Detection Of Chlorophenols Research Articles

Extraction and detection of chlorophenols in water samples using deep eutectic solvent-based dispersive liquid–liquid microextraction coupled with HPLC-UV

A dispersive liquid–liquid microextraction (DLLME) technique utilizing a low-density hydrophobic deep eutectic solvent (LD-HDES) based on the combination of DL-Menthol and L-lactic acid was developed. The developed sample preparation technique (LD-HDES-DLLME) coupled with liquid chromatography equipped with an ultraviolet detector (HPLC-UV) method was applied to determine the chlorophenols (CPs) in waters (drinking water, river water, and wastewaters). The DL-Menthol as a hydrogen bond acceptor (HBA) and L-lactic acid used as a hydrogen bond donor (HBD) for the deep eutectic solvent synthesis. The formed deep eutectic solvent was confirmed by FTIR, and the factors affecting the LD-HDES-DLLME process were carefully optimized. The developed LD-HDES-DLLME-HPLC-UV method exhibited good linearities for all studied CPs, correlation coefficient (R2) values ≥0.9993, LODs were in between 0.02 and 0.05 ng mL−1 for all the CPs, LOQs obtained were in between 0.06 and 0.15 ng mL−1, the method precision (RSDs) values are ≤8.8 %. The relative recoveries of the developed technique were studied at three levels; the obtained recoveries are between 90 ∼ 119 %, with RSDs ≤ 9.5 % for studied water samples. The proposed LD-HDES-DLLME-HPLC-UV method possesses substantial merits such as selectivity, use of less harmful solvent for the extraction, avoiding the use of toxic organic solvents, and short extraction time.

Electropolymerized Aniline-Based Stainless Steel Fiber Coatings Modified by Multi-Walled Carbon Nanotubes for Electroanalysis of 4-Chlorophenol.

In this paper, a stainless steel fiber coated electropolymerized aniline, without and with carbon nanotubes (SS/PANI and SS/PANI/CNT), along with CNTs modified carbon paste electrodes (CPEs), were prepared. The electrodes were characterized by differential pulse voltammetry (DPV) and applied for the detection of 4-chlorophenol (4-CP). For all the electrodes, the oxidative peak current showed a linear dependence on the 4-CP concentration in the range of 0.05–0.5 mmol/L with R2 ≥ 0.991. SS/PANI/CNT electrodes showed greater sensitivity for the detection of the 4-CP than the SS/PANI and CPEs. For all of the aniline-based stainless steel electrodes, both the LOD and LOQ decreased with the increase in the number of electropolymerization cycles. The lowest LOD (0.38 µmol/L) and LOQ (1.26 µmol/L) were observed for the SS/PANI/CNT electrode modified in aniline solution during 30 cycles. The methods were successfully applied to the analysis of 4-CP in real samples (tap water and river water). The results demonstrated the good agreement of the added and found concentrations of the 4-CP. The recovery and precision were from 95.12% to 102.24% and from 1.53% to 6.79%, respectively. The proposed electrodes exhibited acceptable reproducibility, admirable stability, and adequate repeatability and showed potential for the analysis of 4-CP in water.

High-sensitive molecularly imprinted sensor with multilayer nanocomposite for 2,6-dichlorophenol detection based on surface-enhanced Raman scattering.

This study describes the preparation of a novel multilayer sensor based on molecularly imprinted polymers (MIPs) for the detection of trace-level chlorophenols by surface-enhanced Raman scattering (SERS). Composites of SiO2/reduced graphene oxide/gold (SiO2/rGO/Au, SGA) are chosen as the SERS substrates. The fabricated composites are able to enhance the SERS sensitivity, and the addition of MIPs improves the selectivity of traditional SERS substrates. Furthermore, the sensor's detection sensitivity and selectivity are improved by including two functional monomers, namely methacrylic acid (MAA) and acrylamide (AM) containing different functional groups. Finally, in to more effectively balance the selectivity of MIPs shell and the sensitivity of SERS detection, the prepared substrates are surface-modified with polydopamine (pDA) and prepared by atom transfer radical polymerization (ATRP). It is confirmed that the prepared SGA-MIPs exhibits relatively good sensitivity and selectivity in the detection of chlorophenols. Importantly, all the investigations are conducted in environmentally friendly aqueous solution, which enables scaling-up without causing pollution.

Electrocatalytic behavior of single walled carbon nanotubes with alkylthio-substituted cobalt binuclear phthalocyanines towards oxidation of 4-chlorophenols

This work describes the adsorption of synthesized cobalt mono (CoPc) and binuclear phthalocyanines (CoBiPc) with single walled carbon nanotubes (SWCNT) to form SWCNT-CoPc or SWCNT-CoBiPc as non-covalent conjugates onto glassy carbon electrodes (GCE). The cobalt complexes and their SWCNT-conjugate-modified electrodes were studied for their electrocatalytic oxidation towards 4-chlorophenol. All modified electrodes showed improved catalytic current and stability towards the detection of 4-chlorophenol. The best activity was observed for the SWCNT-CoBiPc2 system in terms of current response and the SWCNT-CoBiPc1 system in terms of resistance to electrode fouling.

Photoelectrochemical sensing of 4-chlorophenol based on Au/BiOCl nanocomposites

The Au/BiOCl composites have been prepared by a facile one-pot ethylene glycol (EG) assisted solvothermal reaction in the presence of ionic liquid 1-hexadecyl-3-methylimidazolium chloride ([C16mim]Cl). During the synthesis procedure, the [C16mim]Cl has been used as Cl source, solvent of this system, and dispersing agent to effectively disperse Au on the surface of BiOCl. The as-prepared samples have been systematically characterized by multiple instruments to investigate the structure, morphology, and photoelectrochemical properties. According to the photoelectrochemical data, the Au/BiOCl composites exhibit better photoelectrochemical performance toward the detection of 4-chlorophenol than that of the pure BiOCl. The photocurrent response of Au/BiOCl modified electrode is high and stable under light irradiation. The proposed Au/BiOCl modified electrode shows a wide linear response ranging from 0.16 to 20mgL−1 with detection limit of 0.05mgL−1. It indicates a dramatically promising application of bismuth oxyhalides in photoelectrochemical detection. It will be expected that the present study may be lightly extended to the monitor of other organic pollutants by photoelectrochemical detection of the Au/BiOCl composites.

Characterization of Mo-MCM-41 and its Electrochemical Sensing Property

By direct hydrothermal method, Mo-MCM-41 mesoporous catalysts with different Si/Mo ratio were prepared. Mo-MCM-41 was characterized by XRD, FT-IR, and DRS UV-Vis spectroscopy. The morphological property of the samples was characterized by SEM. The SEM images show the agglomeration of the particles. The synthesized Mo-MCM-41 was used to modify glassy carbon electrode (Mo-MCM-41/GCE). The detection of 4-chlorophenol (4-CP) using Mo-MCM-41/GCE in a pH 7.4 phosphate buffer solution (PBS) was carried out by cyclic voltammetry (CV). At the Mo-MCM-41/GCE, 4-CP is oxidized at less positive potential with larger current response than the bare GCE.

Preparation of magnetic poly(diethyl vinylphosphonate-co-ethylene glycol dimethacrylate) for the determination of chlorophenols in water samples

In this work, a novel type of magnetic polymer particle, magnetic poly(diethyl vinylphosphonate-co-ethylene glycol dimethacrylate) [Fe3O4@p(DEVP-co-EDMA)], was successfully synthesized and applied for the extraction and determination of chlorophenols in water samples by coupling with high-performance liquid chromatography (HPLC). Fe3O4@p(DEVP-co-EDMA) was synthesized by a simple seeded radical polymerization method and exhibited well-defined core–shell structure and good magnetic response ability. In addition, the magnetic polymer had the advantages of abundant adsorption sites and high enrichment efficiency. Due to the presence of PO group in the skeleton of polymer, the magnetic polymer material displayed excellent extraction performance for chlorophenols, such as 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP) and 2,4,6-trichlorophenol (2,4,6-TCP). Hydrophobic skeleton of the magnetic polymer also provided strong interaction with the target analytes, especially pentachlorophenol (PCP) which is a kind of non-polar chlorophenol. Desorption solution, pH of water sample, extraction time and desorption time, the amount of adsorbent, and the volume of desorption solution were optimized. Under the optimized conditions, the linear ranges of four chlorophenols were 2–500ng/mL with the limits of detection (S/N=3) ranging from 0.20 to 0.34ng/mL. The repeatability was investigated by evaluating the intra- and inter-day precisions with relative standard deviations (RSDs) lower than 15.0%. The recoveries for real water samples were in the range of 92.7–108.0%. Collectively, the results indicated that the novel Fe3O4@p(DEVP-co-EDMA) was successfully applied in the extraction and detection of chlorophenols from water samples, and the magnetic polymer particle showed potential applications in the analysis of polar compounds.

Assessment of priority phenolic compounds in sediments from an extremely polluted coastal wetland (Lake Maryut, Egypt)

Although high concentrations of trace organic pollutants were recorded along the Egyptian Mediterranean Coast and its corresponding coastal wetlands, no published data are available for the levels of phenolic compounds. Thus, this work aimed to investigate the levels of phenolic compounds in sediments of a heavily polluted coastal wetland (Lake Maryut, Egypt). For that purpose, a method was optimized for the extraction and detection of chlorophenols, methylphenols, and nitrophenols in sediments using GC-MS. Sediments were extracted with 0.1 M NaOH/methanol by sonication. Cleanup of sediment extracts using liquid-liquid extraction and SPE was found important to remove most of the interfering co-extracts. The proposed analytical methodology was validated by analysis of matrix spikes. Detection limits were 0.063-0.694 μg/kg dw for sediments. Good recoveries (70-110%) and precision values (RSD < 20%) were obtained from the fortification experiments at the parts per billion level in sediments. The method was applied to investigate the level of contamination with phenols in 19 sediment samples from Lake Maryut. Results revealed that higher concentrations were observed in the main basin (MB) of Lake Maryut affected by the discharge of effluents from a primary wastewater treatment plant, direct discharge of industrial effluents, domestic wastes, and agricultural effluents from Qalaa Drain (QD). Chlorophenols (CPs) were the major group detected in the lake sediments followed by methylphenols (MPs) and nitrophenols (NPs). CPs were dominated by 2-, 4-, and 3-chlorophenols. Concentrations of CPs were higher at the north and northwestern parts of the MB indicating the influence of industrial effluents discharged into the lake. On the other hand, higher concentrations of NPs were observed at the south and southwestern parts of the MB, which is subjected to the discharge of agricultural and domestic effluents via QD. Results of the risk assessment revealed that phenol, cresols, 2,4-dinitrophenol, 4-NP, 2-CP, 2,3,4,6-tetrachlorophenol and 2,4-dimethylphenol are contaminants of concern and that adverse ecological effects could possibly occur to benthic species from the exposure to these pollutants in Lake Maryut and thus phenols should be included in monitoring and pollution prevention programs in the Egyptian aquatic environment affected by anthropogenic activities.

The electrochemical detection of 4-chlorophenol at gold electrodes modified with different phthalocyanines

Because of their toxicity to humans and their tendency to bioaccumulate in the food chain, the detection of chlorophenols has been investigated intensively. This paper compares the oxidation of 4-chlorophenol on a bare gold electrode to its detection on gold electrodes electrochemically modified with either cobalt(II) tetrasulphonated phthalocyanine (CoTSPc) or 3,4′,4″,4‴-copper(II) tetrasulphonated phthalocyanine (CuTSPc). Results show that the electrochemical behaviour of 4-chlorophenol depends on the molecular structure of the phthalocyanine thin film layers on the gold surface. In addition, the influence of the coordinating properties of the phthalocyanines on the sensitivity of the measurement and the fouling of the electrode material is discussed.

Fluorometric Detection of p-Chlorophenol by ZnTPP-Intercalated Dialkyl Ammonium Smectite

Abstract Zn(II) tetraphenylporphyrin (ZnTPP)-intercalated dialkyl ammonium smectite was applied to the condensation and detection of chlorophenols in aqueous medium. ZnTPP and p-chlorophenol found to form a stable porphyrin-quinone dyad in micelles of dialkyl ammonium ion, accompanied with color-change and fluorescence quenching of ZnTPP. As a result, sub-ppm to ppm order of p-chlorophenol in water can be detected by the fluorescence quenching.

Development of the Infrared Hollow Waveguide Sampler for the Detection of Chlorophenols in Aqueous Solutions

A method based on the infrared hollow waveguide sampler was developed for sensing chlorophenols in aqueous solutions. This sampler was constructed by coating a suitable hydrophobic film onto the inner surface of an infrared hollow waveguide. By passing the aqueous solution through the hollow waveguide sampler, analytes can be absorbed into the hydrophobic layer. The adsorbed analytes can be sensed later by using Fourier transform infrared spectrometry. Six hydrophobic polymers were investigated for their performance in conjunction with the infrared hollow waveguide sampler for the detection of chlorophenols. Results indicated that poly(acrylonitrile-co-butadiene) was a most suitable hydrophobic material for absorption of chlorophenols in aqueous solutions. To further increase the detection sensitivity, factors such as sampling flow rate, sampling time, and thickness of the hydrophobic film were also investigated. Results indicated that the infrared signals were similar in the examined flow rates (2-30 mL/min), but that a higher flow rate tended to produce a higher analytical signal. Fast detection speed was an advantage of this method for the detection of chlorophenols, and the sampling/detection time can be <10 min. In addition, analytical signals were nearly proportional to the thickness of the hydrophobic film coating the inside of the hollow waveguide. With the optimal conditions found in this work, detection limits based on 3 times the peak-to-peak noise level were around 300 ppb for the chlorophenols examined. A high degree of linearity in the standard curves was also observed for this method in the concentration range of 10-100 ppm. The typical regression coefficients were >0.994 for the chlorophenols examined.

Analytical Currents: CE detection of chlorophenols

Analytical Currents: CE detection of chlorophenols

Liquid Chromatographic Retention Behavior and Separation of Chlorophenols on a -Cyclodextrin Bonded-Phase Column, Part II. Monoaromatic Chlorophenols: Separation

The liquid chromatographic separation of 19 monoaromatic chlorophenols on a beta-cyclodextrin bonded-phase column is investigated in both an isocratic and a gradient elution mode. Even though the isocratic mode can be employed for the separation of the member components of each category of chlorophenols (e.g., mono-, di-, etc.), significant overlaps between the retention times of the various categories prevent the separation of all chlorophenols on a single chromatogram. Gradient elution can be used, however, for the separation of 15 of the 19 chlorophenol isomers. The unique features of gradient elution as applied to beta-cyclodextrin bonded-phase columns are discussed. The detection of chlorophenols with UV and electrochemical methods is also discussed and the two are compared.