Development of a green rotating bar sorptive extraction coupled with GC/MS for determination of organophosphate pesticides in environmental waters

Effect of oxidation and dimensions of multi-walled carbon nanotubes on solid phase extraction and enrichment of some pesticides from environmental waters prior to their simultaneous determination by high performance liquid chromatography

A method based on gas chromatography–mass spectrometry (GC–MS), coupled with magnetic solid-phase extraction (SPE) with multi-walled carbon-nanotube (MWCNT)-coated iron oxide (Fe3O4) as the adsorbent, was developed for analyzing four organophosphate esters in ambient water samples. The magnetic, MWCNT composites were prepared by hydrothermal synthesis and characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, and superconducting quantum interference device magnetometry (SQUID). The extraction and desorption conditions, such as adsorbent dosage, adsorption time, eluent type, and eluent volume, were studied. The adsorbent was used to extract analytes within 50 min. The limit of detection (LOD) was between 0.038–1 μg/L, and the limit of quantitation (LOQ) was between 0.10–3.59 μg/L. The method was applied to analyze organophosphate esters in environmental water samples. A 72.5–89.1% recovery was obtained by analyzing spiked samples with low-, medium-, and high-concentration analytes. The relative standard deviations (RSDs) were less than 10%. This method displayed better sensitivity and accuracy; therefore, it could be successfully used to detect organophosphate esters in environmental water samples.

An ultrastable 2D covalent organic framework coating for headspace solid-phase microextraction of organochlorine pesticides in environmental water

A rapid, efficient, and new solvent terminated dispersive liquid-liquid microextraction technique coupled with HPLC was developed for selective extraction and analysis of s-triazine herbicides from environmental water samples. Important parameters influencing the extraction process including type and volume of extraction and disperser solvent, extraction time, sample pH, ionic strength, and extraction temperature were successfully optimized. Under the optimal conditions, there are excellent linear relationships between the analytical results and concentration in the range of 10-400 mg/L for atrazine, propazine, prometryn, and terbutryn. LOD and LOQ ranged from 0.60 to 2.33 μg/L and 2.0 to 7.7 μg/L, respectively. Performance of the analytical technique was evaluated by carrying out the repeatability and reproducibility analyses that were ranged from 2.86 to 5.66% and 4.64 to 5.89% for 100 μg/L of each target analyte, respectively. The proposed method has been successfully applied to the analysis of real water samples and acceptable relative recoveries over the range of 65.93-101.46%, with RSDs ≤ 8.80%, were obtained. The overall results have been compared with the literature values. Thus, the method developed could efficiently be used for selective extraction of the target analytes from complex matrices, particularly environmental waters.

A manganese dioxide-modified carboxylated graphene oxide (MnO2@CGO) nanocomposite was fabricated and utilized as a solid nanosorbent for extracting six organochlorine pesticides from environmental water samples. The target compounds, Hexachlorobenzene (HCB), β-Hexachlorocyclohexane (β-HCH), Heptachlor, Aldrin, Dieldrin, and o,p-Dichlorodiphenyltrichloroethane (o,p-DDT), were determined by micro-solid phase extraction (µ-SPE) coupled with gas chromatography-mass spectrometry (GC-MS) in selective ion monitoring mode. Key experimental factors influencing the extraction performance, such as sample pH, sorbent dosage, type and volume of eluting solvent, and time for desorption, were systematically optimized. Under the optimized conditions, the method showed good linearity (R2 = 0.998-1.000) within the concentration range of 0.1-5 ng L-1. The developed procedure was successfully applied to Nile River, agricultural wastewater, and groundwater samples, achieving recoveries between 87.1% and 101.2% with RSDs below 4.0%. The detection limits were 0.005-0.010 mg L-1 at a signal-to-noise ratio of 3.0. Overall, the MnO2@CGO-based µ-SPE method offers a sensitive, reliable, and straightforward approach for monitoring trace levels of organochlorine pesticides in environmental waters.

SPE using a cross-linked starch-based polymer (CSMDI) as an adsorbent for the determination of four nitrophenols at trace levels from aqueous solution was investigated. The CSMDI was synthesized from native starch using 4,4'-methylenebisphenyldiisocyanate as a cross-linking agent in dry DMF. Parameters affecting the extraction efficiency including the pH of the water sample, type of eluent and its volume, flow rate, sample volume, and methanol content were investigated and optimized. The optimized results exhibited excellent linear relationships (R(2) > 0.995) for all the nitrophenols over the range of 2.0-200 ng/mL, with the RSD values in the range of 2.9-5.7% (n = 5). The LODs ranged from 0.08-0.34 ng/mL (S/N = 3) for the four nitrophenols tested under optimum conditions. The developed method has been successfully applied for the analysis of several real environmental water samples including tap, river, and reservoir water. These results indicated that the CSMDI had a tremendous potential for the enrichment and determination of nitrophenols at trace levels in environmental water samples.

Environmental occurrence of CECs poses a great threat to both aquatic life and human health. The aim of this study was to optimize and validate SPE/LC-(ESI)MS-MS method for simultaneous quantitative monitoring of two sub-classes of CECs (pharmaceuticals and hormones) and to estimate the concentrations of select CECs in environmental water samples. For all the tested analytes, recoveries in laboratory reagent water were greater than 81%. Average percent (relative standard deviation) RSD of the analytes in recovery, repeatability, and reproducibility experiments were ≤ 10%. Determination coefficients (r2) of primidone, diclofenac, testosterone, and progesterone were estimated to be 0.9979, 0.9972, 0.9968, and 0.9962, respectively. Limits of detection (LOD) for primidone, diclofenac, testosterone, and progesterone were 4.63ng/L, 5.36ng/L, 0.55ng/L, and 0.88ng/L, respectively. Limits of quantification (LOQ) for primidone, diclofenac, testosterone, and progesterone were 14.72ng/L, 17.06ng/L, 1.766ng/L, and 2.813ng/L, respectively. Average recoveries in environmental water and wastewater samples were greater than 74% and RSD were ≤ 7%. Trace levels (68.33-125.70ng/L) of primidone were detected in four environmental water samples, whereas diclofenac was not detected in any of the tested sample. Trace levels of progesterone were observed in two environmental samples (16.64-203.73ng/L), whereas testosterone was detected in STP inlet sample (178.16ng/L).

For graphene oxide (GO) composite hydrogels, a two-dimensional GO material is introduced into them, whose special structure is used to improve their properties. GO contains abundant oxygen-containing functional groups, which can improve the mechanical properties of hydrogels and support the application needs. Especially, the unique-conjugated structure of GO can endow or enhance the stimulation response of hydrogels. Therefore, GO composite hydrogels have a great potential in the field of wearable devices. We referred to the works published in recent years, and reviewed from these aspects: (a) structure of GO; (b) factors affecting the mechanical properties of the composite hydrogel, including hydrogen bond, ionic bond, coordination bond and physical crosslinking; (c) stimuli and signals; (d) challenges. Finally, we summarized the research progress of GO composite hydrogels in the field of wearable devices, and put forward some prospects.

Sodium dodecyl sulfate coated amino-functionalized magnetic iron oxide nanoparticles were used as an efficient adsorbent for rapid removal and preconcentration of three important organophosphorus pesticides, chlorpyrifos, diazinon and phosalone, by ultrasound-assisted dispersive magnetic solid-phase microextraction. Fabrication of amino-functionalized magnetic nanoparticles was certified by characteristic analyses, including Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy. Affecting parameters on the removal efficiency were investigated and optimized through half-fractional factorial design and Doehlert design, respectively. The analysis of analytes was performed by high-performance liquid chromatography with ultraviolet detection. Under the optimum conditions, extraction recoveries for 20ng/mL of organophosphorus pesticides were in the range of 84-97% with preconcentration factors in the range of 134-155. Replicating the experiment in above condition for five times gave the relative standard deviations <6%. The calibration curves showed high linearity in the range of 0.2-700ng/mL and the limits of detection were in the range of 0.08-0.13ng/mL. The proposed method was successfully applied for both removal and trace determination of these three organophosphorus pesticides in environmental water and fruit juice samples.

Effects of in situ cross-linked graphene oxide-containing gelatin methacrylate anhydride hydrogel on wound vascularization of full-thickness skin defect in mice

Dual modification of oil palm leaves-derived silica for simultaneous magnetic solid phase extraction of organophosphorus and organochlorine pesticides in environmental water.

Versatile magnetic carbon nanotubes for sampling and pre concentration of pesticides in environmental water

Covalent organic framework-based magnetic solid phase extraction coupled with micellar electrokinetic chromatography for the analysis of trace organophosphorus pesticides in environmental water and atmospheric particulates

Porous lead(II)-based metal organic nanotubes as an adsorbent for dispersive solid-phase extraction of polybrominated diphenyl ethers from environmental water samples

: A rapid and sensitive assay was developed for the detection of low numbers of viable Vibrio cholerae and Shigella spp. cells in environmental and drinking water samples. Water samples were filtered, and the filters were enriched in a non-selective medium. The enrichment cultures were prepared for polymerase chain reactions (PCR) by a rapid and simple DNA extraction procedure consisting of boiling. Seminested PCR, based on specific amplification of the cholera toxin operon of V. cholerae and the invasion plasmid antigen gene (ipaH) of virulent Shigella spp., was performed and the PCR products were visualised by agarose gel electrophoresis. The assay allowed the detection of as few as 1 cfu/100 ml of V. cholerae and 8 cfu/100 ml of Shigella cells. A comparison of the PCR method and culturing methods by using environmental water samples showed that the PCR method has a higher level of sensitivity than culturing methods. As an application of the PCR detection protocol, environmental water samples were screened for the presence of V. cholerae and Shigella spp. Positive amplifications resulted from V. cholerae and Shigella species in environmental samples. The results obtained indicate that the described seminested PCR has the advantage of a rapid turn-around time and fulfils the requirements of sensitivity for use in an environmental laboratory. Keywords: Vibrio cholerae, Shigella, Water-borne pathogens, Polymerase chain reaction, Environmental waters, Drinking water, Detection (WaterSA: 2003 29(2): 177-182)