Determination Of Aromatic Amines Research Articles

Determination of nine aromatic amines in water by cloud point extraction-gas chromatography-mass spectrometry

Aromatic amines are a class of compounds bearing amino groups on their benzene rings; these compounds are important raw materials for the industrial production of rubber chemicals, pesticides, dyes, pharmaceuticals, photosensitive chemicals, and agricultural chemicals. Research has revealed that some aromatic amines teratogenetic, carcinogenic, and mutagenic properties. Given the high toxicity and potential harm caused by aromatic amines, monitoring their levels in water sources is critical. Aromatic amines are among the 14 strategic environmental pollutants blacklisted in China, and assessing their exposure levels is essential for protecting human health and the environment. At present, the standard method for detecting aromatic amines in water is liquid-liquid extraction-gas chromatography-mass spectrometry (LLE-GC-MS). However, this method has the disadvantages of large sample size requirement, complex operation, long analysis time, and high reagent consumption. In this study, instead of traditional LLE technology, cloud point extraction (CPE) technology was used in combination with GC-MS to establish an efficient, sensitive, and environment-friendly method for the detection of nine aromatic amines, namely, 2-chloramine, 3-chloramine, 4-chloramine, 2-nitroaniline, 3-nitroaniline, 4-nitroaniline, 1-naphthylamine, 2-naphthylamine, and 4-aminobenzene, in water. Triton X-114 was used as the extraction agent. The main experimental parameters were optimized using a single-factor optimization method. The aromatic amines in various water samples were quantitatively analyzed using GC-MS. The nine aromatic amines were separated on a DB-35 MS capillary column (30 m×0.25 mm×0.25 μm). The mass spectrometer was operated in selected ion monitoring (SIM) mode, and quantitative analysis was performed using the internal standard method. The results demonstrated that all nine aromatic amines could be completely separated within 16 min and had good linearities within accurate mass concentration ranges, with correlation coefficients (R2) greater than 0.998. The limits of detection (LODs) and quantification (LOQs) of these aromatic amines in water were 0.12-0.48 and 0.40-1.60 μg/L, respectively. The accuracy and precision of the method were assessed via the determination of aromatic amines in surface water of drinking water sources, offshore seawater, wastewater of the typical printing and dyeing industry at levels of 2.0 and 10.0 μg/L. The recoveries of the aromatic amines in surface water of drinking water sources were 81.1%-109.8%, with intra-day and inter-day relative standard deviations (RSDs) of 0.7%-5.2% (n=6) and 1.6%-6.2% (n=3), respectively. The recoveries of the aromatic amines in offshore seawater were 83.0%-115.8%, with intra-day RSDs (n=6) of 1.5%-8.6% and inter-day RSDs (n=3) of 2.4%-12.2%. The recoveries of the nine aromatic amines in wastewater of the typical printing and dyeing industry were 91.0%-120.0%, with intra-day RSDs (n=6) of 2.9%-12.9% and inter-day RSDs (n=3) of 2.5%-13.1%. The established method was used to detect nine aromatic amines in actual water samples. No aromatic amines were detected in the surface water of drinking water sources or offshore seawater samples. However, 2-chloramine, 4-chloramine, and 4-aminobenzene, which are frequently used in the printing and dyeing industry, were detected in the wastewater of the typical printing and dyeing industry samples. The proposed method offers the advantages of simple operation, high sensitivity, low cost, low organic reagent requirement, and good repeatability. Thus, this method provides reliable technical support for studying the residual status and environmental behavior of aromatic amines in water.

External quality assurance schemes (EQUASs) and interlaboratory comparison investigations (ICIs) for the human biomonitoring of aromatic amines in urine as part of the quality assurance programme under HBM4EU.

Exposure to aromatic amines may occur via tobacco smoke, hair dyes or tattoo inks, but also in the workplace during certain manufacturing processes. As some aromatic amines are known or suspected carcinogens, human biomonitoring (HBM) is essential to assess their exposure. Aromatic amines were among the selected chemicals in HBM4EU, a European-wide project to harmonise and advance HBM within 30 European countries. For this purpose, the analytical comparability and accuracy of participating laboratories were assessed by a QA/QC programme comprising interlaboratory comparison investigations (ICIs) and external quality assurance schemes (EQUASs). This paper presents the evaluation process and discusses the results of three ICI/EQUAS rounds for the determination of aromatic amines in urine conducted in 2019 and 2020. The final evaluation included ten participants which analysed the following six targeted aromatic amines over three rounds: aniline, ortho-toluidine (TOL), 4,4'-methylenedianiline (MDA), 4,4'-methylenebis(2-chloroaniline) (MOCA), 2,4-diaminotoluene (2,4-TDA), and 2,6-diaminotoluene (2,6-TDA). Most participants achieved satisfactory and highly comparable results, although low quantification limits were required to quantify the parameters at the level of exposure in the general population. Hydrolysis of the sample followed by liquid-liquid extraction and subsequent analysis of the derivatised analytes by means of GC-MS/MS were preferred for the sensitive and precise determination of aromatic amines in urine. This QA/QC programme succeeded in establishing a network of laboratories with high analytical comparability and accuracy for the analysis of aromatic amines in Europe.

Highly sensitive AuNSs@AgNR SERS substrates for rapid determination of aromatic amines.

The leakage of aromatic amines will pose a great threat to human health and the ecological environment. Therefore, there is an urgent need to achieve rapid and high-sensitivity detection of such substances. In this study, a simple surface-enhanced Raman scattering (SERS) method based on gold nanostars-modified silver nanorods (AuNSs@AgNRs) was established for the detection of benzidine and 4-aminobiphenyl (4-ABP). The enhancement factors of the substrate towards rhodamine 6G (R6G) and crystal violet (CV) were 4.67 × 108 and 1.11 × 108, respectively. Combined with density functional theory (DFT), the AuNSs@AgNR substrate achieved the rapid detection of benzidine and 4-ABP and obtained low detection limits (LODbenzidine = 7.09 × 10-9 M; LOD4-ABP = 1.20 × 10-9 M). Furthermore, the AuNSs@AgNR substrate can realize the high-sensitivity detection of benzidine and 4-ABP in the spiked river water samples within 3 min, which means that the AuNSs@AgNR-based SERS method can be used as a portable platform to realize the on-site rapid detection of environmental pollutants.

Determination of aromatic amines in environmental water samples by deep eutectic solvent-based dispersive liquid-liquid microextraction followed by HPLC-UV

This study reports a deep eutectic solvent based dispersive liquid-liquid microextraction (DES-DLLME) to extract aromatic amines (4-chloroaniline, 3-nitroaniline, 2-naphtylamine) in environmental water samples before their HPLC-UV determination. The hydrophobic deep eutectic solvent (DES) was prepared by mixing bis(2-ethylhexyl) phosphate (BEHP) as a hydrogen bond acceptor and phenol as a hydrogen bond donor. Affecting factors on the extraction of the aromatic amines were investigated and optimized. Optimum conditions were: DES type: BHHP-Ph ratio: 1 to 2; pH of solution: 8.0; DES volume: 80 µL, salt amount: 10% (w/v). Under optimum conditions, the developed method showed a wide linear range of 0.2–200 µg L−1 (R2 ≥ 0.99) with satisfactory recoveries (≥90.0%). The limit of detections (LODs) and limit of quantifications (LOQs) were in the range of 0.07–0.17 µg L−1 and 0.2–0.5 µg L−1, respectively. The enrichment factors were 170, 180 and 190 for 4-chloroaninile, 3-nitroaniline, 2-naphtylamine, respectively. Based on obtained results, the proposed method is straightforward, efficient, sensitive, and eco-friendly for the extracting and determining of the aromatic amines in environmental water samples.

Application of vortex assisted dispersive liquid-liquid microextraction based on a new deep eutectic solvent for microextraction of aromatic amines from simulant of kitchenware samples by HPLC-UV

This paper reports a dispersive liquid–liquid microextraction based on a novel hydrophobic deep eutectic solvent (HDES) for the extraction of aromatic amines (aniline, 4-methoxyanniline, 4,4′-diaminodiphenyl, orthotoluidine, 2,6-dimethylaniline, 2-naphtylamine) in simulant of colored kitchenware samples before their high-performance liquid chromatography determination. The HDES was prepared by mixing bis(2-ethylhexyl) phosphoric acid (BEHPA) as hydrogen bond acceptor and thymol as hydrogen bond donor. Affecting factors on the extraction of the aromatic amines were investigated and optimized. Under optimum conditions, the developed method showed a wide linear range of 1.0–200 µg L−1 (R2 ≥ 0.99) with satisfactory recoveries (≥90.0%). The empirical limit of detections (LODs) were in the range of 1.5–3.0 µg L−1. The method LOQ was 5.0 µg L−1. The enrichment factors were in the range of 170–190. The intra-day (n = 6) and inter-day (n = 3) precisions at concentration levels of 5, 50 and 200 µg L−1 were ≤ 8.1%. Based on obtained results, the proposed method is very simple, efficient, sensitive, and eco-friendly for the extraction and determination of aromatic amines in simulant of colored kitchenware samples.

Development of a green and efficient methodology for the heterocyclic aromatic amine determination in biomass samples generated from cigarette combustion and tobacco.

A green methodology was developed for the analysis of ten heterocyclic aromatic amines (HAAs) in biomass samples from cigarette combustion such as mainstream smoke, paper ashes, as well as tobacco and paper wraps. The cellulose filter used for sample collection was also evaluated. This strategy was based on ultrasound-assisted extraction (UAE) associated with a solid-phase extraction procedure employing multi-walled carbon nanotubes (MWCNTs-SPE) as a cleanup step followed by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Under optimal experimental conditions, the linearity of the method was in the range from 0.08 to 160 ng cig-1, with correlation coefficients (R2) higher than 0.991. The limits of detection resulted to be between 0.03 and 0.63 ng cig-1. Concentrations of the HAAs in the mainstream smoke were from 5.7 to 145.2 ng cig-1 and in paper ashes from 0.1 to 0.6 ng cig -1, while in tobacco were between 1.0 and 38.5 ng cig-1. Meanwhile, no HAA contribution was observed in the case of paper wraps and the filter used for sample collection. The knowledge of the presence and the concentration levels of the selected HAAs in each cigarette's physical component after its combustion is essential to understand the formation processes and contribution during cigarette burning. Besides, this is the first report about the presence of some HAAs in the proposed samples. Finally, a comparative study was employed to classify the sustainability of several recent approaches for HAA extraction from cigarette combustion samples using Green Certificate as a metric tool.

Liquid Chromatographic Determination of Aromatic Amines in Water Samples after Gold Nanoparticles Coated Membrane Microextraction

A novel microextraction technique was developed for aromatic amines using gold nanoparticles coated membrane. The preparation of the extraction device involves with the synthesis of gold nanoparticles via the reduction of AuCl3 by hydroxyethyl cellulose followed by coating to the polyethersulfone membrane. The simple extraction procedures involved placing the extraction device in a stirred aqueous sample solution, followed by desorption in an organic solvent using ultrasonication. The extract was analyzed by high performance liquid chromatography. Optimal extraction conditions include 50 min extraction time, 20 min desorption time, 30 mL sample volume, sample pH 10, 5 % NaCl content and 17 mg sorbent mass coupled with 100 μL desorption solvent. The performance of the extraction device in the absence and presence of gold nanoparticles was investigated. Enrichment factors ranged from 148 (for 3-nitroaniline) to 200 (for 3,4- dichloroaniline). The calibration results exhibited good linearity (r2 = 0.9931-0.9988) within the range 0.5-20 μg/L. The limits of detection were 0.3-0.7 μg/L and RSDs (n = 6) 10-19%. Comparison was made with solid-phase extraction. The method was subsequently applied to municipal wastewater samples. The proposed microextraction method offers advantages such as easy operation, high recovery, faster extraction, minimal use of organic solvent and elimination of tedious solvent evaporation and reconstitution steps.

Novel deep eutectic solvent-based ultrasounds-assisted dispersive liquid-liquid microextraction with solidification of the aqueous phase for HPLC-UV determination of aromatic amines in environmental samples.

In this study, a green and efficient sample preparation method using a deep eutectic solvent-based ultrasounds-assisted dispersive liquid–liquid microextraction with solidification of the aqueous phase (DES-UA-DLLME-SAP) followed by HPLC-UV was developed for preconcentration and determination of aromatic amines in aqueous environmental samples. In the proposed method, a novel deep eutectic solvent (DES) characterized by low density was prepared by mixing trihexyl(tetradecyl)phosphonium chloride and decanol at a molar ratio of 1:2. Ultrasounds were used to disperse the extractant in the aqueous phase of the sample. Then, the phases were separated by centrifugation, after which the aqueous phase was frozen and the surface DES phase was dissolved in a small volume of methanol before injection into the chromatograph. Various factors, including the selection of extractant and its volume, pH of the sample, duration of ultrasounds treatment, the time and rate of centrifugation and salt addition, were investigated and optimized. Under optimal conditions (40 µL of DES, pH = 12, 60 s of ultrasound use, 10 min/4500 rpm of centrifugation, 40 mg of NaCl), the proposed method allowed to achieve good precision (n = 6) between 2.9 and 6.2% at 0.4, 5.0 and 40.0 ng mL−1 levels, respectively. The preconcentration factors were equal to 119, 116 and 121 for 2-chloroaniline, 4-chloroaniline and 1-naphthylamine, respectively. The limits of detection were equal to 0.07 ng mL−1 for 2-chloroaniline, 0.11 ng mL−1 for 4-chloroaniline and 0.08 ng mL−1 for 1-naphthylamine. The proposed method was successfully applied for determination of aromatic amines in aqueous environmental samples with a good recoveries in the range of 85.1–99.9%

Determination of aromatic amines in wastewater by capillary electrophoresis

The possibility of aromatic amine determination using capillary electrophoresis on a «KAPEL-105M» device is studied. Due to their high toxicity, aromatic amines are rated as top- priority environmental pollutants and their content in the atmosphere and water in no way should not exceed MAC. Therefore, improvement and optimization of the instrumental methods of their determination, which can shorten the sample preparation, reduce analysis time, increase accuracy of determination, and also enable automation of analysis becomes an urgent goal of the study. A method for the separation and determination of aromatic amines (aniline, benzidine, 2-aminophenol, 1- and 2-naphthylamines, 2,6-diaminopyridine) by capillary electrophoresis on a «KAPEL-105M» device with a UV detector was developed. We have specified optimal conditions for the determination of aromatic amines (wavelength, pressure, time of sample introduction, voltage) and selected the most suitable electrolyte. The effect of the nature and concentration of the electrolyte on the determination of amines was analized. The developed method exhibited good reproducibility, accuracy, selectivity of determination, and the absence of the interfering influence of the basis of the wastewater sample. The developed method for determination of the aromatic amines was tested on model solutions and real samples of waste water, whereas the correctness of the procedure was proved in spike tests. Direct spectrophotometric detection (λ = 215 nm) revealed the following detection limits: 0.1 mg/dm3 for 1- and 2-naphthylamines, 0.5 mg/dm3 for aniline, 2-aminophenol and benzidine, and 1.0 mg/dm3 — for 2,6-diaminopyridine.

Three-color luminescent transformation of the julolidine pyrylo/pyridocyanine dyes in the adsorbed state

Pyrylocyanine dyes with julolidinyl donor groups are used for determination of aromatic amines on silica gel. The formed julolidine pyridocyanines are unstable on silica support and give bright three-color luminescent products: initial red proceeds to green and blue. The latter appear due to oxidation and dehydration of the julolidine cycle in the pyridocyanine dye formed. The structures of pyridocyanine oxidized forms were established by X-ray and NMR methods. The luminescence spectra transformations of the pyridocyanines on silica support and the evidence of the chemical and photochemical oxidation by the air oxygen are represented.

Synthesis of sulfonated crosslinked polystyrene applied to the determination of aromatic amines derived from azo dyes in textile

Sulfonated microphere material based on crosslinked polystyrene was synthesized by emulsification polymerization, the polymerization yield was of 75 % ± 5 % and the size of microspheres was ranging from 30–180 µm. In order to obtain the suitable capacity for the enrichment of aromatic amines (1.0 meqv/g) the condition for sulfonation process were derived from the model based on an experimental design. The products were used as a stationary phase in solid phase extraction (SPE) to enrich 18 aromatic amines derived from banned azo dyes in textile. In this study, an analytical method has been developed, with LOQ of 2 ppm. The correlation coefficient R2 of the cabliration curve was ≥ 0.9997, most of the aromatic amines had the recoveries > 80 % and RSD < 5 %. In addition, a comparison between obtained results by the developed method and those by international standard methods BS EN 14326-1: 2012 and BS EN 14326-3:2012, was also done.

Determination of aromatic amines in the urine of smokers using a porous organic framework (JUC-Z2)-coated solid-phase microextraction fiber

A solid-phase microextraction (SPME) fiber coated with a two-dimensional porous organic framework (POF), JUC-Z2, was synthesized by a sol-gel process. The JUC-Z2-coated SPME fiber was combined with gas chromatography-mass spectrometry/mass spectrometry (GC–MS/MS), and a direct analysis method without any derivatization step was developed for the determination of two major harmful aromatic amines (1-naphthylamine, 1-NA; 2-naphthylamine, 2-NA) in the urine of amokers. The new method exhibited satisfactory linearity in the wide range of 0.05–100 μg L−1 with correlation coefficients (R) of 0.9999. The limits of detection are 0.010 and 0.012 ng L−1. The relative standard deviations for repeated extraction (n = 6) with one fiber are less than 7.7%. The JUC-Z2-coated fiber demonstrates obviously superior extraction efficiencies for the two aromatic amines over the commercial fibers (CW/PEG, PA, PDMS/DVB, PDMS, CAR/PDMS, DVB/CAR PDMS). The structure-activity relationship was deeply investigated by the extraction comparison experiment with another similar POF material (PAF-48) and theoretical simulations. The extraction efficiencies of JUC-Z2 for 1-NA and 2-NA are 9.6 and 16.2 times higher than those of PAF-48, and JUC-Z2 has higher binding energies with the aromatic amines than PAF-48. The results indicate that the N atom on the JUZ-Z2 framework played a crucial role for adsorbing aromatic amines. Finally, the novel fiber has been successfully used to detect 1-NA and 2-NA in the urine of smokers.

A nanocomposite consisting of poly(methyl methacrylate), graphene oxide and Fe3O4 nanoparticles as a sorbent for magnetic solid-phase extraction of aromatic amines.

Graphene oxide (GO) was conjugated to magnetite nanoparticles and then coated with poly(methyl methacrylate) to obtain a nanomaterial of the type PMMA@GO-Fe3O4, which is shown to be a viable sorbent for magnetic solid-phase extraction. The nanocomposite was characterized by SEM, TEM, XRD, VSM and FTIR spectroscopy. It was applied to the extraction of the aromatic amines aniline, N,N-dimethylaniline, o-toluidine, and 3-chloroaniline. Under optimal conditions, the preconcentration factors range from 139 to 173. Following desorption with dichloromethane, the amines were quantified by GC. Analytical figures of merit include (a) a linear range extending from 0.007-100ng mL-1, (b) detection limits between 2 and 6pg mL-1; and (c) relative standard deviations between 5.9 and 8.6% (for n = 5; at 0.05, 5.0 and 50ng mL-1 levels, respectively). The method was successfully applied to the determination of aromatic amines in spiked real water samples and gave recoveries in the range of 90.3%-99.0%. Graphical abstract A magnetic sorbent was fabricated by deposition of poly(methyl methacrylate) onto Fe3O4-magnetized graphene oxide. It was applied to the extraction and preconcentration of aromatic amines from water samples prior to their gas chromatography-flame ionization detector (GC-FID) determination.

Analysis of six aromatic amines stability in workplace measurement

For aromatic amine determination in workplaces, stabilities of six types of carcinogenic aromatic amines (2,4-diaminotoluene, 4,4'-diamino-3,3'-dimethyldiphenylmethane, o-tolidine, 3,3'-dichlorobenzidine, 4,4'-methylenebis(2-chloroaniline), and o-dianisidine) were evaluated with air or argon gas bubbling for 45 min in aqueous solution under light irradiation (desk lamp) and heating conditions. Gas chromatography–mass spectrometry (GC–MS) was used to identify and quantify the aromatic amines. The following conditions were selected: temperature program 70°C (1 min), 7 grad/min up to 120°C (1 min), 10 grad/min up to 300°C (5 min), carrier gas flow rate 1.0 mL/min. 3,3'-Dichlorobenzidine concentration decreased by approximately 10% after irradiation with a desk lamp for 45 min in distilled water, and a monochloro compound was detected by GC–MS. The other aromatic amines were rarely different from the 0-min concentration. The shielding prevented the decomposition of 3,3'-dichlorobenzidine in distilled water.

Determination of Aromatic Amines Released from Azo Dyes in Paper Packaging by Liquid Chromatography-Tandem Mass Spectrometry

An LC-tandem MS (LC-MS/MS) method for the determination of 21 kinds of carcinogenic aromatic amines released from azo dyes in food wrappers was used in this research. Sodium dithionite was added to a citric acid buffer medium to reduce and decompose possible azo dyes. The extract was analyzed after liquid-liquid extraction (LLE) and dispersive SPE (d-SPE). The conditions for chromatographic separation, mass spectrum, LLE, and d-SPE were optimized. Under optimal conditions, the LOD was in the range of 0.13-0.35 mg/kg and LOQ in the range of 0.38-1.05 mg/kg, with the addition of standard recoveries of most aromatic amines being ≥80% and RSDs ≤10%. The recoveries for 2,4-diaminotoluene and 2,4-diaminoanisole were significantly lower, being ≤40%. The method was successfully used to analyze 30 practical samples, and the results showed that it is user-friendly, with high sensitivity, rapid control, and low matrix interference.

Determination of aromatic amines in environmental water samples using solid-phase extraction modified with sodium dodecyl sulphate and micellar liquid chromatography

ABSTRACTExtraction and determination of seven aromatic amines in environmental water samples were performed with solid-phase extraction (SPE) and micellar liquid chromatography (MLC) using experimental design. Extraction of aromatic amines was carried out with a C18 cartridge modified with sodium dodecyl sulphate (SDS). The washing solution and elution solvent for extraction of aromatic amines were aqueous solution containing 5% (v/v) acetonitrile and 5% (v/v) acetone and 3 mL methanol, respectively. The chemometrics approach was applied for the separation optimisation of these compounds using MLC. Different mobile phase compositions were used for modelling based on retention times to obtain the best separation using central composite design. The optimum mobile phase composition for separation and determination of analytes in water samples was 69 mM SDS, 9% v/v 1-propanol and pH = 6.4. Recoveries were between 84.8–93.5% with relative standard deviation (RSD) less than 5.8% (n = 5). Limits of detection and linear range were 1–4.5 and 3.1–125.0 µg/L, respectively. The proposed method was applied to determine the aromatic amines in real samples (river and well waters). Amount of 4-nitroaniline and 3-nitroaniline in river water sample were 2.15 and 1.91 µg/L, respectively.

Determination of Aromatic Amines Using Solid-Phase Microextraction Based on an Ionic Liquid-Mediated Sol-Gel Technique.

A headspace solid-phase microextraction (HS-SPME) method was developed for isolation of monocyclic aromatic amines from water samples followed by gas chromatography-flame ionization detector (GC-FID). In this work, the effect of the presence of ionic liquid (namely, 1-hexyl-3-methyl-imidazolium hexafluorophosphate [C6MIM][PF6]) was investigated in the sol-gel coating solutions on the morphology and extraction behavior of the resulting hybrid organic-inorganic sol-gel sorbents utilized in SPME. Hydroxy-terminated poly(dimethylsiloxane) (PDMS) was used as the sol-gel active organic component for sol-gel hybrid coatings. Two different coated fibers that were prepared are PDMS and PDMS-IL ([C6MIM][PF6]) fibers. Under the optimal conditions, the method detection limits (S/N = 3) with PDMS-IL were in the range of 0.001-0.1 ng/mL and the limits of quantification (S/N = 10) between 0.005 and 0.5 ng/mL. The relative standard deviations for one fiber (n = 5) were obtained from 3.1 up to 8.5% and between fibers or batch to batch (n = 3) in the range of 5.3-10.1%. The developed method was successfully applied to real water and juice fruits samples while the relative recovery percentages obtained for the spiked water samples at 0.1 ng/mL were from 83.3 to 95.0%.

Application of an Ultrasound-assisted Polymer Surfactant-enhanced Emulsification Microextraction for Determination of Aromatic Amines in Water Sample

A simple and efficient method, based on ultrasound-assisted polymer surfactant-enhanced emulsification microextraction (SA-USAEME) followed by gas chromatography-mass spectrometry (GC-MS), has been developed for the determination of eight aromatic amines (AAs) in aqueous sample. The main parameters affecting the performance of the proposed method were optimized, and the optimum conditions were obtained as follows: 150 μL of extractive solvent (dichloroethane) 150 μL, polymer surfactant (sodium alginate) of 0.20 g L−1, pH 7.0, salt addition of 3%, and ultrasound time of 1 min. Under the optimal conditions, the linear ranges were 0.1-200 μg L−1 for 3,3′-dichlorobenzidine, 0.3-200 μg L−1 for 2,4,5-trime concentration thylaniline, 4-chloro-o-toluidine, 3,3′-dimethyl-4,4′-diaminodiphenylmethane, 3,3′-dimethylbenzidine and 4,4′-methylene-bis-(2-chloroaniline), and 0.5-200 μg L−1 for 4-aminoazobenzene and 3,3′-dimethoxybenzidine. The correlation coefficients (R2) and detection limits were 0.9961-0.9997 and 0.08-0.3 μg L−1 respectively. The intra- and inter-RSD were less than 10.3% and 11.9%. Additionally, the proposed method could be applied to the analysis of AAs in water sample respectively collected from tap water and river water. Compared with the common SA-USAEME, conventional surfactant was replaced with water-soluble polymer surfactant in this method to solve the problems of potential pollution and decrease the GC limitation since the polymer surfactant were natural and insoluble in extractive solvent. Compared with solid phase extraction, the proposed method enjoyed simplicity of operation and low cost. Therefore, it is an alternative method that could be widely used for the analysis of trace level of AAs in water sample.

Fiber-assisted emulsification microextraction coupled with gas chromatography–mass spectrometry for the determination of aromatic amines in aqueous samples

A novel fiber-assisted emulsification microextraction (FAEME) method was developed for the determination of eight aromatic amines (AAs) in aqueous samples. In this method, the extraction solvent (100μL chlorobenzene) and the dispersive material (1.0mg kapok fiber fragments) were added successively into the aqueous sample (5.0mL), and then the mixture was emulsified by ultrasound to form the cloudy solution. Phase separation was performed by centrifugation, and the sedimented phase was transferred to micro-inserts with a microsyringe for analysis. All variables involved in the extraction process were identified and optimized. By coupling the analysis with gas chromatography–mass spectrometry (GC–MS), excellent detection limits (0.01–0.2μgL−1), good precision (RSDs, 3.33–6.56%) and linear ranges (0.10–160μgL−1 and 1.0–160μgL−1) were obtained. Compared with the traditional solvent-emulsification method, the extraction recoveries of the proposed method were much higher. Satisfactory recoveries were achieved when the method was used for the analysis of AAs in spiked real water samples.

A simple, rapid and eco-friendly approach for the analysis of aromatic amines in environmental water using single-drop microextraction-gas chromatography.

Single-drop microextraction (SDME) coupled with gas chromatography-flame ionization detector (GC-FID) was developed for the extraction and determination of aromatic amines (AAs) in environmental water samples. A silicon tube was introduced for the SDME procedure by inserting it into the needle of the micro-injector. In this manner, a large volume of extractant is allowed to be suspended for the extraction, leading to the enhancement of method sensitivity and reproducibility. Extraction parameters which control the performance of SDME such as the type of microextraction solvent and volume, sample pH, ionic strength and extraction time were investigated and optimized. Under the optimized conditions, the SDME-GC method exhibited good linearity from 0.5 to 50 μg mL(-1) for aniline and 4-methylaniline and 0.1 to 50 μg mL(-1) for N-methylaniline and N, N-diethylaniline. The enrichment factors were calculated to be 42-509. The SDME-GC method was performed for the determination of AAs in environmental water samples including drinking, lake and sea water, and excellent recoveries and relative standard deviations (RSD values) ranging from 79.5 to 122.7% and 3.2 to 13.3%, respectively, were obtained. The results demonstrated that SDME-GC is a rapid, simple and effective sample preparation method and could be successfully applied for the determination of AAs in environmental water samples.