In situ ionic‐liquid‐dispersive liquid–liquid microextraction of Sudan dyes from liquid samples

In situ ionic‐liquid‐dispersive liquid–liquid microextraction was introduced for extracting Sudan dyes from different liquid samples followed by detection using ultrafast liquid chromatography. The extraction and metathesis reaction can be performed simultaneously, the extraction time was shortened notably and higher enrichment factors can be obtained compared with traditional dispersive liquid–liquid microextraction. When the extraction was coupled with ultrafast liquid chromatography, a green, convenient, cheap, and efficient method for the determination of Sudan dyes was developed. The effects of various experimental factors, including type of extraction solvent, amount of 1‐hexyl‐3‐methylimidazolium chloride, ratio of ammonium hexafluorophosphate to 1‐hexyl‐3‐methylimidazolium chloride, pH value, salt concentration in sample solution, extraction time and centrifugation time were investigated and optimized for the extraction of four kinds of Sudan dyes. The limits of detection for Sudan I, II, III, and IV were 0.324, 0.299, 0.390, and 0.655 ng/mL, respectively. Recoveries obtained by analyzing the seven spiked samples were between 65.95 and 112.82%. The consumption of organic solvent (120 μL acetonitrile per sample) was very low, so it could be considered as a green analytical method.     

Determination of aromatic amines from azo dyes reduction by liquid‐phase sorbent trapping and thermal desorption‐gas chromatography‐mass spectrometry

A novel method based on thermal desorption was developed for the trapping of aromatic amines from azo dyes reduction in liquid phase. Combining GC‐MS, the detection limits for 21 kinds of aromatic amines ranged from 0.1 to 3 mg/kg. The recoveries of most aromatic amines were ?70% with RSDs ?10%. This method also offers low sample and organic solvent requirements, effective preconcentration and convenient procedure. It has been applied to determine aromatic amines from the real samples of textile and yielded good results.     

New approach applying a pet fish air pump in liquid‐phase microextraction for the determination of Sudan dyes in food samples by HPLC

A new approach applying a pet fish air pump is introduced to develop an extraction method, namely, air‐pump‐enhanced emulsion, followed by salt‐assisted emulsion breaking based on solidified floating organic drop microextraction for the extraction and preconcentration of Sudan I–IV before high‐performance liquid chromatography. The applicability of this method was successfully demonstrated by determination of these dyes in four chili products that include chili powder, chili oil, chili sauce, and chili paste. An enrichment factor of 62 was obtained only with a sample solution of 5 mL. A linear range of 0.5–2500 ng/mL was obtained with a limit of detection of 0.16–0.24 ng/mL and recovery of 90–110%. This method is superior to other liquid–liquid extraction methods, as is simple, rapid, environmental friendly, and its phase separation needs no centrifugation. It also needs no disperser solvent and requires less organic solvent, and satisfies the criteria to be called as a green extraction. Therefore, this facile extraction method can be successfully applied in the determination of Sudan dyes in food samples.     

Electromembrane extraction of gonadotropin‐releasing hormone agonists from plasma and wastewater samples

In the present study, for the first time electromembrane extraction followed by high performance liquid chromatography coupled with ultraviolet detection was optimized and validated for quantification of four gonadotropin‐releasing hormone agonist anticancer peptides (alarelin, leuprolide, buserelin and triptorelin) in biological and aqueous samples. The parameters influencing electromigration were investigated and optimized. The membrane consists 95% of 1‐octanol and 5% di‐(2‐ethylhexyl)‐phosphate immobilized in the pores of a hollow fiber. A 20 V electrical field was applied to make the analytes migrate from sample solution with pH 7.0, through the supported liquid membrane into an acidic acceptor solution with pH 1.0 which was located inside the lumen of hollow fiber. Extraction recoveries in the range of 49 and 71% within 15 min extraction time were obtained in different biological matrices which resulted in preconcentration factors in the range of 82–118 and satisfactory repeatability (7.1 < RSD% < 19.8). The method offers good linearity (2.0–1000 ng/mL) with estimation of regression coefficient higher than 0.998. The procedure allows very low detection and quantitation limits of 0.2 and 0.6 ng/mL, respectively. Finally, it was applied to determination and quantification of peptides in human plasma and wastewater samples and satisfactory results were yielded.     

Subcritical water and dynamic sonication-assisted solvent extraction of fluorescent whitening agents and azo dyes in paper samples

Two low-volume solvent continuous extraction methods are applied to the extraction of paper matrices. In the methods reported here, a complex mixture of fluorescent whitening agents (FWAs) and azo dyes (AZOs) used in paper materials intended to come into contact with foodstuffs was extracted by using subcritical water extraction (SWE) and dynamic sonication-assisted solvent extraction (DSASE). Rationale for the work is based upon migration concerns of these groups of analytes from the packaging to the packaged items, thus compromising their subjective and/or objective quality. In SWE, sample was extracted in 21 min with 0.5 mL of water, whereas the DSASE method required 11 min and used 7 mL of water. DSASE was further developed by incorporating an organic modifier in order to change water polarity, thus improving extraction of moderately polar analytes. This way, modified-DSASE used a total organic volume of 0.9 mL which represents a reduction of 200 times in organic solvent consumption (200 mL versus approximately 1.0 mL) and 11 times in extraction time (2h versus 11 min) compared to the existing methods. SWE was able to extract only 9 out of 12 test analytes with average recoveries between 10 and 25% whereas modified-DSASE succeed in extracting all the target analytes with an average recovery of 89%. Complete discussion and explanation concerning these differences are provided in the text.     

Polysaccharide/Fe(III)-porphyrin hybrid film as catalyst for oxidative decolorization of toxic azo dyes: An approach for wastewater treatment

A hybrid film of chitosan/poly(vinyl alcohol)/cationic Fe(III)-porphyrin (Cht/PVA-FeTMPyP) was synthesized to act as a Fenton-like catalyst to decolorize methyl orange and methyl red azo dyes. The Cht/PVA-FeTMPyP film was characterized by different analytical and microscopy techniques, which indicated that the metalloporphyrin affects different properties of the hybrid film. Batch experiments revealed that the hybrid film exhibits enhanced catalytic activity towards dyes decolorization in the presence of H₂O₂ as compared to the “free” FeTMPyP. Fast decolorization rates as high as 90 min were observed for both azo dyes under mild conditions (pH 7 and room temperature), even at low concentrations of the catalyst in H₂O₂. After the decolorization, FTIR analysis showed that simple molecules are released as by-products. Moreover, the hybrid film performed well in cyclic runs without leaching out iron ions or losing its catalytic activity. All these features associated with its ease handling ranks the Cht/PVA-FeTMPyP hybrid film as a promising heterogeneous Fenton-like catalyst for the decomposition of azo dyes in water.     

Fabrication of highly crystalline covalent organic framework for solid-phase extraction of three dyes from food and water samples

Herein, a covalent organic framework, which was fabricated at room temperature by using 1,3,5-tris(p-formylphenyl) benzene and 1,3,5-tris(4-aminophenyl)benzene as building blocks, was employed as an adsorbent for solid-phase extraction of dyes including congo red, methyl blue and direct red 80 for the first time. The prepared covalent organic framework was properly characterized by different techniques and the results revealed that it had a uniform spherical structure, high crystallinity, satisfactory surface area, and good thermal stability. Moreover, the adsorption performance of the material was explored by using static and dynamic adsorption experiments and the results indicated that the material showed good adsorption capacities for three dyes with adsorption capacities in the range of 55.25–284.10 mg/g and the adsorption equilibrium can be achieved in 15 min. Further, to achieve the best adsorption effects of the material, the influence parameters such as pH, ionic strength, type of desorption solvent, and the material dosage in the solid-phase extraction column, were optimized in turn. Finally, under optimal conditions, the solid-phase extraction coupled with HPLC was applied to the analysis of dyes in food and water samples. The recoveries of dyes in actual samples were satisfactory, revealing the unique applicability of the material in the sample pretreatment field.     

Capillary electrophoresis determination of nonsteroidal anti‐inflammatory drugs in wastewater using hollow fiber liquid‐phase microextraction

The presence of pharmaceuticals in the environment due to growing worldwide consumption has become an important problem that requires analytical solutions. This paper describes a CE determination for several nonsteroidal anti‐inflammatory drugs (ibuprofen, naproxen, ketoprofen, diclofenac, ketorolac, aceclofenac and salicylic acid) in environmental waters using hollow fiber membrane liquid‐phase microextraction. The extraction was carried out using a polypropylene membrane supporting dihexyl ether and the electrophoretic separation was performed in acetate buffer (30 mM, pH 4) using ACN as the organic modifier. Detection limits between 0.25 and 0.86 ng/mL were obtained, respectively. The method could be applied to the direct determination of the seven anti‐inflammatories in wastewaters, and five of them have been determined or detected in different urban wastewaters.     

Selective recognition and discrimination of water‐soluble azo dyes by a seven‐channel molecularly imprinted polymer sensor array

A seven‐channel molecularly imprinted polymer sensor array was prepared and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, UV‐Vis spectroscopy, and nitrogen physisorption studies. The results revealed that the imprinted polymers have distinct‐binding affinities from those of structurally similar azo dyes. Analysis of the UV‐Vis spectral response patterns of the seven dye analytes against the imprinted polymer array suggested that the different selectivity patterns of the array were closely connected to the imprinting process. To evaluate the effectiveness of the array format, the binding of a series of analytes was individually measured for each of the seven polymers, made with different templates (including one control polymer synthesized without the use of a template). The response patterns of the array to the selected azo dyes were processed by canonical discriminant analysis. The results showed that the molecularly imprinted array was able to discriminate each analyte with 100% accuracy. Moreover, the azo dyes in two real samples, spiked chrysoidin in smoked bean curd extract and Fanta lime soda (containing tartrazine), were successfully classified by the array.     

Two‐phase and three‐phase liquid‐phase microextraction of hydrochlorothiazide and triamterene in urine samples

This paper reports the applicability of two‐phase and three‐phase hollow fiber based liquid‐phase microextraction (HF‐LPME) for the extraction of hydrochlorothiazide (HYD) and triamterene (TRM) from human urine. The HYD in two‐phase HF‐LPME is extracted from 24 mL of the aqueous sample into an organic phase with microliter volume located inside the pores and lumen of a polypropylene hollow fiber as acceptor phase, but the TRM in three‐phase HF‐LPME is extracted from aqueous donor phase to organic phase and then back‐extracted to the aqueous acceptor phase, which can be directly injected into HPLC for analysis. Under optimized conditions preconcentration factors of HYD and TRM were obtained as 128 and 239, respectively. The calibration curves were linear (R² ≥ 0.995) in the concentration range of 1.0–100 µg/L for HYD and 2.0–100 µg/L for TRM. The limits of detection for HYD and TRM were 0.5 µg/L. The intra‐day and inter‐day RSD based on four replicates were obtained as ≤5.8 and ≤9.3%, respectively. The methods were successfully applied for determining the concentration of the drugs in urine samples. Copyright © 2015 John Wiley & Sons, Ltd.     

Determination of four acidic nonsteroidal anti‐inflammatory drugs in wastewater samples by dispersive liquid–liquid microextraction based on solidification of floating organic droplet and high‐performance liquid chromatography

A simple, environmentally friendly, and sensitive dispersive liquid–liquid microextraction based on solidification of floating organic droplet for the extraction of four acidic nonsteroidal anti‐inflammatory drugs (ketoprofen, naproxen, ibuprofen, and diclofenac) from wastewater samples subsequent by high‐performance liquid chromatography analysis was developed. The influence of extraction parameters such as pH, the effect of solution ionic strength, type of extraction solvent, disperser solvent, and extraction solvent volume were studied. High enrichment factors (283–302) were obtained through the developed method. The method provides good linearity (r > 0.999) in a concentration range of 1–100 μg/L, good intra‐ and inter‐day precision (relative standard deviation < 7%) and low limits of quantification. The relative recoveries of the selected compounds were situated over 80% both in synthetic and real water samples. The developed method has been successfully applied for the analysis of the selected compounds in wastewater samples.     

Magnetic solid‐phase extraction or dispersive liquid–liquid microextraction for pyrethroid determination in environmental samples

The determination of 15 pyrethroids in soil and water samples was carried out by gas chromatography with mass spectrometry. Compounds were extracted from the soil samples (4 g) using solid–liquid extraction and then salting‐out assisted liquid–liquid extraction. The acetonitrile phase obtained (0.8 mL) was used as a dispersant solvent, to which 75 μL of chloroform was added as an extractant solvent, submitting the mixture to dispersive liquid–liquid microextraction. For the analysis of water samples (40 mL), magnetic solid‐phase extraction was performed using nanocomposites of magnetic nanoparticles and multiwalled carbon nanotubes as sorbent material (10 mg). The mixture was shaken for 45 min at room temperature before separation with a magnet and desorption with 3 mL of acetone using ultrasounds for 5 min. The solvent was evaporated and reconstituted with 100 μL acetonitrile before injection. Matrix‐matched calibration is recommended for quantification of soil samples, while water samples can be quantified by standards calibration. The limits of detection were in the range of 0.03–0.5 ng/g (soil) and 0.09–0.24 ng/mL (water), depending on the analyte. The analyzed environmental samples did not contain the studied pyrethroids, at least above the corresponding limits of detection.     

Temperature‐controlled ionic liquid‐dispersive liquid‐phase microextraction for preconcentration of chlorotoluron,diethofencarb and chlorbenzuron in water samples

This article describes a new, rapid and sensitive method for the determination of chlorotoluron, diethofencarb and chlorbenzuron from water samples with temperature‐controlled ionic liquid‐dispersive liquid‐phase microextraction. In the preconcentration procedure, ionic liquid 1‐hexyl‐3‐methylimidazolium hexafluorophosphate [C₆MIM] [PF₆] was employed as the extraction solvent. The parameters, such as volume of [C₆MIM] [PF₆], sample pH, extraction time, centrifuging time, temperature and salting‐out effect, were investigated in detail. Under the optimal extraction conditions, it has been found that three analytes had excellent LODs (S/N=3) in the range of 0.04–0.43 μg/L. The RSDs (n=6) were in the range of 1.3–4.7%. The proposed method was evaluated with lake water, tap water and melted snow water samples. The experimental results indicated that the proposed method had excellent prospect and would be widely used in the future.     

Electromembrane extraction and capillary electrophoresis with capacitively coupled contactless conductivity detection: Multi‐extraction capabilities to analyses trace metals from saline samples

Simultaneous electromembrane extraction (EME) of six trace metal cations (Cu²⁺, Zn²⁺, Co²⁺, Ni²⁺, Pb²⁺, Cd²⁺) from saline samples was investigated. CE with capacitively coupled contactless conductivity detection (C⁴D) was used to determine the metals in acceptor solutions due to its excellent compatibility with the minute volumes of acceptor solutions. Bis(2‐ethylhexyl)phosphate (DEHPA) was selected as a suitable nonselective modifier for EME transport of target metal cations. Both, the individual effect of each major inorganic cation (Na⁺, K⁺, Ca²⁺, Mg²⁺) and their synergistic effect on EME of the trace metal cations were evaluated. In both cases, a decrease in extraction efficiency was observed when major inorganic cations were present in the sample. This effect was more significant for Ca²⁺ and Mg²⁺. The system was optimized for simultaneous extractions of the six target metals from saline samples (50 mM Na⁺, 5 mM Mg²⁺, 1 mM K⁺, and 1 mM Ca²⁺) and following EME conditions were applied. Organic phase consisted of 1‐nonanol containing 1% (v/v) DEHPA, acceptor solution was 1 M acetic acid (HAc) and sample pH was adjusted to 5. Sample was stirred at 750 rpm and EMEs were carried out at extraction potential of 10 V for 20 min. The method presented a repeatability between 8 and 21.8% (n = 5), good linearity in 0.5–10 μM concentration range (R² = 0.987‐0.999) and LOD better than 2.6 nM. Applicability of the EME–CE–C⁴D method to the analyses of metal cations in drinking water, seawater, and urine samples was also demonstrated.     

Dissolvable layered double hydroxide nanoadsorbent‐based dispersive solid‐phase extraction for highly efficient and eco‐friendly simultaneous microextraction of two toxic metal cations and two anionic azo dyes in real samples

For the first time, a new mode of dispersive solid‐phase extraction is presented as a simple, rapid, adsorbent‐free and environmentally friendly method for the simultaneous microextraction and preconcentration of trace amounts of two metal ions (Pb²⁺ and Cr³⁺) and two anionic azo dyes (reactive yellow 15 (RY15) and reactive black 5 (RB5)). This method is based upon the in situ formation of a layered double hydroxide (LDH) nanosorbent through an electrostatic induction process. In this method, extraction of the analytes is performed simultaneously with the formation of the nanosorbent only by adding hydroxide ions. After extraction and separation of the sorbent from the sample solution through a syringe nanofilter, the analytes are eluted by dissolving the LDHs in an acidic solution. Finally, the extracted metal cations and anionic azo dyes are directly determined by micro‐sampling flame atomic absorption spectrometry and micro‐volume UV–visible spectrophotometry, respectively. Under the optimal experimental conditions including 20 μmol of hydroxide ions, 248.4:20.8 μg l^?1 of M²⁺:M³⁺ ions, 12 cycles of air agitation and 200 μl of CF₃COOH (2 M), good linearities were obtained for Pb²⁺, Cr³⁺, RY15 and RB5 in the concentration ranges 50–600, 5.0–280, 30–2500 and 30–2000 ng ml^?1, respectively, with correlation of determinations higher than 0.995. The preconcentration factor for the target analytes was 50 in a 10 ml sample solution. The limits of detection were found to be 15, 1.5, 10 and 10 μg l^?1 for Pb²⁺, Cr³⁺, RY15 and RB5, respectively. The intra‐day and inter‐day precisions were in the ranges 4.3–6.1 and 5.5–6.8%, respectively. Additionally, the presented method is applicable for the analysis of the target analytes in different water samples with reasonable recoveries (>87%).     

Extraction and preconcentration of tylosin from milk samples through functionalized TiO2 nanoparticles reinforced with a hollow fiber membrane as a novel solid/liquid‐phase microextraction technique

The aim of this study was to introduce a novel, simple, and highly sensitive preparation method for determination of tylosin in different milk samples. In the so‐called functionalized TiO₂ hollow fiber solid/liquid‐phase microextraction method, the acceptor phase is functionalized TiO₂ nanoparticles that are dispersed in the organic solvent and held in the pores and lumen of a porous polypropylene hollow fiber membrane. An effective functionalization of TiO₂ nanoparticles has been done in the presence of aqueous H₂O₂ and a mild acidic ambient under UV irradiation. This novel extraction method showed excellent extraction efficiency and a high enrichment factor (540.2) in comparison with conventional hollow fiber liquid‐phase microextraction. All the experiments were monitored at λ_max = 284 nm using a simple double beam UV‐visible spectrophotometer. A Taguchi orthogonal array experimental design with an OA₁₆ (4⁵) matrix was employed to optimize the factors affecting the efficiency of hollow fiber solid/liquid‐phase microextraction such as pH, stirring rate, salt addition, extraction time, and the volume of donor phase. This developed method was successfully applied for the separation and determination of tylosin in milk samples with a linear concentration range of 0.51–7000 μg/L (r² = 0.991) and 0.21 μg/L as the limit of detection.     

Automated hollow‐fiber liquid‐phase microextraction followed by liquid chromatography with mass spectrometry for the determination of benzodiazepine drugs in biological samples

In this study, two‐phase hollow‐fiber liquid‐phase microextraction and three‐phase hollow‐fiber liquid‐phase microextraction based on two immiscible organic solvents were compared for extraction of oxazepam and Lorazepam. Separations were performed on a liquid chromatography with mass spectrometry instrument. Under optimal conditions, three‐phase hollow‐fiber liquid‐phase microextraction based on two immiscible organic solvents has a better extraction efficiency. In a urine sample, for three‐phase hollow fiber liquid‐phase microextraction based on two immiscible organic solvents, the calibration curves were found to be linear in the range of 0.6–200 and 0.9–200 μg L^?1 and the limits of detection were 0.2 and 0.3 μg L^?1 for oxazepam and lorazepam, respectively. For two‐phase hollow fiber liquid‐phase microextraction, the calibration curves were found to be linear in the range of 1–200 and 1.5–200 μg L^?1 and the limits of detection were 0.3 and 0.5 μg L^?1 for oxazepam and lorazepam, respectively. In a urine sample, for three‐phase hollow‐fiber‐based liquid‐phase microextraction based on two immiscible organic solvents, relative standard deviations in the range of 4.2–4.5% and preconcentration factors in the range of 70–180 were obtained for oxazepam and lorazepam, respectively. Also for the two‐phase hollow‐fiber liquid‐phase microextraction, preconcentration factors in the range of 101–257 were obtained for oxazepam and lorazepam, respectively.     

Simple determination of some antidementia drugs in wastewater and human plasma samples by tandem dispersive liquid–liquid microextraction followed by high‐performance liquid chromatography

In this work, a simple method, namely, tandem dispersive liquid–liquid microextraction, with a high sample clean‐up is applied for the rapid determination of the antidementia drugs rivastigmine and donepezil in wastewater and human plasma samples. This method, which is based on two consecutive dispersive microextractions, is performed in 7 min. In the method, using a fast back‐extraction step, the applicability of the dispersive microextraction methods in complicated matrixes is conveniently improved. This step can be performed in less than 2 min, and very simple tools are required for this purpose. To achieve the best extraction efficiency, optimization of the variables affecting the method was carried out. Under the optimized experimental conditions, the relative standard deviations for the method were in the range of 6.9–8.7%. The calibration curves were obtained in the range of 2–1100 ng/mL with good correlation coefficients, higher than 0.995, and the limits of detection ranged between 0.5 and 1.0 ng/mL.     

液液萃取-分散液液微萃取-气相色谱-质谱联用测定纺织废水中痕量禁用偶氮染料

建立了液液萃取-分散液液微萃取-气相色谱-质谱联用技术测定纺织废水中痕量偶氮染料的方法。废水中的偶氮染料在碱性条件下经连二亚硫酸钠还原成芳香胺后,先用叔丁基甲醚液液萃取、盐酸反萃进行预浓缩及净化;再以乙腈-氯苯体系进行分散液液微萃取,气相色谱-质谱测定。对前处理条件进行了优化,考察了酸碱度及盐效应对芳香胺萃取效率的影响,结果表明:液液萃取过程中加入30 g NaCl,分散液液微萃取过程中加入1 mL 5 mol/L的NaOH调节体系至碱性才能达到较好的萃取效率。在优化的实验条件下,21种目标物均呈现良好的线性关系,其中13种芳香胺的线性范围为0.05～10μg/L, 7种芳香胺的线性范围为0.05～5μg/L, 2,4-二氨基苯甲醚的线性范围为20～100μg/L,相关系数为0.996～0.999。20种芳香胺的检出限可达0.05μg/L, 2,4-二氨基苯甲醚检出限为20μg/L。印染、机织、印花等实际废水加标试验表明,方法的回收率为75.6%～115.1%。该方法富集倍数高,检出限低,适用于纺织废水中痕量禁用偶氮染料的检测。