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A simple, fast, and sensitive analytical protocol using fabric-phase sorptive extraction followed by high performance liquid chromatography with ultraviolet detection has been developed and validated for the extraction of five parabens including methylparaben, ethylparaben, propylparaben, butylparaben, and benzylparaben. In the present work, sol-gel polyethylene glycol coated fabric-phase sorptive extraction membrane is used for the preconcentration of parabens (polar) from complex matrices. The use of fabric-phase sorptive extraction membrane provides a high surface area which offers high sorbent loading, shortened equilibrium time, and overall decrease in the sample preparation time. Various factors affecting the performance of fabric-phase sorptive extraction, including extraction time, eluting solvent, elution time, and pH of the sample matrix, were optimized. Separation was performed using a mobile phase consisting of water:acetonitrile (63:37; v/v) at an isocratic elution mode at a flow rate of 0.9 mL/min with wavelength at 254 nm. The calibration curves of the target analytes were prepared with good correlation coefficient values (r2 > 0.9955). The limit of detection values range from 0.252 to 0.580 ng/mL. Finally, the method was successfully applied to various cosmetics and personal care product samples such as rose water, deodorant, hair serum, and cream with extraction recoveries ranged between 88 and 122% with relative standard deviation

By using Schiff base tricarboxylate ligand 5-(4-carboxybenzylideneamino)isophthalic acid (H 3 CIP), a new imine functionalized copper metal organic framework (MOF) has been synthesized solvothermally. It was fully characterized by Fourier Transform Infrared (FTIR) Spectroscopy, Powder X-Ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), and elemental mapping techniques. The as-synthesized MOF has been utilized as fluorescent probe for detection of nitro aromatic explosives (NAEs). The results show that the copper MOF can be developed into highly selective and sensitive sensor for detection of TNP in the aqueous medium via the “turn-off” quenching response. The linear fitting of the Stern-Volmer plot for TNP offered large quenching constant of 1.07 × 10 4 M −1 for Cu-MOF indicating the high sensitivity of the sensing process. Outstanding sensitivity of prepared material towards TNP detection was further validated by the low detection limit of 80 ppb (0.35 µM). The detailed mechanistic studies for their mode of action and density functional theory (DFT) calculations reveals that photo-induced electron transfer (PET) and fluorescence resonance energy transfer (FRET) processes, as well as electrostatic interactions ( i.e. H-bonding) are the key factors for the turn-off response toward TNP by this fluorescent sensor. Thus, this new LMOF owing to their high water stability and remarkable functional features are potential candidates which can be developed into selective and sensitive TNP detection devices.

Various forms of α-amino nitrile molecules are found to exert strong impacts on the synthesis of multiple organic compounds such as pharmaceuticals, amino acids, agrochemical agents, and pesticides. Spherical ZnO nanoparticles (NPs) prepared by a simple co-precipitation method are an efficient heterogeneous catalyst for the synthesis of vital intermediate α-amino nitriles. The present protocol was investigated via one-pot synthesis of α-amino nitriles over ZnO NPs using a three-component coupling reaction of aldehydes, amines, and trimethylsilyl cyanide in acetonitrile. The feasibility of our synthesis approach was assessed with respect to the purity and yield of synthesized products in relation to several controlling variables (e.g., ZnO molar ratio, reaction time, amines/aldehydes types, and solvent). The qualitative characteristics of α-amino nitrile products were evaluated by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), and mass spectroscopic analysis. A high yield (81–95%) of pure α-amino nitriles within a short reaction time (45–75 min) along with good recyclability of the catalyst (e.g., without significant loss in performance over five cycles) was confirmed as the distinctive merits of this new eco-friendly synthetic method. This study confirms that various amines including sterically crowded secondary amines should react efficiently with benzenoid plus non-benzenoid aldehyde to yield α-amino nitriles. The selected route is very fast as well as economical. Hence, this method can be used for large-scale production of a variety of biologically important molecules through α-amino nitriles.

Schiff bases and their metal complexes have become well-known for catalytic (e.g., in various synthetic processes) and biological properties (e.g., antifungal, antibacterial, anti-malarial, and antiviral characteristics) since their discovery by Hugo Schiff in 1864. As synthetic compounds, they are employed as versatile tools in numerous applications such as fluorescent turn-on/turn-off sensors for the determination of diverse analytes (e.g., metallic components). As such, they can offer a way to identify toxic ions and/or to provide their speciation in environmental media. This review covers a broad range of Schiff bases that are used in sensing applications for metallic cations and anions in various kinds of environmental and biological media.

A rapid extraction and cleanup method using selective fabric phase sorptive extraction combined with gas chromatography and mass spectrometry has been developed and validated for the determination of broad polarity spectrum emerging pollutants, ethyl paraben, butyl paraben, diethyl phthalate, dibutyl phthalate, lidocaine, prilocaine, triclosan, and bisphenol A in various aqueous samples. Some important parameters of fabric phase sorptive extraction such as extraction time, matrix pH, stirring speed, type and volume of desorption solvent were investigated and optimized. Calibration curves were obtained in the concentration range 0.05-500 ng/mL. Under the optimum conditions, the limits of detection were in the range 0.009 -0.021 ng/mL. This method was validated by analyzing the compounds in spiked aqueous samples at different levels with recoveries of 93 to 99% and relative standard deviations of

A new ion-selective polyvinyl chloride membrane electrode based on Schiff base [N,N′-bis(1-hydroxynaphthalene-2-carbaldehyde)-o-phenylenediamine] as an ionophore is successfully worked out as sensor for Zn(II) ions. The electrode shows excellent potentiometric response characteristics and displays a linear emf versus log[Zn2+] response over a wide concentration range of 1.0 × 10–7‒0.1 M with nernstian slope of 29.0 ± 0.1 mV/decade with the detection limit of 1.8 × 10–8 M. The sensor exhibits the advantages of fast response time (

In this research, the adsorptive performance of a starch-magnesium/aluminum layered double hydroxide (S-Mg/Al LDH) composite was investigated for different organic dyes in single-component systems by conducting a series of batch mode experiments. S-Mg/Al LDH composite showed preferential adsorption of anionic dyes than cationic dyes. The marked impact of key process variables (e.g., contact time, adsorbent dosage, pH, and temperature) on its adsorption was investigated. Multiple isotherms, kinetics, and thermodynamic models were applied to describe adsorption behavior, diffusion, and uptake rates of the organic dyes over S-Mg/Al LDH composite. A better fitting of the non-linear Langmuir model reflects the predominance of monolayered adsorption of dye molecules on the composite surface. Partition coefficients (mg g−1 μM−1) for S-Mg/Al LDH were observed in the following descending order: Amaranth (665) > Tartrazine (186) > Sunset yellow (71) > Eosin yellow (65). Furthermore, comparative evaluation of the adsorption enthalpy, entropy, and Gibbs free energy values indicates that the adsorption process is spontaneous and exothermic. S-Mg/Al LDH composite maintained a stable adsorption/desorption recycling process over six consecutive cycles with the advantages of low cost, chemical/mechanical stability, and easy recovery. The results of this study are expected to expand the application of modified LDHs toward wastewater treatment.

Using a co-precipitation method, starch-Mg/Al layered double hydroxide (S-Mg/Al LDH) composites were synthesized. Their physicochemical properties were assessed by Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and thermo-gravimetric analysis. The quantification of six non-steroidal anti-inflammatory drugs (NSAIDs) was conducted using real samples (e.g., hospital waste water, river water, sewage treatment plant water, and tablet formulations) by gas chromatography-mass spectrometry. For the development of this method, the system was optimized in terms of several key variables (e.g., pH, flow rate, and eluent type/volume). The developed method for NSAIDs exhibited good resolution, sensitivity, reproducibility, and specificity even in complex matrices with limits of detection between 4 and 20 pg/mL. Hence, S-Mg/Al LDH composites were proven to be efficient and fast solid phase extraction (SPE) sorbents for NSAIDs. In addition, each LDH-SPE cartridge showed good reusability without a noticeable change in performance (e.g., up to 30 cycles) and target recoveries between 99.5 – 82.9 %. This work should open up new opportunities for a sesnsitive and sustainable quantitative method for the determination of NSAIDs in complex samples.

The determination of trace levels of aluminum by high-performance liquid chromatography (HPLC) with UV detection using quercetin, a natural bioactive flavonol, as a metal complexation agent is presented in the current article. The developed method has been successfully applied to the direct determination of aluminum in water samples collected from various sources. A preconcentration technique is indispensable due to the presence of aluminum in environmental water at trace levels. Fabric phase sorptive extraction (FPSE), a relatively new but promising sample preparation technique, was applied to preconcentrate quercetin-Al(III) complex from water samples. Efficient extraction of the quercetin-Al(III) complex from aqueous samples has been accomplished by applying FPSE using a cellulose fabric substrate coated with sol-gel C18 hybrid nanocomposite sorbent. Baseline separation of Al-quercetin complex has been achieved on a reverse phase C18 column with the use of acetonitrile: 3% acetic acid (30:70; v/v) as the mobile phase at a flow rate of 1.0 mL/min. The new FPSE-HPLC-UV method can be used for the routine screening of Al ions in various water samples with high sensitivity, precision and reliability.

Luminescent metal–organic frameworks (LMOFs) are porous crystalline materials consisting of metal clusters and organic linkers. Although LMOFs belong to a subcategory of MOFs, they are superior to typical MOFs in many ways (e.g., in terms of photostability, sensing ability, ease of use, interactions with target analytes, and rapid detection mechanisms). Schiff bases with various desired functionalities can be incorporated into the pore cages of LMOF materials via pre- and post-synthetic modifications. Such functionalities can be used to favorably provide active sites for the selective detection of various target components (e.g., metal ions, anions, biomolecules, explosives, gases, and light molecular weight solvent molecules). This work reviews the recent progress achieved in the development of Schiff base-functionalized LMOF sensors for diverse target substances based on state-of-the-art approaches available for their synthesis.

Metal-organic frameworks (MOFs), built through the interconnection between metal clusters and di- to poly-topic organic linkers, have porous crystalline and tunable structures with many meritful properties such as robustness, high surface area/porosity, and adjustable pore size. As such, MOFs have drawn a great deal of attention in the design of the advanced heterogeneous catalytic materials. As the distribution of the catalytically active sites can be controlled further via post-synthesis modification (PSM), the use of Schiff base for such PSM is considered a promising strategy to develop highly active as well as stable catalysts. The great utility of Schiff base complex-anchored MOF is in fact recognized from various catalytic reactions (e.g., coupling, epoxidation, hydrogenation, and oxidation) through efficient coordination of metal ions. These catalysts are advantageous to overcome the common limitations of both homogeneous catalysis (e.g., poor recyclability as well as reusability) and heterogeneous catalysis (e.g., low activity). This review is hence expected to deliver actionable knowledge for the development of highly effective Schiff base/MOF catalysts via PSM for diverse catalytic applications.

ZnS nanostructures have been synthesized using zinc complexes: Zn(ethyl xanthate) 2 ] & [Zn(morpholine4-dithiocarbamate) 2 ] from ligands potassium ethyl xanthate (KEX) and morpholine4-dithiocarbamate (MDTC) by solvothermal route of synthesis. Crystallographic and morphological analyses of synthesized ZnS nanostructures have been done by X-ray diffraction (XRD) and electron microscopy [Transmission Electron Microscope (TEM)], respectively. Diffraction and electron microscope studies reveal the formation of hexagonal structured ZnS nanocrystals of various morphologies (nanosheets & nanorods). UV–vis. absorption studies have been carried for the detailed optical analyses. Photoluminescence (PL) study was carried out to check luminescence of synthesized ZnS nanostructures in blue region of electromagnetic spectrum. It has been reported that the morphology of synthesized nanostructures strongly depends upon the precursor complexes prepared from two different classes of ligands; potassium ethyl xanthate and morpholine4-dithiocarbamate. Photo-catalytic activity potential of the synthesized ZnS nanostructures has been tested in UV light using methylene blue (MB) dye as a test contaminant in aqueous media. About 88.49% and 87.96% of MB dye was photo-degraded by ZnS nanostructures synthesized from Zn(EX) 2 [ where EX stands for ethyl xanthate] and Zn(MDTC) 2 , respectively.

Cadmium complexes based on Xanthate and dithiocarbamate such as [Cd(ethyl xanthate) 2 ], [Cd(morpholine-4-dithiocarbamate) 2 ] and [Cd(piperazine1-dithiocarbamate) 2 ] have been used as efficient single source precursors. The formation of CdS nanostructures have been achieved by solvothermal route of synthesis. Crystallographic and morphological characterization of synthesized nanomaterials has been done by X-ray diffraction (XRD) and electron microscopy [Transmission Electron Microscope (TEM)], respectively. Diffraction and electron microscope studies reveal the formation of wurtzite structured CdS nanostructures of various morphologies (nanorods and nanospheres). UV–vis absorption and Fourier transform infrared (FTIR) spectroscopic studies have been carried for the detailed optical as well as qualitative analyses. It has been reported that the morphology of synthesized nanomaterials strongly depends upon the type of the precursor complexes. Photo-catalytic activity of the synthesized nanostructures has been tested in visible irradiation using methylene blue (MB) dye as a test contaminant in aqueous media. Morphology dependent photo-catalytic activity of the synthesized nanomaterials has been studied in detail to explore the potential of prepared nanostructures to purify polluted water.

Flavonoids represent an important bioactive component in plants. Accumulation of flavonoids often occurs in plants subjected to abiotic stresses, including the adaptation of plants to the environment and in overcoming their stress conditions. This fact makes their analysis and determination an attractive field in food science since they can give interesting information on the quality and safety of foods. In this study, we discuss reports on plants flavonoids biosynthesis against abiotic stresses and advances in analytical capillary electrophoresis used for their identification and quantification in plants.

Diabetic complications (DC) follow multiple pathophysiological pathways and one of the key pathways is the polyol pathway which involves the metabolism of glucose via aldose reductase (ALR2) and sorbitol dehydrogenase (SDH). ALR2 inhibitors such as epalrestat has already been established as promising candidates for the management of DC. On the basis of pathophysiological understanding of polyol pathway, simultaneous inhibition of ALR2 and SDH may be expected to provide synergistic outcomes in the treatment strategies for DC. Thus, in this study, dual inhibitors of ALR2 and SDH were identified using pharmacophore-based virtual screening. For this purpose, the pharmacophore model for SDH (model ID: AAADH.343) was generated and validated. For screening against ALR2, the pharmacophore model (model ID: AADRR.1109) which was previously reported by our group was applied. Initially, flavones reported by our research group were screened by those two pharmacophore models to obtain hits with an optimum affinity for the catalytic domain of both ALR2 and SDH. Inhibitory potential of identified hits for ALR2 and SDH were then experimentally determined using enzymatic assays reported in the literature. Additional focus was laid on the selectivity of the designed molecules towards ALR2 over ALR1, thus evaluation against ALR1 was also performed. Overall, four molecules FLV-2, FLV-11, FLV-12, and FLV-15 were found to possess significant dual inhibitory activity against ALR2 and SDH, with selectivity over ALR1. Among them, FLV-2 displayed significant dual inhibitory potential with an IC50 value of 0.689 ± 0.018 µM and 0.174 ± 0.003 µM against ALR2 and SDH respectively with a selectivity index of 52.902 to ALR2 over ALR1.

In this research, an efficient (94.9–99.4%) and fast (5 min) method has been developed and validated for simultaneous identification and quantification of phenolic endocrine disrupting compounds with an emphasis on bisphenol A (BPA) and 4-cumylphenol (4-CP) in food stuffs using a dual-template magnetic, molecularly-imprinted polymer (dt-MMIP). The dt-MMIP was synthesized by a sol-gel method using Fe3O4@SiO2 (as the core) and BPA and 4-CP (as templates). The dt-MMIP was coupled with magnetic solid phase extraction to simultaneously detect BPA and 4-CP in food samples. BPA was measured from bottled water and fruit juice samples samples at 0.36 and 0.24 ng mL−1, respectively, while 4-CP in those samples was 0.33 and 0.16 ng mL−1, respectively. Their detection limits were estimated as 0.04 and 0.05 ng mL−1, respectively. The developed dt-MMIP method was highly reproducible, while maintaining a good cyclability up to 20 cycles.

The lithiation of 2,4-lutidine (1) with non-nucleophilic bases, such as lithium diisopropylamide (LDA) and lithium diethylamide (LDEA) affords different regioisomers under similar reaction conditions. The mechanism of these reactions and the factors determining selectivity have not been well understood. The present endeavor explores experimental and quantum chemical approaches to investigate factors that determine regioselectivity of the reaction. It has been found that transition states of LDA/LDEA determine regioselectivity and the presence of acatalyst (LiCl) plays a vital role. The LDA mediated lithiation of 1 proceeds through a disolvated open dimer of LDA, leading to a 2-methyl lithiated product. LDEA mediated lithiation is dominated by a route involving interception of 1 with a trisolvated monomer-based transition state of LDEA resulting in a 4-methyl lithiated product. The mechanism is supported by LiCl catalyzed reactions. LiCl has also been found to effect a change in selectivity of the lithiation of BF3-complexed 2,4-lutidine.

There is a dire need for development of efficient and sensitive methods to efficiently screen parabens. In this research, we focused on quantification of four parabens (i.e., methylparaben (MP), ethylparaben (EP), propylparaben (PP), and butyl paraben (BP)) using chitosan intercalated nickel/iron layered double hydroxide (CS–Ni/Fe-LDH) composites as solid phase extraction sorbent prior to HPLC-PDA analysis. CS-Ni/Fe LDH composites with a heterogeneous, porous texture, and coral reef-like structure exhibit appealing extraction efficiency for the target parabens due to the enhanced possibility for the formation of hydrogen bonding and hydrophobic interactions. The performance of the composites was assessed and optimized for solid phase extraction of parabens from standard samples and real samples (rose water, cream, toothpaste, hair serum, and sunscreen). The LDH-SPE-HPLC method exhibited a wide linear range (e.g., 100–50,000 ng L−1), good linearity (R2 ≥ 0.999), and good precision (relative standard deviation (RSD)

A method for the determination of Co(II), Ni(II) and Pd(II) in aqueous samples by fabric phase sorptive extraction-high-performance liquid chromatography-UV detection (FPSE-HPLC-UV) is developed. A preconcentration step was necessary due to the trace level concentrations of these elements in aqueous samples. Sol-gel polytetrahydrofuran nanocomposite was selected as the sorbent. All major FPSE parameters were optimized. The limit of detection for Co(II), Ni(II) and Pd(II) morpholino dithiocarbamate complexes were found at much lower concentration level compared with earlier reported data with excellent reproducibility. The new FPSE-HPLC-UV method can be used for routine determination of these metal species in various aqueous environmental samples and in different alloys.

In this study, a quantum chemical model was developed to better account for the properties of a Schiff base, (Z)-1-(thiophen-2-yl-methyleneamino) propane-2-ol, which is derived from thiophene-2-carboxy aldehyde and 1-amino-2-propanol. To predict its molecular structure, the assignment of the vibrational wavelength (for FT-IR) and chemical shift (for 1HNMR) of (Z)-1-(thiophen-2-yl-methyleneamino) propane-2-ol was performed experimentally and theoretically. All of the theoretical calculations were performed using the Gaussian 09 program package. The theoretically and experimentally obtained results were in good agreement (R2 ≥ 0.99). The energies of the highest occupied and lowest unoccupied molecular orbitals were estimated using B3LYP (Becke three-parameter hybrid functional combined with Lee–Yang–Parr correlation functional)/6-311++G (d, p). Optimization of the structure of (Z)-1-(thiophen-2-yl-methyleneamino) propane-2-ol provided information concerning the stable form of the geometry of the molecule, stoichiometry of the complexes, and thermodynamic parameters (e.g., energy and entropy). The results indicate that the Schiff base formed stable complexes with Ni2+. The energy of the complex was much lower than that of the free Schiff base. The charge distribution values of each atom in the Schiff base were in agreement with the Pauling scale for electronegativity and vibrational wavelength.

Diabetic complications follow multiple pathophysiological pathways involving aldose reductase (ALR2)-mediated polyol pathway, advanced glycation end products (AGEs) and reactive oxygen species formation. Literature suggests ALR2 inhibitors such as epalrestat to possess significant potential in retinopathy and neuropathy. Thus, in this study, multiple pathophysiology directed molecules targeting ALR2, AGEs and free radicals formation were designed using in silico techniques. Initially, database was screened via in silico tools to obtain hits with affinity for the catalytic domain of ALR2. Additional focus was laid on the presence of structural attributes responsible for AGE's inhibitory and anti-oxidant potential. Out of obtained hits, 2-benzoxazolinone scaffold was selected and ten derivatives were synthesized accordingly. Finally, the synthesized molecules were evaluated for their ALR2 and AGEs inhibitory activities along with free radical scavenging potency.

This paper reports a novel fabric phase sorptive extraction-high performance liquid chromatography-ultra violet detection (FPSE-HPLC-UV) method for the simultaneous extraction and analysis of four phenyltin derivatives that include triphenyltin hydroxide, triphenyltin acetate, triphenyltin chloride and tetraphenyltin in environmental water (agricultural waste water and municipal waste water) and canned food samples. The selected analytes were well resolved by Waters Nova pack C18 column (3.9 x 150 mm, 4 µm particle size) in isocratic elution mode within 15 minutes. The new microextraction media has been analytically evaluated using phenyltin derivatives as model compounds. The factors affecting the extraction efficiency of FPSE have been evaluated and the optimum extraction conditions were determined. Under these optimum conditions, the limits of detection (LODs) for sol-gel C18 coated fabric phase sorptive extraction (FPSE) media in combination with HPLC-UV for the analysis of the phenyltin derivatives were in the range of 10-100 ng/mL with high precision (low relative standard deviation) at 10 ng/mL concentration with good absolute recoveries. To the best of our knowledge, this is the first FPSE extraction procedure applied to environmental water and canned food samples for the simultaneous determination of phenyltin derivatives and could be readily adopted as a rapid and robust green analytical tool for routine environmental and food analytical laboratories.

Highly crystalline polyethylene glycol (PEG) coated Tb3+ doped ZnS nanoparticles have been synthesized and successfully used for norfloxacin sensing. The crystallographic and morphological analyses of PEG coated Tb3+ doped ZnS nanoparticles were performed by X-ray diffraction and Transmission electron microscopy, respectively. The confirmation of Tb3+ doping in ZnS host matrix was done by emission spectroscopy and energy dispersive X-ray spectroscopy. Further, the interaction of norfloxacin with PEG coated Tb3+ doped ZnS nanomaterials was confirmed by optical analysis: spectrophotometrically and spectrofluorimetrically. Norfloxacin sensing was measured by luminescence intensity which increased with increase in concentration of norfloxacin in range from 2.0 × 10−9–8.0 × 10−7 mol L−1, with its correlation coefficient 0.9991. The detection limit of proposed method was 0.05 × 10−9 mol L−1. The developed luminescence method was successfully applied for the determination of norfloxacin using PEG coated Tb3+ doped ZnS nanoparticles in urine and pharmaceutical samples.

This paper proposes a novel, fast, reliable and miniaturised analytical protocol for highly sensitive determination of bisphenol A (BPA) in bottled drinking water. This hybrid approach involves a lucid and expeditious combination of micro-extraction in packed syringe (MEPS) with high performance liquid chromatography coupled to an ultra-violet detector (HPLC-UV). The method was developed, optimised and validated for the determination of BPA in commercial bottled drinking water with remarkable sensitivity to picogram quantities of BPA (ppt level). The important parameters of the MEPS procedure affecting the extraction efficiency were optimized and 50 cycles of draw–eject of the sample with a speed of 10 μl s−1 gave a maximum peak area, with a time of 0.998). Precision studies showed % RSD values less than 2% for BPA in all the selected concentrations. The percentage recoveries of BPA were in the range of 97.50–97.57. The limit of detection (LOD) and limit of quantification (LOQ) were 0.0416 pg ml−1 and 0.1248 pg ml−1 for BPA, respectively. The proposed validated method was successfully applied for the quantitative analysis of BPA in real water and beverage samples to the level of 5.40 pg ml−1 to 14.22 pg ml−1, with an acceptable RSD (%) in the range of 3–9 and is suitable for routine monitoring of BPA in bottled drinking water, for regulatory purposes. Furthermore, this method should also allow easy expansion to water quality records for BPA in different water samples and also related compounds like octyl and nonyl phenol as well as bisphenol S and bisphenol F in water.

Fabric phase sorptive extraction (FPSE) combines the advanced material properties of sol–gel derived microextraction sorbents and the flexible and permeable fabric support to create a robust, simple and green sample preparation device. It simultaneously improves the extraction sensitivity, and the speed of the extraction by incorporating high volume of sponge-like porous sol–gel hybrid inorganic–organic sorbents into permeable fabric substrates that is capable of extracting target analytes directly from simple to complex aqueous sample matrices. For the first time, this technique was applied to the trace level determination of selected polycyclic aromatic hydrocarbons (PAHs) in environmental water samples using a non-polar sol–gel C18 coated FPSE media. Several extraction parameters were optimizedto improve extraction efficiency and to achieve high detection sensitivity. Validation tests of spiked samples showed good linearity for four selected PAHs (R2 = 0.9983–0.9997) over a wide range of concentrations (0.010-10ng/mL). Limits of detection (LODs) and quantification (LOQs) were measured at pg/mL levels, 0.1–1 pg/mL and 0.3–3 pg/mL, respectively. Inter- and intra-day precision tests showed variations of 1.1–4.1% for four selected PAHs. Average absolute recovery values were in the range of 88.1–90.5% surpassed the recovery prediction model, with relative standard deviations below 5%. The developed FPSE-HPLC-FLD protocol was finally applied to analyze 8 environmental water samples. Out of four selected PAHs, fluoranthene (Flu) and phenanthrene (Phen) were the most frequently detected in four samples, at concentration levels of 5.6–7.7 ng/mL and 4.1-11 ng/mL, respectively followed by anthracene (Anth) and pyrene (Pyr) in two samples. The newly developed FPSE-HPLC-FLD protocol is simple, green, fast and economical, with adequate sensitivity for trace levels of four selected PAHs and seems to be promising in routine monitoring of water quality and safety.

This study represents a new analytical high-performance liquid chromatography-fluorescence detector method for the determination of Al(III) as Al(III) complex with 8-hydroxyquinoline-5-sulfonic acid in a tap water sample and a coke sample. A micellar liquid chromatographic method is proposed for the determination of aluminum metal in the presence of cetyltrimethylammonium bromide, a cationic surfactant (0.05 M) used for the solubilization of the aluminum complex. The influence of pH and ligand concentration on the formation of the complex was studied by adding a small amount of 0.1 M sodium hydroxide. The metal chelate was detected at λEx 410 nm and λEm 510 nm. This method eliminates the need for addition of reagent or organic modifier to the mobile phase. The complex was analyzed using an Ascentis Express C18 column and a mobile phase consisting of acetonitrile, methanol and water (55 : 30 : 15). Under the optimized conditions, the linear range was 1-200 µg L(-1) and the limit of detection was 0.05 µg L(-1). The method showed a good detector response over the range of interest and was successfully applied for the determination of trace Al(III) in canned coke and water samples containing excess of Mg(II), Ca(II) and other matrices.

As the presence of organic dyes is recognized as the common cause of many environmental problems, it is important to develop an effective strategy to efficiently remove diverse dyes from wastewater. To this end, dodecylsulfate–intercalated layered double hydroxides (DS-Zn/Al LDHs) were synthesized at a Zn/Al molar ratio (2:1) based on urea-hydrolysis followed by ion exchange. The surface of the LDHs was made hydrophobic to increase the adsorption affinity for organic pollutants. The prepared DS-Zn/Al LDHs were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). As observed in UV-spectrophotometric studies, the DS-Zn/Al LDHs exhibited excellent adsorption capacity toward organic dyes (e.g., methyl orange (MO), Congo red (CR), and brilliant green (BG)) compared to previously reported LDHs due to the enhanced surface area provided by the surfactant and its porous nature. The intercalation of DS greatly increased the affinity for organic dyes because of hydrophobic interactions between dye molecules and surfactants. The sorption was observed to depend on concentration of dye, agitation time, and temperature while being less dependent on pH (for 5 ≤ pH ≤ 10). The maximum adsorption capacities for CR, MO, and BG were 149.3, 114.9, and 87.0 mg/g, respectively with their corresponding partition coefficients of 102.3, 62.8, and 17.3 mg/g/μM, respectively. The adsorption isotherms for the dyes were better explained by the Langmuir model than by the Freundlich model. The results further demonstrated the significance of a pseudo-second-order kinetic model. As such, adsorption primarily occurred on a mono layer in the homogeneous surface of the composite. The reusability characteristics of DS-Zn/Al LDHs are also found as their advantageous feature to make the process more economical with the least waste generation. The cost of the DS-Zn/Al LDHs is approximately US$ 2.0 × 102/ton (e.g., based on the material ratio used for their synthesis). The overall results of this study demonstrated the great potential of DS-Zn/Al LDHs for treatment of diverse dyes in effluent systems with high cost-effectiveness.

Fabric phase sorptive extraction, an innovative integration of solid phase extraction and solid phase microextraction principles, has been combined with gas chromatography-mass spectrometry for the rapid extraction and determination of nineteen organochlorine pesticides in various fruit juices and water samples. FPSE consolidates the advanced features of sol-gel derived extraction sorbents with the rich surface chemistry of cellulose fabric substrate, which could extract the target analytes directly from the complex sample matrices, substantially simplifying the sample preparation operation. Important FPSE parameters, including sorbent chemistry, extraction time, stirring speed, type and volume of back-extraction solvent, and back-extraction time have been optimized. Calibration curves were obtained in a concentration range of 0.1&ndash, 500 ng/mL. Under optimum conditions, limits of detection were obtained in a range of 0.007&ndash, 0.032 ng/mL with satisfactory precision (RSD &lt, 6%). The relative recoveries obtained by spiking organochlorine pesticides in water and selected juice samples were in the range of 91.56&ndash, 99.83%. The sorbent sol-gel poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) was applied for the extraction and preconcentration of organochlorine pesticides in aqueous and fruit juice samples prior to analysis with gas chromatography-mass spectrometry. The results demonstrated that the present method is simple, rapid, and precise for the determination of organochlorine pesticides in aqueous samples.

Simultaneous extraction of the morpholino dithiocarbamate (MDTC) chelates of Cr(III) and Cr(VI) ion from aqueous samples was accomplished by applying fabric phase sorptive extraction (FPSE) using a cellulose fabric modified with a sol-gel/polytetrahydrofuran composite. Following extraction, the chelates were separated by HPLC on a reverse phase C18 column with acetonitrile:water (65:35; v/v) as the mobile phase and UV detection at 320 nm. A single peak is found for the Cr(MDTC)3 but two peaks are caused by Cr(VI) due to the formation of the complexes Cr(MDTC)2(OMDTC) and Cr(MDTC)3 (where OMDTC stands for oxy-MDTC). The limits of detection for the Cr(III) and Cr(VI) complexes are 0.001 and 0.003 ng∙mL‾1, respectively. The method can be used for the determination of chromium species in aqueous samples and displays high precision, sensitivity and reliability.

Capillary electrophoresis has recently attracted considerable attention as a promising analytical technique for metal ion separations. Significant advances that open new application areas for capillary electrophoresis in the analysis of metal species occurred based on various auxiliary separation principles. These are mainly due to complexation, ion pairing, solvation, and micellization interactions between metal analytes and electrolyte additives, which alter the separation selectivity in a broad range. Likewise, many separation studies for metal ions have been concentrated on the use of preelectrophoresis derivatization methodology. Approaches suitable for manipulation of selectivity for different metal species including metal cations, metal complexes, metal oxoanions, and organometallic compounds, are discussed, with special attention paid to the related electrophoretic system variables using illustrative examples.

A highly sensitive fourth derivative spectrophotometric method is presented for the residue analysis of ethylenebis dithiocarbamate fungicide Maneb. The fungicide maneb forms a blue complex with sodium molybdate on heating which is studied spectrophotometrically. The method has been successfully applied to maneb determination in wheat grains and soft drinks with high recoveries. The analytical sensitivity of the present method has been found to be 0.0011 μg/mL.

This study presents a fast, accurate and sensitive technique using gas chromatography-mass spectrometry (GC-MS) for the identification and quantification of N-acyl homoserine lactones (AHLs) in the extracts of bacterial strain of Pseudomonas aeruginosa and sputum sample of a cystic fibrosis patient. This method involves direct separation and determination of AHLs by using GC-MS as simultaneous separation and characterization of AHLs were possible without any prior derivatiza-tion. Electron ionization resulted in a common fragmentation pattern with the most common fragment ion at m/z 143 and other minor peaks at 73, 57 and 43. The limit of detection for N-butanoyl, N-hexanoyl, N-octanoyl, N-decanoyl, N-dodecanoyl and N-tetradecanoyl homoserine lactones was 2.14, 3.59, 2.71, 2.10, 2.45 and 2.34 µg/L, respectively. The presence of AHLs in the culture of P. aeruginosa strain and spu-tum of a cystic fibrosis patient was achieved in selected ion monitoring (SIM) mode by using the prominent fragment at m/z 143.

A new method for the efficient extraction and determination of volatile aliphatic amines by means of single-drop microextraction (SDME) in combination with microchip electrophoresis and contactless conductivity detection has been developed. An experimental approach for interfacing real world samples with chip electrophoresis is presented. The method consists of an optimized protocol for extraction via ultrasound assisted headspace SDME and the separation and determination of the target analytes with a novel microfluidic device. Five volatile, short-chained aliphatic amines, methylamine, dimethylamine, trimethylamine, diethylamine and triethylamine, were determined. The analytes were separated using a PMMA microchip with an 8.7 cm long separation channel and integrated thin-film gold electrodes for capacitively coupled contactless conductivity detection (C4D). The determinations were carried out in a His/MES buffer (His/MES ratio of 80 : 20 at pH 6.6). Various parameters for the extraction and determination of the target analytes were optimized and applied to complex sample matrices like shrimp. The five analytes could be separated in less than 40 s applying a separation voltage of 3.8 kV. A linear concentration dependence was found within the range from 0.1 to 10 ppm for the ethylamine species and from 0.5 to 10 ppm for the methylamines. The limits of detection were all well below 400 ng/mL. The proposed method is simple, quick, presents low levels of waste, works with small sample quantities and is suitable for quantification of aliphatic amines in seafood samples like shrimp or fish from where they are naturally developing upon biodegradation. In the present study the accelerated decay of shrimp tissue due to improper storage was monitored.

Reaction of 3-chloropropyltriethoxysilane ( 1 ) with sodium azide ( 2 ) in the presence of phase transfer catalyst, tert-butylammonium bromide provided 3-azidopropyltriethoxysilane ( 3 ). This undergoes transesterification reaction with triethanolamine in the presence of KOH to form a new silatrane 3-azidopropylsilatrane ( 4 ). Multinuclear NMR ( 1 H, 13 C and 29 Si), IR and elemental analyses support the structure of novel silatrane 4 . 29 Si NMR indicates the presence of penta-coordinated silicon atom, which is supported by X-ray studies. It revealed that Si is present in distorted trigonal bipyramidal environment with three O atoms in equatorial positions and N atom at one of the apical positions. The second axial position is occupied by long alkyl chain bearing azide moiety. The interaction of Si with N forms a transannular bond having 2.176 A bond length.

A rapid, simple, sensitive and accurate quantitative method has been developed for the determination of eleven nitroaromatic components by solid phase microextraction (SPME) coupled to high performance liquid chromatography (HPLC) with UV detection from aqueous samples. PDMS/DVB resin fiber (60 microm) was used for concurrent extraction of all the analytes from aqueous matrix. Static desorption was carried out in the desorption chamber of SPME-HPLC interface containing mobile phase; methanol:water 43:57 (v/v) with subsequent liquid chromatographic analysis at isocratic flow rate of 1.3 mL/min and detection at 254 nm. A reverse phase amide column (5 microm) was used as a separation medium. The limit of detection (S/N=3) for TNT and Tetryl was found to be 0.35 and 0.54 ng/mL, respectively. Developed method has been applied successfully to the analysis of aqueous samples obtained from environmental and industrial sources like river water, ground water, drinking water and industrial waste water.

N-acylated homoserine lactones (AHLs) are produced by Gram-negative bacteria as communication signals and are frequently studied as mediators of the “quorum sensing” response of bacterial communities. AHLs are optically active components and the L-form is known to have activity in the quorum sensing. However, the knowledge regarding the stereospecific production of the AHLs in bacterial cultures is limited; therefore, there is a need for a fast and easy method for their chiral analysis. A method was developed for the preconcentration of the AHLs using single drop microextraction or liquid-liquid microphase extraction in toluene for their analysis using GC-MS. The performance of the method were determined and discussed for the chiral separation of these autoinducers using a capillary column coated with heptakis-(2,3-di-O-acetyl-6-O-t-butyldimethyl-silyl)-β-cyclodextrin. The salient feature of this study is the demonstration, that Burkholderia cepacia LA3 produced D-decanoyl-homoserine lactone beside L-decanoyl- and L-octaonyl- enantiomers.

A solid-phase microextraction (SPME) method followed by separation with high-performance liquid chromatography and subsequent UV detection was developed for the determination of norfloxacin and enrofloxacin. The simple and sensitive preconcentration technique uses 280 nm wavelength in mobile phase of citrate buffer (0.01 M), pH 3.8, prepared in water (A) and acetonitrile (B), with composition of the mobile phase A:B, 40:60, at a flow rate of 1.0 mL/min. A C18 reversed-phase analytical column (5 m) was selected as separation medium for the technique. To obtain optimum extraction efficiency, several parameters relating to SPME were investigated. The method was linear over the range of 10100 ng/mL for norfloxacin and enrofloxacin with a correlation coefficient (R2) value of 0.9972 and 0.9980 for norfloxacin and enrofloxacin, respectively. Using the SPME method, the detection limits (signal-to-noise ratio 3) are 0.17 and 0.12 ng/mL for norfloxacin and enrofloxacin, respectively.

Conditions have been developed for simultaneous determination of paraquat (PQ) and diquat (DQ) by capillary zone electrophoresis (CZE) with diode array detector (DAD) after their preconcentration by solid phase extraction using Megabond Elut C18 and Strata X 33 μm Polymeric sorbent cartridges. Conditions were optimised with reference to pH, EDTA concentration in sodium acetate acetic acid buffer of pH (3.8) with 3-8 % of methanol, ethanol and acetonitrile as organic modifier in the background electrolyte. UV detection with variable wavelength was used to determine each compound at its maximum absorption providing an excellent sensitivity. The recovery of these compounds from water samples spiked at different levels was more than 90 %. The limit of detection (S/N=3) obtained for milli-Q water when spiked with standards was 0.17 ppm for DQ and 0.19 ppm for PQ, in tap water samples it was found to be 0.27 ppm for DQ and 0.31 ppm for PQ, in cola beverages it was found to be 0.29 ppm for DQ and 0.35 ppm for PQ, and for the urine samples it was 0.36 ppm for diquat and 0.41 ppm for the PQ without preconcentration. After preconcentration using polymeric cartridge the detection limit was reduced to 2.5 ppb for DQand 3 ppb for PQ for the milli-Q water. These detection limits allows for the analysis of these compounds at the levels established by the US Environmental Protection agency.

A highly sensitive solid phase microextraction – high performance liquid chromatographic method has been developed for the determination of copper(II) using morpholine-4-carbodithioate (MDTC) as an analytical reagent. The MDTC formed yellowish- brown species of copper(II) at a pH range of 2-9 and complex was sorbed onto PDMS fiber. The Cu(II)-MDTC complex shows maximum absorbance at 430 nm and can be separated on C18 column by using acetonitrile : water (80 : 20) at a flow rate of 1.0 ml min-1.The detection limit of method was found to be 0.51 μg L-1. The interference due to common metal ions were studied. The repeatability of the method was checked by finding the relative standard deviation. The developed method was successfully employed for the determination of copper(II) in different alloy samples and the results were compared with existing methods.

A new approach has been developed for the extraction and determination of aldehydes such as veratraldehyde, m-nitrobenzaldehyde, cinnamaldehyde, benzaldehyde, and p-chlorobenzaldehyde by using solid-phase microextraction (SPME) and high-performance liquid chromatography with UV detection (HPLC/UV). The method involves adsorption of the aldehydes on polydimethylsiloxane/divinylbenzenecoated fiber, followed by desorption in the desorption chamber of the SPME-HPLC interface, using acetonitrilewater (70 + 30) as the mobile phase; UV detection was at 254 nm. A good separation of 5 aldehydes was obtained on a C18 column. The detection limits of veratraldehyde, m-nitrobenzaldehyde, cinnamaldehyde, benzaldehyde, and p-chlorobenzaldehyde are 25, 41, 13, 12, and 11 pg/mL, respectively, which are about 100 times better than the detection limits for other SPME methods using gas chromatography. The proposed method was validated by determining benzaldehyde in bitter almonds and cinnamaldehyde in cinnamon bark. The recoveries of the 5 analytes were determined by analysis of spiked drinking water.

A selective, sensitive, and economical derivative spectrophotometric method has been developed for the determination of trace amount of Cu(II) and Pd(II) with MDTC as a reagent in the presence of CTAB, a solubilizing agent. The molar absorption coefficient and analytical sensitivities of the 1:2 Cu(MDTC)2 and Pd(MDTC)2 complexes are 2.467×104 and 2.989×104 l mol−1, respectively. The developed derivative procedure, is applied for the rapid and selective simultaneous determination of Cu(II) and Pd(II) in the range of 0.2–15 and 0.1–10 µg/ml, respectively. Complex matrices, including alloys, biological samples, pharmaceutical samples and synthetic mixtures have been successfully analyzed for trace amounts of two metal ions.

A new approach for the analysis of Co(II), Ni(II) and Pd(II) as morpholine-4-carbodithioate (MDTC) complexes in aqueous medium by using solid phase microextraction (SPME)–high performance liquid chromatography (HPLC)–UV has been developed. The method involves sorption of metal complexes on PDMS fiber from aqueous solution followed by desorption in the desorption chamber of SPME–HPLC interface using acetonitrile:water (60:40) as mobile phase. A good separation of metal complexes is achieved on C18 column. The detection limits of Co(II), Ni(II) and Pd(II) are 0.17, 0.11 and 0.06 ng ml−1, respectively. These can be determined by the proposed method without interference from other common metal ions such as Mo(VI), V(V), Ag(I), Sn(IV), Cd(II), Pb(II), Zn(II), Ag(I), Sn(II), Cr(III) and Cr(VI). The method was applied to the determination of these metals in different alloy samples and drinking water sample.

A simple and sensitive capillary electrophoretic method with ultraviolet detection has been developed for the separation and determination of ferbam [iron(III)-dimethyldithiocarbamate], maneb [manganese(II)-ethylenebisdithiocarbamate] and zineb [zinc(II)-ethylenebisdithiocarbamate], in borate buffer, after their acidic decomposition and complexation with CDTA (trans-1,2-diaminocyclohexane-N,N,N,N-tetraacetic acid monohydrate), as CDTA-metal complexes of Fe+3, Mn+2, and Zn+2. The determination is dependent on the pH and the nature of the buffer solutions. In this method, the detection limit (signal-to-noise ratio = 3) is 0.0013, 0.0022, and 0.0023 mM for ferbam, maneb, and zineb, respectively. The relative standard deviation for the analysis of 1 mM of each was found to be 1.5 0.2%. The method was successfully applied for the analysis of red beans and grain samples spiked with ferbam, maneb, and zineb. The applicability of capillary electrophoresis as a useful tool for the simultaneous determination and analysis of ferbam, maneb, and zineb is demonstrated.

This paper reviews recent developments of solid phase microextraction (SPME) and its application to the analysis of organometallic species of lead, arsenic, mercury, tin, and selenium by hyphenation with HPLC-GC-atomic spectrometry. In the first part, a background of the technique is given in terms of derivatization, fibers used, extraction and desorption conditions. The second part summarizes typical SPME applications to the determination of organometallic species and the main experimental conditions with the aid of specific examples. Most of the applications comprise alkylation with NaBEt4 and headspace extraction followed by gas chromatographic separation with a suitable detector.

A procedure has been developed for the direct fourth derivative spectrophotometric determination of tetramethyldithiocarbamate by converting it into its molybdenum complex, which is then extracted in to methyl isobutyl ketone (MIBK). Beer's law is obeyed over the concentration range 24mugmL(-1) in the final solution. The analytical sensitivity is calculated to be 0.004(d(4)A/dlambda(4)) mug(-1)mL(-1) from the slope of the calibration curve. The detection limit is 0.3mugmL(-1) for thiram (signal to noise ratio = 2). Various parameters, such as effect of acid concentration, interference of a large number of ions in the determination of thiram have been studied in detail. The method is sensitive, highly selective and can be used for the determination of thiram in a commercial sample, in mixtures with various dithiocarbamates (zineb, maneb, etc.) and from wheat grains.

A procedure has been developed for the direct fourth derivative spectrophotometric determination of zinc(II) dimethyldithiocarbamate by converting it into its copper(II) dimethyldithiocarbamate complex, which is then dissolved in Triton X-100. Beer's law is obeyed over the concentration range 0.5–30 µg/mL in the final solution. Various parameters such as the effect of pH and the interference of a number of ions on the determination of Ziram have been studied in detail. The method is sensitive and can be used for the determination of Ziram in commercial samples like Zirax and Ziron containing Ziram and from wheat grains.

A procedure has been developed for the direct fourth-derivative spectrophotometric determination of iron(III) dimethyldithiocarbamate by converting it into an iron(II) 2,2'-bipyridyl complex, which is then dissolved in Triton X-100. Beer's law is obeyed over the concentration range 0.5-20 microg mL(-1 )in the final solution. Various parameters such as the effect of pH and interference of large number of ions on the determination of ferbam have been studied in detail. The method is sensitive, highly selective and can be used for the determination of ferbam in a commercial sample and in mixtures with various dithiocarbamates (ziram, zineb, maneb, etc.) and from wheat grains.

A simple, fast and sensitive analytical method using fabric phase sorptive extraction (FPSE) followed by high performance liquid chromatography with fluorescence detection (HPLC-FLD) has been developed for efficient quantification of biologically important molecules e.g., 17α-ethynylestradiol (EE2), β-estradiol (E2) and bisphenol A (BPA). FPSE is a new sorptive extraction technique that integrates the advantages of permeable sol-gel derived hybrid organic-inorganic sorbents with flexible and permeable fabric substrates, resulting in a highly efficient and sensitive extraction media that can be introduced directly into any kind of fluidic matrix. Various factors affecting the performance of FPSE technique were optimized. The chromatographic separation was carried using mobile phase acetonitrile/methanol/water (30:15:55; v/v) at a flow rate 1.0mL/min on C18 column with fluorescence detection (λex=280nm and λem=310nm). The calibration curves of the target analytes were prepared with good correlation coefficient values (R(2)>0.992). Limit of detection (LOD) values range from 20 to 42pg/mL. The developed method was applied successfully for the analysis of estrogen molecules in urine and various kinds of aqueous samples.

A procedure has been developed for the determination of iron(III) dimethyldithiocarbamate by converting it into the iron(II)−bathophenanthroline complex, which is then dissolved in acetone−water (1:1), and the absorbance is measured at 534 nm against a reagent blank. Beer's law is obeyed over the concentration range 0.5−20 μg mL-1 in the final solution. The method is sensitive and highly selective and is used for the direct determination of ferbam in a commercial sample and in mixtures with various dithiocarbamates (ziram, zineb, maneb, etc.) and from wheat grains. Keywords: Spectrophotometry; ferbam; commercial sample; bathophenanthroline