Solid-phase Extraction Of Phenols Research Articles

Solid-phase extraction of phenols using UiO-66-NH2 metal–organic framework coated frits

Metal-organic frameworks have shown a great potential as adsorbents for analytical sample preparation. However, there is currently a shortage of straightforward and efficient methods that allow the integration of metal–organic frameworks onto low-pressure flow-through supports to serve this purpose effectively. This is limiting the further development of metal–organic framework applications as sorbents for cartridge-based solid-phase extraction. Herein, a simple strategy to incorporate metal–organic frameworks on commercial solid-phase extraction frits using polyvinylidene difluoride as polymer binder is presented. The performance of the prepared metal–organic framework-coated frits was evaluated using immobilized UiO-66-NH2 nanoparticles as a model metal–organic framework for the extraction and preconcentration of bisphenol A, 4-tert-octylphenol, 4-n-nonylphenol, 4-cumylphenol, and 4-octylphenol as model analytes. Under the optimal solid-phase extraction conditions, limits of detection were ranging from 0.04 μgL−1 to 0.67 μgL−1. RSDs for batch-to-batch reproducibility were in the range of 3.1 %-5.8 % for three metal–organic framework-coated frits prepared on different days. Analyte recoveries for spiked samples ranged between 94 % and 109 % for tap water, and 87 %-110 % for bottled drinking water. The resulting metal–organic framework-coated frits are directly fitted onto commercial solid-phase extraction cartridges, and the subsequent extractions can be carried out without the need for additional packed particles, or frits. The developed approach enables the development of analytical methods based on solid-phase extraction in cartridge format with no limitations regarding the particle size and shape of the selected sorbent.

Preparation of acidity-sensitive N-isopropylacrylamide and methacrylic acid copolymer monolithic column for the pipette tip solid phase extraction of phenols

An acidity-sensitive poly(N-isopropylacrylamide-methyl acrylic acid-co-divinyl- benzene) monolith was prepared in situ in a pipette tip for solid phase extraction of phenol, m-cresol, o-nitrophenol, 2,4-dichlorophenol and p-tert-butylphenol. The monolith was characterized by FT-IR, BET (surface area = 266.56 m2/g) and thermogravimetric analysis (thermally stable up to 350 °C). The introduction of methyl acrylic acid enhanced the stability in the strong alkaline condition. The adsorption experiments and density function theory calculations indicated NIPAM was the main adsorption sites and the adsorption mechanism of phenol on the monolith was hydrophobic interaction, H-bond interaction, C − H···π interaction of isopropyl group of NIPAM with the phenyl group of phenols. Based on these features and under the optimal extraction conditions, a pipette tip solid phase extraction coupled to high-performance liquid chromatography with ultraviolet detection method was developed for the determination of 5 phenols in the diffusion of polycarbonate cups. Due to the usage of 0.1 M NaOH as the eluent, the method presented selectivity for phenols based on the acidity-sensitive of the monolith. Wide linear range (0.6–200 µg/L), low detection limits (0.2–0.3 µg/L), good reproducibility (%RSD less than 9.8%) and satisfactory recoveries (86.3–114.1%) were obtained. The proposed method was suitable for quantitative analysis of phenollic in water samples.

Electrospun polystyrene nanofiber adsorbent for solid phase extraction of phenol as its quinoid derivative from aqueous solutions

In the present study, polystyrene nanofibers (PS NFs) were synthesized by electrospinning method and used as adsorbents in solid phase extraction of phenol from aqueous solutions. Phenol was reacted with 4-aminoantipyrine (4-AAP) reagent in presence of potassium hexacyanoferrate (III). The coloured product was extracted by solid phase extraction using electrospun synthesized polystyrene nanofibers and determined by UV-Vis spectrophotometer. At certain conditions of electrospinning process, the variables affecting the solid phase extraction efficiency were studied and optimized. Under the optimized conditions, (sorbent mass: 0.025 g PS NF, sample flow rate: 2.5 mL min−1, eluent: acetone: NaOH 0.1 M (1:1 v/v)), the linear dynamic range (LDR) and limit of detection (LOD as 3 Sb/m) for extraction of phenol from 50 mL of aqueous solutions were determined as 15-2500 µg L-1 and 10 µg L-1, respectively. The precision (as RSD %) of the extraction method using the proposed adsorbent was lower than 7.6%. Finally, the applicability of the proposed method for the extraction of phenol from industrial aqueous samples was examined and satisfactory results were obtained.

Preparation of metal-organic framework MIL-101(Cr) incorporated polymer monolithic column for on-line solid-phase extraction of phenols

A metal-organic framework (MOF) MIL-101(Cr) incorporated polymer monolithic column was prepared, and a method was developed for the determination of 4-nitrophenol, 3-methylphenol, 2-nitrophenol and 2,4-dichlorophenol in water samples by on-line solid phase extraction (SPE) coupled with high performance liquid chromatography (HPLC). Effects of sample solution pH values, sample loading time, sample loading flow rates and desorption time on the on-line SPE of phenols were investigated. Under the optimized extraction conditions, large enhancement factors, wide linearity range, good precisions and low limits of detection were achieved. The results showed that the incorporation of MOFs in porous polymer monolith to fabricate MOF-incorporated monolith is one of the best ways to promote and expand the application of MOFs in on-line SPE.

On-line coupling of solid-phase extraction of phenols on porous graphitic carbon and LC separation on C18 silica gel column via subcritical water desorption

ABSTRACTAn approach to the on-line coupling of solid-phase extraction on porous graphitic carbon (PGC) column and high performance liquid chromatography (HPLC) separation on octadecyl silica column is proposed. The approach includes extraction of phenols from 10 ml of water sample on PGC column; desorption with subcritical water at 175°C, injection of the eluate to the HPLC column and separation at ambient temperature with acetonitrile–water eluent. Limits of detection for UV detection of phenols were 1–5 μg l−1, and analyte peaks were 20–50% narrower than for direct injection of 20 μl of sample.

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.

Solid Phase Extraction of Phenol on Zeolitic Material: Batch Sorption and Column Dynamics

The solid phase extraction of phenol using hydrothermal (CZBFA) and fusion synthesized zeolitic materials (FZBFA) were carried out by batch and column mode. The chemical composition and the functional groups of synthesized zeolitic materials were investigated by XRF and FTIR. The major zeolitic phases and morphology were identified by PXRD and SEM techniques. The isotherms were estimated for the nature of sorption of phenols on sorbents. Thermodynamics parameters exhibited the endothermic nature of sorption. The phenol sequestration is highest for FZBFA as compare to bentonite, mud, and resin sorbents but lower than the activated carbon. Desorption of phenol is highest for BFA with 0.5 M NaOH.

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.

The Solid Phase Extraction of Phenol and Chlorophenols by the Chemically Modified Polymeric Adsorbents with Porphyrins

The commercially available Amberlite XAD-2 and XAD-4 resins were modified with macrocyclic protoporphyrin IX (PPIX) or tetrakis(p-carboxyphenyl) porphyrin (TCPP) to enhance the adsorption capacity for phenol and chlorophenols. The chemically modified polymeric adsorbents (XAD-2+PPIX, XAD-2+TCPP, XAD-4+PPIX, and XAD-4+TCPP) were applied to the solid phase extraction as an adsorbent material for the preconcentration of phenol and chlorophenols in environmental waters. Generally, the synthesized adsorbents showed higher recoveries than underivatized adsorbents, XAD-2 and XAD-4, without matrix interferences. Especially, XAD-4+PPIX showed more than 90% recoveries for all compounds used in this study including hydrophilic phenol. The major factor for the increase of the adsorption capacity was the increase of <TEX>$\pi$</TEX>-<TEX>$\pi$</TEX> interaction between adsorbents and samples due to the introduction of the porphyrin molecule. However, the breakthrough volumes and recovery values of the XADs+TCPP columns were slightly decreased for the bulky chlorophenols such as TCP and PCP. Using molecular mechanics methods, the structures of TCPP and PPIX were compared with that of porphine, the parent molecule of porphyrin. Four bulky p-carboxyphenyl groups of TCPP were torsional each other, thus the molecular plane of TCPP were not on the same level. In conclusion, the decrease of breakthrough volumes and recovery values of XADs+TCPP columns for bulky phenols can be explained by the steric hindrance of the <TEX>$\pi$</TEX>-<TEX>$\pi$</TEX> interaction between porphyrin plane and the phenols.

Solid Phase Extraction of Phenol and Chlorophenols on Octadecylsilica and Amberlite XAD 2 Sorbents in the Presence of Cationic Surfactant

Solid phase extraction of mixtures of phenol 3 monochlorophenols, 4 dichlorophenols, 3 methyl-4-chlorophenol, 4 trichlorophenols, 2 tetrachlorophenols and pentachlorophenol was studied on octadecylsilica (Separon SGX C18) and Amberlite XAD 2 in the presence of hexadecyltrimethylammonium chloride (CTMA) in alkaline medium, and their efficiency for the preconcentration of phenols was compared. The HPLC on narrow bore octadecylsilica column was successfully used for the determination of phenols in methanol eluate, when gradient elution was applied with (36:65) methanol/phosphate buffer of pH 3.5 and methanol mobile phases, and a diode array detector was used for their evaluation.

Solid-Phase Extraction of Phenol and Chlorophenols in Water with a Chemically Modified Polymer-Supported Tetrakis(p-carboxyphenyl) Porphyrin (H2TCPP)

A chemically modified sorbent was evaluated as a preconcentration substrate in solid-phase extraction of phenol and chlorophenols. Tetrakis(p-carboxyphenyl) porphyrin (H2TCPP) was chemically bonded to porous polymeric XAD resins by ketone linkage. Breakthrough volumes, recovery values, and detection limits were determined. The synthesized sorbent showed higher recoveries in tap water than commercially available sorbents such as XAD-2 and XAD-4.

Effect of Surfactant Loading on the Extraction Properties of C-18 Bonded Silica used for Solid-Phase Extraction of Phenols

ABSTRACT A solid phase extraction (SPE) system has been modified with cationic surfactants and evaluated for extraction and preconcentration of trace phenolic compounds contaminants in water at low ppb concentrations. Cationic surfactants such as cetyl trimethyl ammonium bromide (CTAB) has been steadily adsorbed on the surface of C-18 bonded silica, and the ionized functional group of the surfactant can then act as an ion–exchange site to attract the ionized phenolic compounds from water samples. The method includes enrichment of the phenolic compounds by the surfactant-loaded solid phase extraction system, followed by elution of the analyte with methylene chloride and derivatization of the phenolic compounds with acetic anhydride. Thirty-two phenolic analytes were identified and quantitatively determined by this method; identification and quantification of the compounds is performed with GC/FID using 2-bromophenol as internal standard. SPME analysis with this method was linear over 3-6 orders of magnitude, with linear correlation coefficient (R2) greater than 0.96. Experimentally determined FID detection limits ranged from ∼30 ppt for methyl-substituted phenols to ∼0.1ppb for phenol and chloro-substituted phenols. We tested the influence of sample pH, the loading amount of surfactant on the solid phase, and the volume and matrixes of the sample were studied. Absolute recoveries from pure water spiked with 0.2 ppb phenolic compounds were 96 – 103%. The method has been applied to analysis of various natural waters, including ground water, lake water, seawater, and wastewater. Recoveries from ground water, lake water, seawater, and wastewater were 92 – 106%, 75 – 93%, 87 – 103%, 86 – 99%, respectively. Therefore, the new technique proved to be an excellent tool for trace enrichments of phenolic compounds at low ppb concentration of these analytes, from different natural water samples.

Evaluation of Chitin and Chitosan as a Sorbent for the Preconcentration of Phenol and Chlorophenols in Water

The evaluation of the applicability of chitin and chitosan as a sorbent material to solid phase extraction of phenol and chlorophenols was made by using high-performance liquid chromatography (HPLC). For the measurement of the adsorp-tive capabilities, adsorption isotherms as well as breakthrough curves were obtained by means of batch experiments or column experiments respectively. The increasing tendency of the amount of adsorption with the number of chlorine atom in phenol molecules was observed for both chitin and chitosan. The driving force of the interaction could be attributed to hydrogen bonding among electro-negative atoms in chitin, chitosan or chlorophenols.

Solid-phase extraction of phenols and pesticides in water with a modified polymeric resin.

A comparative study of a chemically modified polymeric resin which has a benzoyl group and several commercial sorbents, such as PLRP-S, Envi-chrom P and LIChrolut EN, for the solid-phase extraction of various phenolic compounds and pesticides was carried out. Selectivity and breakthrough volumes for these compounds with different sorbents were studied by coupling an on-line solid-phase extraction system with a modified liquid chromatograph equipped with a UV detector. After determining the chromatographic conditions, linearity range and detection limits, the method was applied to the determination of these compounds in drinking and surface water. For 25 ml of sample, the recovery was > 70% for all the compounds, except for 4-nitrophenol (62%), and detection limits were between 0.2 and 0.8 microgram I-1.

Use of the hyper-crosslinked polystyrene sorbents ?Styrosorb? for solid phase extraction of phenols from water

The analytical HPLC procedure for the quantitation of trace amounts of phenol and chlorophenols in aqueous media has been supplemented with the on-line preconcentration of phenols in a sorption cartridge packed with microporous hyper-crosslinked polystyrene. The cartridge is coupled in succession with a reversed-phase analytical column, which is operated isocratically in an aqueous acetonitrile eluent (1:1, v/v). Phenol concentrations down to 0.5 μg/l can be detected using a simple 254 nm UV detector.

Solid-phase extraction of phenols using membranes loaded with modified polymeric resins

Membranes impregnated with polystyrene-divinylbenzene (PS-DVB) or acetyl-PS-DVB resin beads were used for solid-phase extraction of ppm (w/w) concentrations of phenols from aqueous samples. A macro procedure uses 47 × 0.5 mm disks with 200–500 ml sample volumes at ca. 200 ml/min flow-rates. A smaller-scale procedure uses a thicker disk (3 mm) packed into a conventional solid-phase extraction column (7 mm I.D.). The retained phenols are eluted from the disk with organic solvent, and the individual phenols are determined quantitatively by GC or HPLC. Recoveries for 16 different phenols, including those included in the US Environmental Protection Agency list of priority pollutants, averaged 98% with a standard deviation of ± 2%.