Phenols In Environmental Water Samples Research Articles

Dispersive liquid-liquid microextraction based on a new hydrophobic deep eutectic solvent for the determination of phenolic compounds in environmental water samples.

Dispersive liquid-liquid microextraction has garnered increasing attention in sample preparation due to its rapid and efficient extraction process. In this study, a new terpineol-based hydrophobic deep eutectic solvent was firstly synthesized by mixing α-terpineol with 1-octanoic acid, and then applied to analysis of phenols from water samples by dispersive liquid-liquid microextraction combined with high-performance liquid chromatography and diode array detection. Infrared spectroscopy indicated that hydrogen bonding was responsible for the formation of deep eutectic solvent between α-terpineol and 1-octanoic acid. After optimization of several parameters, such as the type and volume of deep eutectic solvent and the disperser, pH and ionic strength of sample solution, the developed method exhibited excellent extraction performance to the phenols with the enrichment factors from 27 to 32. Good linearity was acquired ranging from 5 to 5000μg/L, and detection of limits of the proposed method for the phenols ranged from 0.15 to 0.38μg/L. The recoveries measured by spiked samples at three concentration levels ranged from 81.6 to 99.3%, and precision was found with intra- and inter-day relative standard deviations less than 8.7 and 9.2%, respectively. Finally, the proposed method was successfully applied to the determination of the phenols in environmental water samples.

Rapid synergistic cloud point extraction for simultaneous determination of five polar phenols in environmental water samples via high performance liquid chromatography with fluorescence detection

A novel method was established for preconcentration and determination of the following five polar phenolic compounds: phenol, o-, m-, and p-cresol and 2,4-dimethylphenol. After separating and enriching the analytes by rapid synergistic cloud point extraction (RS-CPE), high performance liquid chromatography (HPLC) was carried out, and the components in surfactant-rich phase supernatant were detected fluorometrically. N-Pentanol, an alcohol with high polarity and rapid cloud point reduction effect, was used as the synergistic reagent, and the straight chain non-ionic surfactant Tergitol 15-S-7 was selected as the extractant. The pH, surfactant, salt concentration, revulsant and synergistic reagent were optimized. Under the optimum conditions, the correlation coefficients among target substances were all>0.998. The relative standard deviation range was 1.7%–5.0%, and the detection limit range was 0.061–0.166 μg/L. The proposed method is simple, economical, highly efficient and sensitive. It was successfully applied to the extraction and determination of polar phenolic compounds in environmental water samples, and the recoveries ranged from 85.6% to 108%.

Polydopamine modified ordered mesoporous carbon for synergistic enhancement of enrichment efficiency and mass transfer towards phenols

Integrating the steps of direct carbonization, removal of silica and polymerization of dopamine, four ordered mesoporous carbons (OMCs) doping with different constituents were prepared and characterized successfully, which were proved to possess similar ordered mesopore structure, high surface area and different hydrophilic properties. Subsequently, a series of pollutants were selected as target analytes to investigate the enrichment capacities of as-prepared OMCs based on the technique of solid phase microextraction (SPME). It was found that the OMC modified with polydopamine (OMC@PDA) demonstrated outstanding performance towards phenols, since its hydrophilicity was enhanced by PDA. Moreover, two extraction modes were employed to study the extraction process, including headspace and direct immersion. The synergistic enhancement effect of enrichment efficiency and mass transfer towards phenols using the OMC@PDA-coated fiber was demonstrated in the mode of direct immersion. To realize the target of high sensitivity, the OMC@PDA-coated fiber was coupled with the gas chromatography-mass spectrometry (GC-MS) after optimizations to develop analytical method. Wide linear range (5–5000 ng L−1), low detection limits (0.08–0.38 ng L−1) and excellent reproducibility made the developed method feasible for the determinations of trace phenols in environmental water samples.

Ionic liquid-based headspace in-tube liquid-phase microextraction coupled with capillary electrophoresis for sensitive detection of phenols.

An ionic liquid-based headspace in-tube liquid-phase microextraction (IL-HS-ITLPME) in-line coupled with capillary electrophoresis (CE) is proposed. The method is capable of quantifying trace amounts of phenols in environmental water samples. In the newly developed method, simply by placing a capillary injected with IL in the HS above the aqueous sample, volatile phenols were extracted into the IL acceptor phase in the capillary. After extraction, electrophoresis of the phenols in the capillary was carried out. Extraction parameters such as the extraction time, extraction temperature, ionic strength, volume of the sample solution and IL types were systematically investigated. Under the optimized conditions, enrichment factors for four phenols were from 1510 to 1985. The proposed method provided a good linearity, low limits of detection (below 5.0ng mL-1 ), and good repeatability of the extractions (RSDs below 6.7%, n=6). This method was then utilized to analyze two real environmental samples of Xiaoxi Lake and tap water, obtaining acceptable recoveries and precisions. Compared with the usual HS-ITLPME for CE, IL-HS-ITLPME-CE is a simple, low-cost, fast and environmentally friendly pre-concentration technique. This article is protected by copyright. All rights reserved.

Sensitive determination of typical phenols in environmental water samples by magnetic solid-phase extraction with polyaniline@SiO2 @Fe as the adsorbents before HPLC.

A novel magnetic core-shell material polyaniline@SiO2 @Fe (PANI@SiO2 @Fe) has been successfully synthesized and investigated as an effective adsorbent for the magnetic solid-phase extraction of typical endocrine disrupting compounds such as bisphenol A, tetrabromobisphenol A, and 4-nonylphenol from water samples. The morphology of the as-prepared PANI@SiO2 @Fe was characterized by transmission electron microscopy and X-ray diffraction. The main parameters that influenced the enrichment performance such as the kind of eluent, amount of adsorbent, volume of eluent, adsorption time, elution time, ionic strength, pH, concentration of humic acid, and sample volume were investigated. Under the optimal conditions, a good linear relationship was found in the range of 0.05-100μg/L for bisphenol A, 0.05-300μg/L for tetrabromobisphenol A, and 0.05-250μg/L for 4-nonylphenol, respectively. The correlation coefficients are all above 0.995. The limits of detection were in the range of 0.009-0.04μg/L, and precisions were under 3.73% (n=6). The real water analysis indicated that the spiked recoveries were in the range of 92.9-98.9% (n=3). All these results indicated that the developed method was an efficient tool for the analysis of bisphenol A, tetrabromobisphenol A, and 4-nonylphenol.

Multiple-helix cobalt(II)-based metal-organic nanotubes on stainless steel fibers for solid-phase microextraction of chlorophenol and nitrophenols from water samples

The high performance solid-phase microextraction (SPME) of polar phenols from aqueous matrices is a challenge due to the strong interaction between water molecules and polar phenols. The authors describe the fabrication of stainless steel fibers coated with multiple helix 3D metal-organic nanotubes via physical adhesion, and their application to the SPME of 2-chlorophenol, 2-nitrophenol, 2,4-dichlorophenol, 4-chloro-3-methylphenol and 2,4,6-trichlorophenol from water samples. GC/MS was used for sample quantification and detection. Box-Behnken design was adopted to optimize the experimental conditions through response surface methodology. The fibers display good thermal stability (~400 °C), high enrichment factors (418–1874), excellent repeatability (4.31%–8.37%), wide linear range (0.5–1000 ng⋅L−1) and low limits of detection (0.07–0.18 ng⋅L−1) for the phenols. This method was successfully applied to the analysis of phenols in environmental water samples.

Preparation and Application of Polyimide Coated Stir Bar for Extraction of Phenols in Environmental Water Samples

Abstract A polyimide coated stir bar for sorptive extraction (SBSE) was prepared by immersion precipitation method and evaluated by using 5 phenols and chlorinated phenols as model samples. The highest extraction efficiency was achieved among all commercial extraction phases of SBSE reported. Experimental parameters including stirring speed, ionic strength, extraction temperature, extraction time, desorption temperature and time were optimized. Under the optimal conditions such as 100 mL of sample, 30% NaCl, extraction time of 30 min, stirring speed of 800 rpm and extraction temperature of 25 °C, the target compounds were recovered by thermal desorption at 300 °C for 4 min. More than two orders of magnitude of linearity were obtained (R ≥ 0.9995). LOQs (S/N = 10) were 0.028–0.123 μg L−1, and RSDs were in the range of 1.6%–9.7%. The polyimide SBSE coupled with gas chromatography-mass spectrometry was applied to the extraction and analysis of phenols in real samples, including tap water, sea water, and waste water. It was found that the polyimide SBSE showed high selectivity towards polar compounds and high thermostability up to 350 °C.

Polydimethylsiloxane/covalent triazine frameworks coated stir bar sorptive extraction coupled with high performance liquid chromatography-ultraviolet detection for the determination of phenols in environmental water samples

In this work, covalent triazine frameworks (CTFs) were introduced in stir bar sorptive extraction (SBSE) and a novel polydimethylsiloxane(PDMS)/CTFs stir bar coating was prepared by sol–gel technique for the sorptive extraction of eight phenols (including phenol, 2-chlorophenol, 2-nitrophenol, 4-nitrophenol, 2,4-dimethylphenol, p-chloro-m-cresol and 2,4-dichlorophenol, 2,4,6-trichlorophenol) from environmental water samples followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. The prepared PDMS/CTFs coated stir bar showed good preparation reproducibility with the relative standard deviations (RSDs) ranging from 3.5 to 5.7% (n=7) in one batch, and from 3.7 to 9.3% (n=7) among different batches. Several parameters affecting SBSE of eight target phenols including extraction time, stirring rate, sample pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.08–0.30μg/L. The linear range was 0.25–500μg/L for 2-nitrophenol, 0.5–500μg/L for phenol, 2-chlorophenol, 4-nitrophenol as well as 2,4-dimethylphenol, and 1–500μg/L for p-chloro-m-cresol, 2,4-dichlorophenol as well as 2,4,6-trichlorophenol, respectively. The intra-day relative standard deviations (RSDs) were in the range of 4.3–9.4% (n=7, c=2μg/L) and the enrichment factors ranged from 64.9 to 145.6 fold (theoretical enrichment factor was 200-fold). Compared with commercial PDMS coated stir bar (Gerstel) and PEG coated stir bar (Gerstel), the prepared PDMS/CTFs stir bar showed better extraction efficiency for target phenol compounds. The proposed method was successfully applied to the analysis of phenols in environmental water samples and good relative recoveries were obtained with the spiking level at 2, 10, 50μg/L, respectively.

Carboxylated solid carbon spheres as a novel solid-phase microextraction coating for sensitive determination of phenols in environmental water samples

The high performance separation and enrichment of polar phenols from aqueous matrices is often difficult due to the strong interactions between phenols and water. In this paper, carboxylated solid carbon spheres (SCSs-COOH) were, for the first time, used as a novel coating material in the solid-phase microextraction (SPME) of polar phenols at ultra-trace levels in environmental water samples. Gas chromatography coupled with tandem mass spectrometry (GC–MS/MS) was applied for sample quantification and detection. The novel SCSs-COOH-coated fiber exhibited good thermal stability (>330°C) and higher extraction efficiency than commercial fibers in the extraction of phenols. The Plackett–Burman design was employed to optimize the extraction factors affecting the extraction efficiency through a response surface methodology. A possible phenol extraction mechanism enabled by the SCSs-COOH-coated fiber is proposed. Under the optimized conditions, low detection limits (0.26–2.63ngL−1), a wide linear range (1–1000ngL−1), good repeatability (2.00–9.02%, n=5) and excellent reproducibility (2.08–8.55%, n=3) were achieved. The developed method was validated against several environmental water samples, with satisfactory results being obtained each case.

Evaluation of Fe3O4@SiO2–MOF-177 as an advantageous adsorbent for magnetic solid-phase extraction of phenols in environmental water samples

Metal–organic frameworks (MOFs), a novel class of hybrid inorganic–organic materials, possess high surface area, good thermal stability and selectivity, and thus have great potential for use as sorbent materials. MOF-177 is attractive for its large pores, high adsorptivity and selectivity, which has rarely been used in analytical science. Herein a facile magnetization of MOF-177 for rapid magnetic solid phase extraction of phenols from environmental water samples was studied, with analysis using gas chromatography-mass spectrometry. The magnetization of MOF-177 microcrystals as well as solid-phase extraction (SPE) of phenols was achieved simultaneously by mixing MOF-177 and Fe3O4@SiO2 microparticles in the water sample under sonication. Under the optimized conditions, the developed method showed good linearity within the range of 1–200 μg L−1, low detection limits (16.8–208.3 ng L−1) and quantitation limits (56.0–694.2 ng L−1). The recoveries are between 83.3 and 108.7% with the spiked level of 25 μg L−1. The results demonstrated that the Fe3O4@SiO2–MOF-177 magnetic microspheres are promising sorbents in the MSPE field in environmental samples.

Chitosan-capped silver nanoparticles as a highly selective colorimetric probe for visual detection of aromatic ortho-trihydroxy phenols

We reported a new application of silver nanoparticles (NPs) for the visual sensing of aromatic polyphenols, such as gallic acid, pyrogallol and tannic acid, which is based on the intensified plasmon absorbance signals and visual changes from yellow to orange due to hydrogen-bonding recognition and subsequent catalytic oxidation of the target phenols by chitosan-capped AgNPs (Ch-AgNPs). The Ch-AgNPs are generated by the well-known reaction of AgNO3 with NaBH4 and stabilized with chitosan which is a polysaccharide biopolymer with excellent dispersive properties and stability in aqueous media. After optimizing some experimental conditions, a very simple and facile sensing system has been developed for the detection of gallic acid, pyrogallol and tannic acid in water samples. The proposed system promises high selectivity toward gallic acid, pyrogallol and tannic acid, and other phenolic compounds including p-aminobenzoic acid, pentachlorophenol, 2,4,6-trinitrophenol, 2,4-dinitrophenol, p-nitrophenol, 1-naphthol, β-naphthol, p-aminophenol, catechol, hydroquinone, m-dihydroxybenzene, phloroglucin and phenol could not induce a color change even at 0.1 mM. The outstanding selectivity property of the proposed method for gallic acid, pyrogallol and tannic acid resulted from the Ch-AgNPs-mediated reduction of Ag(+) by the target phenols. Also, a wide linear response range was obtained for the three targets. The linear response ranges for gallic acid, pyrogallol, and tannic acid were from 1 × 10(-5) to 1 × 10(-3) M, 1 × 10(-5) to 1 × 10(-2) M and 1 × 10(-6) to 1 × 10(-4) M with a respective detection limit (DL) of 1 × 10(-5), 1 × 10(-5), and 1 × 10(-6) M. The proposed method was successfully applied to detect target phenols in environmental water samples. Furthermore, because the color change from yellow to orange is observable by the naked eye, it is easy to realize visual detection of the target phenols without any instrumentation or complicated design. The experimental results reported here open up an innovative application of the catalytic reactivity of AgNPs.

New monolithic stir-cake-sorptive extraction for the determination of polar phenols by HPLC

A novel porous monolith has been prepared and used as a sorbent in stir-cake-sorptive extraction (SCSE). The monolithic material was prepared by in-situ copolymerization of allyl thiourea (AT) and divinylbenzene (DB) in the presence of dimethylformamide as a porogen solvent. To optimize the polymerization conditions, different monoliths with different ratios of functional monomer to porogenic solvent were prepared, and their extraction efficiency was investigated in detail. The monolith was characterized by elemental analysis, scanning electron microscopy, mercury intrusion porosimetry, and infrared spectroscopy. Analysis of polar phenols in environmental water samples by a combination of ATDB-SCSE and HPLC with diode-array detection was selected as a model for the practical application of the new sorbent. Several extraction conditions, including extraction and desorption time, pH, and ionic strength of the sample matrix were optimized. The results showed that the new monolith had high affinity for polar phenols and could be used to extract them effectively. Under the optimum conditions, low detection (S/N = 3) and quantification (S/N = 10) limits were achieved for the phenols, within the ranges 0.18-0.90 and 0.59-2.97 μg L(-1), respectively. The linearity of the method was good, and the method enabled simple, practical, and low-cost extraction of these analytes. The distribution coefficients between ATDB and water (K(ATDB/W)) were calculated for the phenolic compounds and compared with K(O/W). Finally, the proposed method was successfully applied to the determination of the compounds in three environmental water samples, with acceptable recovery and satisfactory repeatability.

Flow injection analysis of volatile phenols in environmental water samples using CdTe/ZnSe nanocrystals as a fluorescent probe

On the basis of flow injection analysis technology, a simple, accurate, and sensitive method has been developed for the determination of volatile phenols in environmental water samples by using CdTe/ZnSe nanocrystals as a fluorescent probe. The influences of coexisting metal ions and volatile phenol substitutes were also investigated. The method developed for analysis of volatile phenols displayed very good linearity in the range from 1.0 × 10(-8) to 4.0 × 10(-7) g L(-1), with a correlation coefficient greater than 0.995 and a detection limit down to 2.7 × 10(-9) g L(-1) (signal-to-noise ratio 3). The proposed method was successfully applied to determine the content of volatile phenols in environmental water samples, and the quantitative recoveries were 93.4-106.1%. A possible reaction mechanism for the quenching of fluorescence is discussed using UV-vis absorption spectra, fluorescence spectra, and time-resolved luminescence spectra of volatile phenols obtained by titrating a CdTe/ZnSe nanocrystal aqueous solution and zeta potential data.

Determination of phenols in environmental water samples by two-step liquid-phase microextraction coupled with high performance liquid chromatography

In this work, a two-step liquid-phase microextraction (LPME) method was presented for the extraction of phenols in environmental water samples. Firstly, the polar phenol in water samples (donor phase) was transferred to 1-octanol (extraction mesophase) by magnetic stirring-assisted LPME. Subsequently, target analytes in the 1-octanol was back extracted into 0.1mol/L sodium hydroxide solution (acceptor phase) by vortex-assisted LPME. By combination of the two-step LPME, the enrichment factors were multiplied. The main features of this two-step LPME for phenols lie in the following aspects. Firstly, the extraction can be accomplished within relatively short time (ca. 20min). Secondly, it was compatible with HPLC analysis, avoiding derivatization step that is generally necessary for GC analysis. Thirdly, high enrichment factors (296–954 fold) could be obtained for these analytes. Under the optimized conditions, the linearities were 10–1000, 1–500, 1–500, 5–500 and 1–500ng/mL for different phenols with all regression coefficients higher than 0.9985. The limits of detection were in the range from 0.3 to 3.0ng/mL for these analytes. Intra-and inter-day relative standard deviations were below 7.6%, indicating a good precision of the proposed method.

Preparation of hydrophilic C18 material and its application for solid phase extraction of phenols in water

A C18 monolithic material with a hydrophilic character was obtained by copolymerizing stearyl methacrylate (SMA) and a hydrophilic monomer poly (ethylene glycol) methyl ether methacrylate (PEGMEA) with porogen of 1-propanol/1,4-butanediol, and the resulting material was used for solid phase extraction (SPE) of phenols in water sample. Several parameters, including the proportion of the porogen, the pH value, the eluent species and the eluent volume during the extraction were investigated. Under the optimized experimental conditions, the linear calibration curves of five phenols were obtained in the ranges of 0.5-10 mg/L, the limits of detection (LODs) ranged from 0.16-0.47 mg/L. The new hydrophilic C18 material was successfully applied to analyze real environmental water samples with spiked recoveries in the range of 64.33%- 92.14% with relative standard deviations (RSDs) of 4.2%-6.4% (n = 3). The new hydrophilic material indicates great reliability, and it also presented an excellent extraction efficiency for the trace polar phenols in environmental water samples.

On-line coupling of ionic liquid-based single-drop microextraction with capillary electrophoresis for sensitive detection of phenols

An ionic liquid-based single-drop microextraction (IL-SDME) procedure using IL as an extractant on-line coupled to capillary electrophoresis (CE) is proposed. The method is capable of quantifying trace amounts of phenols in environmental water samples. For the SDME of three phenols, a 2.40 nL IL microdrop was exposed for 10 min to the aqueous sample and then was directly injected into the capillary column for analysis. Extraction parameters such as the extraction time, the IL single-drop volume, pH of the sample solution, ionic strength, volume of the sample solution and the extraction temperature were systematically investigated. Detection limits to three phenols were less than 0.05 μg mL −1, and their calibration curves were all linear ( R 2 ≥ 0.9994) in the range from 0.05 to 50 μg mL −1. And enrichment factors for three phenols were 156, 107 and 257 without agitation, respectively. This method was then utilized to analyze two real environmental samples from Yellow River and tap water, obtaining satisfactory results. Compared with the usual SDME for CE, IL-SDME–CE is a simple, low-cost, fast and environmentally friendly preconcentration technique.

Hollow fiber membrane supported thin liquid film extraction for determination of trace phenoxy acid herbicides and phenols in environmental water samples

Traces of phenoxy acid herbicides and phenols were determined in environmental water samples by high performance liquid chromatography (HPLC) coupled to thin liquid film extraction (TLFE). A TLFE sampling device was prepared by dipping pieces of a polypropylene microporous hollow fiber membrane into dihexyl ether (containing 10% tri-n-octylphosphine oxide as carrier) for a few minutes to impregnate the pores of the hollow fiber wall. Extraction of analytes takes place from the outer aqueous phase into the immobilized solvent. After extraction the removal of the organic solvent was accomplished with a few µl of methanol which was used for HPLC analysis. Enrichment factors as high as 446 were obtained for the target compounds. The method provided detection limits as low as 0.4–1.2 µg L−1, good repeatability (the RSD ranging from 2.1 to 6.3%, n = 5) and a linear range from 2 to 200 µg L−1 for the target compounds. Real sample analysis showed recoveries between 84.6% and 112% for all compounds investigated.

Sensitive determination of phenols in environmental water samples with SPE packed with bamboo carbon prior to HPLC

Bamboo carbon, an inexpensive, readily available material, has attracted great attention in recent years because of adsorptive properties. In this paper, the potential of bamboo carbon as a SPE adsorbent for the determination of phenols, was investigated. Phenols are important environmental contaminants that may adversely affect human health. Parameters influencing extraction efficiency, including type of eluent, eluent volume, amount of adsorbent, as well as sample pH, volume, and flow rate were investigated and optimized. The optimized results exhibited excellent linear relationships between peak area and phenol concentrations over the range of 2.0-100 ng/mL, with precision between 2.2-7.2%. The LODs were 0.06-0.4 ng/mL for the eight phenols tested. The proposed method has been successfully applied to the analysis of several real-world environmental water samples. These results indicate that bamboo carbon may be used as a novel SPE adsorbent for the concentration and determination of phenols in real environmental water samples.

Determination of phenols in environmental water samples by ionic liquid‐based headspace liquid‐phase microextraction coupled with high‐performance liquid chromatography

Headspace liquid-phase microextraction (HS-LPME) has been applied to efficient enrichment of phenols such as 2-nitrophenol, 4-chlorophenol, 2,4-dichlorophenol, and 2-naphthol from water samples based on 1-butyl-3-methylimidazolium hexafluorophosphate ([C4MIM][PF6]) as an extractant. Some parameters that may influence HS-LPME were investigated. The linear range was in the range of 0.5-100 microg/L, and the enrichment factors and repeatability (RSD, n = 6) of the proposed method were in the range of 17.2-160.7 and 5.4-8.9%, respectively. The detection limit for each analyte ranged from 0.3 to 0.5 microg/L. Complex matrices of environmental water samples had a small effect on the enrichment, and this problem could be resolved by the addition of sodium ethylene diamine tetraacetate (EDTA) into the samples. The spiked recoveries were in the range of 89.4-114.2%. All these facts demonstrated that the proposed method, with merits of low cost, simplicity, and easy operation, would be a competitive alternative procedure for the determination of such compounds at trace level.