were found to be 27.06 and 23.28 nM for cypermethrin and lambda-cyhalothrin, respectively. The as-fabricated W. somnifera-Cu NCs acted as a facile sensor for the analyses of cypermethrin and lambda-cyhalothrin in vegetables (tomato and bottle gourd), which demonstrates that it could be used as portable sensing platform for assaying of two pyrethroid pesticides in food samples.

Phytoremediation and Bioremediation of Pesticide-Contaminated Soil

Management and destruction of obsolete pesticides and the remediation of pesticide-contaminated soil are significant global issues with importance in agriculture, environmental health and quality of life. Pesticide use and management have a history of problems because of insufficient knowledge of proper planning, storage, and use. This manuscript reviews recent literature with an emphasis on the management of obsolete pesticides and remediation of pesticide-contaminated soil. The rhizosphere of plants is a zone of active remediation. Plants also take up contaminated water and remove pesticides from soil. The beneficial effects of growing plants in pesticide-contaminated soil include pesticide transformation by both plant and microbial enzymes. This review addresses recent advances in the remediation of pesticide-contaminated soil with an emphasis on processes that are simple and can be applied widely in any country.

Tuning of gold nanoclusters sensing applications with bovine serum albumin and bromelain for detection of Hg2+ ion and lambda-cyhalothrin via fluorescence turn-off and on mechanisms

Herein, fluorescent gold nanoclusters (Au NCs) were obtained by one-pot synthetic method using bovine serum albumin (BSA) and bromelain as templates. As-synthesized fluorescent Au NCs were stable and showed bright red fluorescence under UV lamp at 365 nm. The fluorescent Au NCs exhibit the emission intensity at 648 nm when excited at 498 nm. Various techniques were used such as spectroscopy (UV-visible, fluorescence, and Fourier-transform infrared), high-resolution transmission electron microscopy, and dynamic light scattering for the characterization of fluorescent Au NCs. The values of I₀/I at 648 nm are proportional to the concentrations of Hg²⁺ ion in the range from 0.00075 to 5.0 μM and of lambda-cyhalothrin in the range from 0.01 to 10 μM with detection limits of 0.0003 and 0.0075 μM for Hg²⁺ ion and lambda-cyhalothrin, respectively. The practical application of the probe was successfully demonstrated by analyzing Hg²⁺ ion and lambda-cyhalothrin in water samples. In addition, Au NCs used as probes for imaging of Simplicillium fungal cells. These results indicated that the as-synthesized Au NCs have proven to be promising fluorescent material for the sensing of Hg²⁺ ion and lambda-cyhalothrin in environmental and for imaging of microorganism cells in biomedical applications.

Silicon hybrid plasmonic microring resonator for sensing applications

A novel silicon hybrid plasmonic microring resonator consisting of a silver nanoring on top of a silicon-on-insulator ring is proposed and investigated theoretically for possible applications in sensing at the deep subwavelength scale. By using the finite-element method, insight into how the mode properties (Q factor, effective mode volume, energy ratio, sensitivity) depend on the geometric structure of the hybrid microring resonator is presented. Simulation results reveal that this kind of hybrid microcavity maintains a high Q factor ∼600, an ultrasmall mode volume of 0.15  μm³, and high sensitivity of 497  nm/refractive index unit for refractive index sensing. The hybrid plasmonic microcavity with optimized geometric structures presented provides the potential for ultracompact sensing applications.

Applications of liquid-phase microextraction in the sample preparation of environmental solid samples

Solvent extraction remains one of the fundamental sample preparation techniques in the analysis of environmental solid samples, but organic solvents are toxic and environmentally harmful, therefore one of the possible greening directions is its miniaturization. The present review covers the relevant research from the field of application of microextraction to the sample preparation of environmental solid samples (soil, sediments, sewage sludge, dust etc.) published in the last decade. Several innovative liquid-phase microextraction (LPME) techniques that have emerged recently have also been applied as an aid in sample preparation of these samples: single-drop microextraction (SDME), hollow fiber-liquid phase microextraction (HF-LPME), dispersive liquid-liquid microextraction (DLLME). Besides the common organic solvents, surfactants and ionic liquids are also used. However, these techniques have to be combined with another technique to release the analytes from the solid sample into an aqueous solution. In the present review, the published methods were categorized into three groups: LPME in combination with a conventional solvent extraction; LPME in combination with an environmentally friendly extraction; LPME without previous extraction. The applicability of these approaches to the sample preparation for the determination of pollutants in solid environmental samples is discussed, with emphasis on their strengths, weak points and environmental impact.

Automated QuEChERS tips for analysis of pesticide residues in fruits and vegetables by GC-MS

This paper reports the development of an automated method of QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) using pipet tips fitted with filtration screens and containing primary-secondary amine, magnesium sulfate, and graphitized carbon black. These tips are referred to as "QuEChERS Tips". Using loosely contained sorbent, dispersive solid phase extraction (dSPE) cleanup was performed with the QuEChERS Tips and automation. The main advantage of the QuEChERS Tips is that they are readily automated because this dSPE method does not require centrifugation. High recoveries (70-117%) and good reproducibilities (<12%) are shown for over 200 pesticides using automated QuEChERS Tips and GC-MS in various sample matrices.

Determination of organophosphorus pesticides in soil by dispersive liquid-liquid microextraction and gas chromatography

In this article, a rapid and sensitive sample pretreatment technique for the determination of organophosphorus pesticides (OPPs) in soil samples is developed by using dispersive liquid-liquid microextraction (DLLME) combined with gas chromatography-flame photometric detection. Experimental conditions, including the kind of extraction and disperser solvent and their volumes, the extraction time, and the salt addition, are investigated, and the following experiment factors are used: 20 µL chlorobenzene as the extraction solvent; 1.0 mL acetonitrile as the disperser solvent; no addition of salt; and an extraction time of 1 min. Under the optimum conditions, the linearities for the three target OPPs (ethoprophos, chlorpyriphos, and profenofos) are obtained by five points in the concentration range of 2.5-1500 µg/kg, and three replicates are used for each point. Correlation coefficients vary from 0.9987 to 0.9997. The repeatability is tested by spiking soil samples at a concentration level of 5.0 µg/kg. The relative standard deviation (n = 3) varied between 2.0% and 6.6%. The limits of detection, based on a signal-to-noise ratio (S/N) of 3, range from 200 to 500 pg/g. This method is applied to the analysis of the spiked samples S1, S2, and S3, which are collected from the China Agriculture University's orchard, lawn, and garden, respectively. The recoveries for each target analyte are in the range between 87.9% and 108.0%, 87.4% and 108.0%, and 86.7% and 107.2%, respectively.

Rapid and simple low density miniaturized homogeneous liquid-liquid extraction and gas chromatography/mass spectrometric determination of pesticide residues in sediment

A simple, rapid and environmentally friendly analytical methodology is developed for extraction of pesticides (diazinon, chlorpyrifos and trifluralin) from sediment samples based on a technique called low density miniaturized homogenous liquid-liquid extraction (LDMHLLE) prior gas chromatography mass spectrometry determination. The method based on homogeneous liquid-liquid extraction with methanol containing n-hexane as a solvent of lower density than water (n-hexane). After addition of water, n-hexane solvent immediately forms a distinct water immiscible phase at the top of the vial, which can be easily separated and injected to the GC/MS instrument for quantification. Acquisition was performed in the selected ion monitoring mode. The limits of detection were estimated for the individual pesticides as 3S(b) (three times of the standard deviation of baseline) of the measured chromatogram for pesticides. The proposed method is very fast, simple, and sensitive without any need for stirring and centrifugation and applied to real sediment samples, successfully.

Solid-phase extraction combined with dispersive liquid-liquid microextraction for the determination for polybrominated diphenyl ethers in different environmental matrices

An analytical method, solid-phase extraction combined with dispersive liquid-liquid microextration (SPE-DLLME), was established to determine polybrominated diphenyl ethers (PBDEs) in water and plant samples. After concentration and purification of the samples in LC-C18 column, 1.0-mL elution sample containing 22.0 microL 1,1,2,2-tetrachloroethane was injected rapidly into the 5.0-mL pure water. After extraction and centrifuging, the sedimented phase was injected rapidly into gas chromatography with electron-capture detection (GC-ECD). For water samples, enrichment factors (EFs) are in the range of 6838-9405 under the optimum conditions. The calibration curves are linear in the range of 0.1-100 ng L(-1) (BDEs 28, 47) and 0.5-500 ng L(-1) (BDEs 100, 99, 85, 154, 153). The relative standard deviations (RSDs) and the limits of detection (LODs) are in the range of 4.2-7.9% (n=5) and 0.03-0.15 ng L(-1), respectively. For plant samples, RSDs and LODs are in the range of 5.9-11.3% and 0.04-0.16 microg kg(-1), respectively. The relative recoveries of well, river, sea, leachate, and clover samples, spiked with different levels of PBDEs, are 66.8-94.1%, 72.2-100.5%, 74.5-110.4%, 62.1-105.1%, 66.1-91.7%, 62.4-88.9%, and 64.5-83.2%, respectively. The results show that SPE-DLLME is a suitable method for the determination of PBDEs in water and plant samples.