Cationic Surfactants as Regulators in Paper Separation of 2‐Nitrophenol and 2,4,6‐Trinitrophenol in Water

The chemical pollutants 2‐nitrophenol (2‐NP) and 2,4,6‐trinitrophenol (2,4,6‐TNP) were studied for their separation from water by the paper capillary permeation adsorption technique by the use of the four cationic surfactants dodecyltrimethylammonium chloride (DTAC), tetradecyltrimethylammonium bromide (TTAB), cetyltrimethylammonium bromide (CTAB), cetylpyridinium chloride (CPC) as regulators. The effect of pH and the concentration of surfactant on the separatability have been investigated. A nearly 100% separatability was obtained for each pollutant at its optimum pH and surfactant concentration. It was shown that the separation was accomplished via surface adsorption onto the fibers of paper. The change in separatability at basic pH 11 with surfactant variety was analyzed. The result shows that the surfactant with a longer chain alkyl group is more effective for the separation of 2‐NP and the surfactants with 16 carbons in the long chain alkyl group are most effective. The surfactants with 12 carbons or more in the long alkyl group but containing no aromatic group such as pyridyl group are equally effective for accomplishing an efficient separation of 2,4,6‐TNP. Selective separation of 2‐NP from an admixture of 2‐NP plus 2,4,6‐TNP was attempted. The optimum surfactant for each pollutant was tested with seawater for removing the pollutant. The goal of this study is to search for an optimum cationic surfactant and optimum separation conditions for nitrophenols.     

Cetyltrimethylammonium Bromide as a Surface Modifier in Paper Separation of 2,4‐D and Silvex Herbicides from Aqueous Solutions

The paper capillary permeation adsorption (PCPA) separation of 2,4‐D and silvex herbicides from water by the addition of cetyltrimethylammonium bromide (CTAB) was studied. The effect of pH, CTAB concentration, and the type of PCPA treatment on separatability has been investigated. A nearly 100% separatability was obtained for each of 2,4‐D and silvex at pH values larger than 7 and 5, respectively. The separatability is greater than that without an addition of CTAB. It was confirmed that 2,4‐D and silvex are adsorbed as molecules on the fiber surface that contains ion pairs CTA⁺COO^? formed by the combination of CTA⁺ cations with the carboxyl groups bonded in the fiber surface.     

Dispersive liquid‐liquid microextraction coupled with pressure‐assisted electrokinetic injection for simultaneous enrichment of seven phenolic compounds in water samples followed by determination using capillary electrophoresis

Offline dispersive liquid‐liquid microextraction combined with online pressure‐assisted electrokinetic injection was developed to simultaneously enrich seven phenolic compounds in water samples, followed by determination using capillary electrophoresis, namely phenol, 4‐chlorophenol, pentachlorophenol, 2,4,6‐trichlorophenol, 2,4‐dichlorophenol, 2‐chlorophenol, and 2,6‐dichlorophenol. Several parameters affecting separation performance of capillary electrophoresis and the enrichment efficiency of pressure‐assisted electrokinetic injection and dispersive liquid‐liquid microextraction were systematically investigated. Under the optimal conditions, seven phenolic compounds were completely separated within 14 min and good enrichment factors were obtained of 61, 236, 3705, 3288, 920, 86, and 1807 for phenol, 4‐chlorophenol, pentachlorophenol, 2,4,6‐trichlorophenol, 2,4‐dichlorophenol, 2‐chlorophenol, and 2,6‐dichlorophenol, respectively. Good linearity was attained in the range of 0.1–200 μg/L for 2,4‐dichlorophenol, 0.5–200 μg/L for 4‐chlorophenol, pentachlorophenol, 2,4,6‐trichlorophenol, 2‐chlorophenol, and 2,6‐dichlorophenol, as well as 1–200 μg/L for phenol, with correlation coefficients (r) over 0.9905. The limits of detection and quantification ranging from 0.03–0.28 and 0.07–0.94 μg/L were attained. This two step enrichment method was potentially applicable for the rapid and simultaneous determination of phenolic compounds in water samples.     

The hydrogen‐bonded complex bis(tert‐butylammonium) 2,6‐dichlorophenolate 2,4‐dichlorophenol–2,4‐dichlorophenolate tetrahydrofuran disolvate containing a chiral R53(10) hydrogen‐bonded ring as a supramolecular synthon

A fixed hydrogen‐bonding motif with a high probability of occurring when appropriate functional groups are involved is described as a `supramolecular hydrogen‐bonding synthon'. The identification of these synthons may enable the prediction of accurate crystal structures. The rare chiral hydrogen‐bonding motif R₅³(10) was observed previously in a cocrystal of 2,4,6‐trichlorophenol, 2,4‐dichlorophenol and dicyclohexylamine. In the title solvated salt, 2C₄H₁₂N⁺·C₆H₃Cl₂O⁻·(C₆H₃Cl₂O⁻·C₆H₄Cl₂O)·2C₄H₈O, five components, namely two tert‐butylammonium cations, one 2,4‐dichlorophenol molecule, one 2,4‐dichlorophenolate anion and one 2,6‐dichlorophenolate anion, are bound by N—H…O and O—H…O hydrogen bonds to form a hydrogen‐bonded ring, with the graph‐set motif R₅³(10), which is further associated with two pendant tetrahydrofuran molecules by N—H…O hydrogen bonds. The hydrogen‐bonded ring has internal symmetry, with a twofold axis running through the centre of the 2,6‐dichlorophenolate anion, and is isostructural with a previous and related structure formed from 2,4‐dichlorophenol, dicyclohexylamine and 2,4,6‐trichlorophenol. In the title crystal, helical columns are built by the alignment and twisting of the chiral hydrogen‐bonded rings, along and across the c axis, and successive pairs of rings are associated with each other through C—H…π interactions. Neighbouring helical columns are inversely related and, therefore, no chirality is sustained, in contrast to the previous case.     

Field‐amplified sample injection combined with capillary electrophoresis for the simultaneous determination of five chlorophenols in water samples

A sensitive method of CZE‐ultraviolet (UV) detection based on the on‐line preconcentration strategy of field‐amplified sample injection (FASI) was developed for the simultaneous determination of five kinds of chlorophenols (CPs) namely 4‐chlorophenol (4‐CP), 2‐chlorophenol (2‐CP), 2,4‐dichlorophenol (2,4‐DCP), 2,4,6‐trichlorophenol (2,4,6‐TCP), and 2,6‐dichlorophenol (2,6‐DCP) in water samples. Several parameters affecting CZE and FASI conditions were systematically investigated. Under the optimal conditions, sensitivity enhancement factors for 4‐CP, 2‐CP, 2,4‐DCP, 2,4,6‐TCP, and 2,6‐DCP were 9, 27, 35, 43, and 43 folds, respectively, compared with the direct CZE, and the baseline separation was achieved within 5 min. Then, the developed FASI‐CZE‐UV method was applied to tap and lake water samples for the five CPs determination. The LODs (S/N = 3) were 0.0018–0.019 µg/mL and 0.0089–0.029 µg/mL in tap water and lake water, respectively. The values of LOQs in tap water (0.006–0.0074 µg/mL) were much lower than the maximum permissible concentrations of 2,4,6‐TCP, 2,4‐DCP, and 2‐CP in drinking water stipulated by World Health Organization (WHO) namely 0.3, 0.04, and 0.01 µg/mL, respectively, and thereby the method was suitable to detect the CPs according to WHO guidelines. Furthermore, the method attained high recoveries in the range of 83.0–119.0% at three spiking levels of five CPs in the two types of water samples, with relative standard deviations of 0.37–8.58%. The developed method was proved to be a simple, sensitive, highly automated, and efficient alternative to CPs determination in real water samples.     

Cetyltrimethylammonium Bromide as a Regulator in Paper Separation of Pentachlorophenol Herbicide and Methyl Orange Dye

An experimental investigation is presented for separation of pentachlorophenol (PCP) and methyl orange (MO) from an aqueous solution by use of cetyltrimethylammonium bromide (CTAB) as a regulator in the paper capillary permeation adsorption process (PCPA). The effects of pH, concentration of CTAB, and ionic strength on the separatability of the molecules were studied. The maximum separatability of nearly 100% PCP and MO was obtained in the optimum pH range 5–11 and 7–11, respectively. The ionic strength has an appreciable effect on separatability. The recovery of PCP and MO from paper by elution with acetone: isooctane solvent gradients was also studied. The selective separation of PCP and MO admixed in aqueous solution by a developed solvent elution technique was also reported. It was believed that PCP and MO were separated as their ion pairs with CTA cations by adsorption on the fiber surface.     

Simultaneous determination of haloanisoles and halophenols in water using in situ acylation combined with solid‐phase microextraction with gas chromatography and mass spectrometry

In this work, an in situ acylation combined with solid‐phase microextraction coupled to gas chromatography and mass spectrometry method has been developed for simultaneously determining haloanisoles (2,4,6‐trichloranisole, 2,4,6‐tribromoanisole), and their direct precursors (2,4,6‐trichlorophenol, 2,4,6‐tribromophenol) and indirect precursors (2‐chloropenol, 2,4‐dichlorophenol, 2‐bromophenol, 2,4‐dibromophenol) in water. The key parameters for the solid‐phase microextraction were determined by using Plackett–Burman screening and optimized by central composite optimization. Under optimal conditions, the eight compounds can be analyzed in a short time (33 min) with a strong linearity ranging from 2 to 200 ng/L (correlation coefficient greater than 0.996), showing good sensitivities with the limit of detection in a range of 0.23–0.91 ng/L and a limit of quantification of 0.77–3.03 ng/L, good repeatability (2.00–9.10%) and interday precision (1.67–11.3%). When environmental water samples were treated, the recoveries of target compounds were 75.5–127.3%, suggesting that the developed method could be applied in probing the origin of haloanisoles and monitoring halophenols and haloanisoles in natural waters at concentration levels of ng/L.     

Solid‐phase microextraction based on polyaniline doped with perfluorooctanesulfonic acid coupled to HPLC for the quantitative determination of chlorophenols in water samples

A porous and highly efficient polyaniline‐based solid‐phase microextraction (SPME) coating was successfully prepared by the electrochemical deposition method. A method based on headspace SPME followed by HPLC was established to rapidly determine trace chlorophenols in water samples. Influential parameters for the SPME, including extraction mode, extraction temperature and time, pH and ionic strength procedures, were investigated intensively. Under the optimized conditions, the proposed method was linear in the range of 0.5–200 μg/L for 4‐chlorophenol and 2,4,6‐trichlorophenol, 0.2–200 μg/L for 2,4‐dichlorophenol and 2–200 μg/L for 2,3,4,6‐tetrachlorophenol and pentachlorophenol, with satisfactory correlation coefficients (>0.99). RSDs were <15% (n = 5) and LODs were relatively low (0.10–0.50 μg/L). Compared to commercial 85 μm polyacrylate and 60 μm polydimethylsiloxane/divinylbenzene fibers, the homemade polyaniline fiber showed a higher extraction efficiency. The proposed method has been successfully applied to the determination of chlorophenols in water samples with satisfactory recoveries.     

Preparation of monolithic fibers for the solid‐phase microextraction of chlorophenols in water samples

Monolithic fibers were synthesized and applied for the solid‐phase microextraction and determination of chlorophenols in environmental water samples by coupling with HPLC. The fibers were prepared by copolymerization of vinylimidazole and ethylene dimethacrylate as functional monomer and cross‐linker, respectively. The effect of the preparation conditions of monolithic fibers on the extraction efficiencies was investigated in detail. Several characteristic techniques, such as elemental analysis, infrared spectroscopy, mercury‐intrusion porosimetry, and SEM were used to characterize the monolithic material. The effect of the extraction parameters, including desorption solvent, extraction and desorption time, pH values, and ionic strength in sample matrix on the extraction performance was investigated thoroughly. Under the improved extraction conditions, the linear ranges of 2‐chlorophenol, 2,4‐dichlorophenol and pentachlorophenol were 1.0–200 μg/L and 2.0–200 μg/L for 2,4,6‐trichlorophenol. The detection limits (S/N = 3) were in the range of 0.16–0.45 μg/L, the RSDs for intraday and interday precisions were <7.0%. Finally, the proposed method was successfully used to detect different environmental water samples. The recoveries of spiked water samples were ranged from 90.0 to 115%. At the same time, satisfactory repeatability was achieved with RSDs < 9.0%.     

Dispersive liquid–liquid microextraction of five chlorophenols in water samples followed by determination using capillary electrophoresis

Dispersive liquid–liquid microextraction (DLLME) coupled with CE was developed for simultaneous determination of five types of chlorophenols (CPs), namely 2‐chlorophenol (2‐CP), 4‐chlorophenol (4‐CP), 2,4‐dichlorophenol (2,4‐DCP), 2,6‐dichlorophenol (2,6‐DCP), and 2,4,6‐trichlorophenol (2,4,6‐TCP) in water samples. Several parameters affecting DLLME and CE conditions were systematically investigated. Under the optimized DLLME‐CE conditions, the five CPs were separated completely within 7.5 min and good enrichment factors were obtained of 40, 193, 102, 15, and 107 for 4‐CP, 2,4,6‐TCP, 2,4‐DCP, 2‐CP, and 2,6‐DCP, respectively. Good linearity was attained in the range of 1–200 μg/L for 2,4,6‐TCP, 2,4‐DCP, 2−300 μg/L for 4‐CP and 2‐CP, and 1−300 μg/L for 2,6‐DCP, with correlation coefficients (r) over 0.99. The LOD (S/N = 3) and the LOQ (S/N = 10) were 0.31−0.75 μg/L and 1.01−2.43 μg/L, respectively. Recoveries ranging from 60.85 to 112.36% were obtained with tap, lake, and river water spiked at three concentration levels and the RSDs (for n = 3) were 1.31–11.38%. With the characteristics of simplicity, cost‐saving, and environmental friendliness, the developed DLLME‐CE method proved to be potentially applicable for the rapid, sensitive, and simultaneous determination of trace CPs in complicated water samples.     

The Analysis of Chlorinated Phenol Solutions by Capillary Electrophoresis Coupled with Direct and Indirect Amperometric Detection Using a Boron‐Doped Diamond Microelectrode

Analysis of aqueous solutions containing chlorinated phenol pollutants was accomplished by capillary electrophoresis with direct and indirect amperometric detection using a boron‐doped diamond microelectrode. The microelectrode was prepared by (i) coating a thin film of boron‐doped polycrystalline diamond on a sharpened platinum wire (76‐μm diameter) and (ii) sealing the coated wire in a polypropylene pipet tip. The diamond microelectrode, used in end‐column detection, exhibited a low and stable background current with low peak‐to‐peak noise and good electrochemical activity for the pollutants without any conventional pretreatment. The electrode performance was evaluated in terms of the linear dynamic range, sensitivity, limit of quantitation, and response precision for the detection of several priority pollutants (2‐chlorophenol, 3‐chlorophenol, 4‐chlorophenol, 2,4‐dichlorophenol, 2,4,6‐trichlorophenol, and pentachlorophenol). The diamond microelectrode gave good detection figures of merit for these contaminants in the direct amperometric mode with no evidence of any electrode fouling. As an example, the concentration limit of quantitation for 2‐chlorophenol was 100 nM or 13 ppb (S/N=3) and the relative standard deviation of the peak height for 9 injections was 4.7±0.5% (est. 1.1 nL inj.). The separation efficiency was greater than 100 000 plates/m for all seven solutes. The microelectrode was also employed for the indirect detection of the chlorinated phenols. In this approach, which is useful for detecting electroinactive solutes, ferrocene carboxylic acid was added to the run buffer as the electrophore. Good detection figures of merit were also achieved for the separation and detection of 2‐chlorophenol, 3‐chlorophenol, and 2,4‐dichlorophenol in this mode, although the linear dynamic range was not as wide and the limit of quantitation was not as low as in direct amperometry. For example, the concentration limit of quantitation for these pollutants was in the mid micromolar range (1–10 ppm) with excellent response reproducibility of 3.2±0.8%, or less.     

Graphene oxide reinforced polymeric ionic liquid monolith solid‐phase microextraction sorbent for high‐performance liquid chromatography analysis of phenolic compounds in aqueous environmental samples

A graphene oxide reinforced polymeric ionic liquids monolith was obtained by copolymerization of graphene oxide doped 1‐(3‐aminopropyl)‐3‐(4‐vinylbenzyl)imidazolium 4‐styrenesulfonate monomer and 1,6‐di‐(3‐vinylimidazolium) hexane bihexafluorophosphate cross‐linking agent. Coupled to high‐performance liquid chromatography, the monolith was used as a solid‐phase microextraction sorbent to analyze several phenolic compounds in aqueous samples. Under the optimized extraction and desorption conditions, linear ranges were 5–400 μg/L for 3‐nitrophenol, 2‐nitrophenol, and 2,5‐dichlorophenol and 2–400 μg/L for 4‐chlorophenol, 2‐methylphenol, and 2,4,6‐trichlorophenol (R² = 0.9973–0.9988). The limits of detection were 0.5 μg/L for 3‐nitrophenol and 2‐nitrophenol and 0.2 μg/L for the rest of the analytes. The proposed method was used to determine target analytes in groundwater from an industrial park and river water. None of the analytes was detected. Relative recoveries were in the range of 75.5–113%.     

Facile preparation of multifunctional carbon nanotube/magnetite/polyaniline nanocomposite offering a strong option for efficient solid‐phase microextraction coupled with GC–MS for the analysis of phenolic compounds

The aim of this study was to synthesize a highly efficient organic–inorganic nanocomposite. In this research, the carbon nanotube/magnetite/polyaniline nanocomposite was successfully prepared through a facile route. Monodisperse magnetite nanospheres were prepared through the coprecipitation route, and polyaniline nanolayer as a modified shell with a high surface area was synthesized by an in situ growth route and characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction, and energy‐dispersive X‐ray spectroscopy. The prepared nanocomposite was immobilized on a stainless‐steel wire for the fabrication of the solid‐phase microextraction fiber. The combination of headspace solid‐phase microextraction using carbon nanotube/magnetite/polyaniline nanocomposite fiber with gas chromatography and mass spectrometry can achieve a low limit of detection and can be applied to determine phenolic compounds in water samples. The effects of the extraction and desorption parameters including extraction temperature and time, ionic strength, stirring rate, pH, and desorption temperature and time have been studied. Under the optimum conditions, the dynamic linear range was 0.01–500 ng/mL and the limits of detection of phenol, 4‐chlorophenol, 2,6‐dichlorophenol, and 2,4,6‐trichlorophenol were the lowest (0.008 ng/mL) for three times. The coefficient of determination of all calibration curves was more than 0.990.     

A poly (4‐vinylpridine‐co‐ethylene glycol dimethacrylate) monolithic concentrator for in‐line concentration‐capillary electrophoresis analysis of phenols in water samples

A poly(4‐vinylpridine‐co‐ethylene glycol dimethacrylate) monolith was synthesized in a capillary and constructed as a concentrator for the in‐line polymeric monolith microextraction coupling with capillary electrophoresis. The integrated system was then used for the simultaneous determination of five trace phenols (2‐nitrophenol, 3‐nitrophenol, 4‐nitrophenol, 2‐chlorophenol, and 2,4‐dichlorophenol) in water samples. The experimental parameters for in‐line solid‐phase extraction, such as composition and volume of the elution plug, pH of sample solution, and the time for sample loading were optimized. The sensitivity for the mixture of phenols (2‐nitrophenol, 3‐nitrophenol, 4‐nitrophenol, 2‐chlorophenol, and 2,4‐dichlorophenol) enhanced to 615–2222 folds at the optimum condition was compared to the sensitivity for a normal hydrodynamic injection in capillary electrophoresis. Linearity ranged from concentration of 10–500 ng mL^?1(R² > 0.999) for all five phenols with the detection limits of 1.3–3.3 ng mL^?1. In tap, snow and Yangtze River water spiked with 20 ng mL^?1 and 200 ng mL^?1, respectively, the recoveries of 84–105% were obtained. It has been demonstrated that this work has great potential for the analysis of phenols in genuine water samples.     

Simultaneous dispersive liquid–liquid microextraction based on a low‐density solvent and derivatization followed by gas chromatography for the simultaneous determination of chloroanisoles and the precursor 2,4,6‐trichlorophenol in water samples

Chloroanisoles, particularly 2,4,6‐trichloroanisole, are commonly identified as major taste and odor compounds in water. In the present study, a simple and efficient method was established for the simultaneous determination of chloroanisoles and the precursor 2,4,6‐trichlorophenol in water by using low‐density‐solvent‐based simultaneous dispersive liquid–liquid microextraction and derivatization followed by gas chromatography with electron capture detection. 2,4‐Dichloroanisole, 2,6‐dichloroanisole, 2,4,6‐trichloroanisole, 2,3,4‐trichloroanisole, and 2,3,6‐trichloroanisole were the chloroanisoles evaluated. Several important parameters of the extraction‐derivatization procedures, including the types and volumes of extraction solvent and disperser solvent, concentrations of derivatization agent and base, salt addition, extraction‐derivatization time, and temperature were optimized. Under the optimized conditions (80 μL of isooctane as extraction solvent, 500 μL of methanol as disperser solvent, 60 μL of acetic anhydride as derivatization agent, 0.75% of Na₂CO₃ addition w/v, extraction‐derivatization temperature of 25°C, without salt addition), a good linearity of the calibration curve was observed by the square of correlation coefficients (R²) ranging from 0.9936 to 0.9992. Repeatability and reproducibility of the method were < 4.5% and <7.3%, respectively. Recovery rates ranged from 85.2 to 101.4%, and limits of detection ranged from 3.0 to 8.7 ng/L. The proposed method was applied successfully for the determination of chloroanisoles and 2,4,6‐trichlorophenol in water samples.     

Magnetic chitosan functionalized with β‐cyclodextrin as ultrasound‐assisted extraction adsorbents for the removal of methyl orange in wastewater coupled with high‐performance liquid chromatography

Three types of choline chloride based deep eutectic solvents were prepared and used to modify magnetic chitosan. The adsorption capacity of the three deep‐eutectic‐solvent‐modified magnetic chitosan/carboxymethyl‐β‐cyclodextrin for removing methyl orange from wastewater was examined. The different deep eutectic solvents were used to strengthen the adsorption capacity of magnetic chitosan. Deep‐eutectic‐solvent‐modified magnetic chitosan/carboxymethyl‐β‐cyclodextrin materials were characterized by Fourier transform infrared spectroscopy and Brunauer–Emmett–Teller surface area measurements. Among the three deep eutectic solvents, choline chloride/glycerol (1:2) modified magnetic chitosan/carboxymethyl‐β‐cyclodextrin showed the highest adsorption capacity to methyl orange. Therefore, choline chloride/glycerol (1:3, 1:4, 1:5, 1:6) deep eutectic solvents were prepared for the assay, and choline chloride/glycerol‐modified magnetic chitosan/carboxymethyl‐β‐cyclodextrin prepared with choline chloride/glycerol (1:3) (volume: 40 μg, contact time: 30 min, and pH: 6) had the best adsorption capacity over the concentration range of 10–200 μg/mL.     

Suitability of dispersive liquid–liquid microextraction for the in situ silylation of chlorophenols in water samples before gas chromatography with mass spectrometry

Trace analysis of chlorophenols in water was performed by simultaneous silylation and dispersive liquid–liquid microextraction followed by gas chromatography with mass spectrometry. Dispersive liquid–liquid microextraction was carried out using an organic solvent lighter than water (n‐hexane). The effect of different silylating reagents on the method efficiency was investigated. The influence of derivatization reagent volume, presence of catalyst and derivatization/extraction time on the yield of the derivatization reaction was studied. Different parameters affecting extraction efficiency such as kind and volume of extraction and disperser solvents, pH of the sample and addition of salt were also investigated and optimized. Under the optimum conditions, the calibration graphs were linear in the range of 0.05–100 ng/mL and the limit of detection was 0.01 ng/mL. The enrichment factors were 242, 351, and 363 for 4‐chlorophenol, 2,4‐dichlorophenol, and 2,4,6‐trichlorophenol, respectively. The values of intra‐ and inter‐day relative standard deviations were in the range of 3.0–6.4 and 6.1–9.9%, respectively. The applicability of the method was investigated by analyzing water and wastewater samples.     

New Aspects of 1,3‐Diphosphacyclobutane‐2,4‐diyls

1,3‐Di(tert‐butyl)‐2,4‐bis[2,4,6‐tri(tert‐butyl)phenyl]‐1,3‐diphosphacyclobutane‐2,4‐diyl was formed from [2,4,6‐tri(tert‐butyl)phenyl]phosphaacetylene and t‐BuLi. In addition, the X‐ray diffraction analysis was carried out, together with theoretical calculations of the structure and NMR data.     

Rapid analysis of six trace trichlorophenols in seawater by magnetic micro‐solid‐phase extraction and liquid chromatography with tandem mass spectrometry

A new facile, rapid, inexpensive, and sensitive method for the analysis of six trace trichlorophenols in seawater samples was developed by magnetic micro‐solid‐phase extraction coupled to liquid chromatography with tandem mass spectrometry. Core–shell covalently functionalized ferroferric oxide coated with aminated silicon dioxide and decorated with multiwalled carbon nanotubes was applied as an adsorbent to perform the extraction process. The effect of factors including solution pH, contact time, adsorbent amount, and ionic strength were investigated in detail. The obtained results revealed that the proposed adsorbent was a highly effective and low‐cost magnetic micro‐solid‐phase extraction material for the enrichment of 2,3,4‐trichlorophenol, 2,3,5‐trichlorophenol, 2,3,6‐trichlorophenol, 2,4,5‐trichlorophenol, 2,4,6‐trichlorophenol, and 3,4,5‐trichlorophenol from seawater. Under the optimized conditions, the recoveries ranged from 88.0 to 99.5% at the three spiking levels, the limits of detection and the limits of quantification were 0.002 and 0.007 μg/L for the six trichlorophenols, respectively. The intra‐ and interday relative standard deviations were 2.0–6.7 and 4.5–8.9%, respectively. The calibration curves showed a good linearity in the range of 0.02–5.0 μg/L. The routine run analyses showed that the developed method was fast, simple, accurate, solvent‐saving and high resolution, and it was suitable for the determination of trace trichlorophenols in seawater.     

Analysis of short‐chain aliphatic amines in food and water samples using a near infrared cyanine 1‐(ε‐succinimydyl‐hexanoate)‐1′‐methyl‐3,3,3′,3′‐tetramethyl‐indocarbocyanine‐5,5′‐disulfonate potassium with CE–LIF detection

Precolumn derivatization of six short‐chain aliphatic amines by a near‐infrared dye, 1‐(ε‐succinimydyl‐hexanoate)‐1′‐methyl‐3,3,3′,3′‐tetramethyl‐indocarbocyanine‐5,5′‐ disulfonate potassium (MeCy5‐OSu), followed by MEKC–CE–LIF detection has been developed as a method for the determination of aliphatic amines in environmental water and food. Optimum derivatization was operated nicely in pH 9.0 borate buffer at 20°C for 30 min. Well separated peaks were observed with a pH 9.5 BGE containing 10 mmol L^?1 phosphoric acid, 20 mmol L^?1 SDS, and 7% methanol buffered with 1.0 mol L^?1 NaOH. The separation procedure was rapidly achieved within 11 min and the matrix interferences could be effectively eliminated. A linear calibration graph was obtained for 5–200 nmol L^?1 analytes with a correlation coefficient in the range 0.9933–0.9995 for amines. This method was successfully utilized to determine aliphatic amines in lake, sewage water, and red wine with recoveries ranging from 96.4 to 105% and the RSDs ranging from 0.9 to 2.9%. Near‐infrared, LIF‐detector‐compatible MeCy5‐OSu was proved suitable for the accurate, sensitive, and rapid separation and determination of aliphatic amines in water and food samples.