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Ionic liquid intercalated clay sorbents for micro solid phase extraction of steroid hormones from water samples with analysis by liquid chromatography–tandem mass spectrometry

Clay material plays an important role in the transport and retention of many compounds in the soil, therefore, clay based sorbents are promising alternatives for selective sorption of organic pollutants. In the present work, different chain length ionic liquids (ILs) namely, 1-methyl-3-octyl-imidazolium bromide, 1-methyl-3-undecyl-imidazolium bromide and 1-methyl-3-octadecyl-imidazolium bromide were intercalated in the galleries of montmorillonite (MMT) clay. Then, this novel nanofiller surface was utilized in micro extraction of estrogenic hormones for the first time. A fast procedure where sonication-assisted emulsification microextraction combined with vortex assisted micro-solid phase extraction (μ-SPE) was developed for the LC-MS/MS analysis of estrone (E1), 17β-estradiol (E2), estriol (E3) and ethynylestradiol (EE2). The parameters related to the μ-SPE procedure namely; pH, sorbent amount, extraction solvent type and volume, sonication and vortex time, sample volume and salt effect on the extraction efficiency were screened by applying Plackett-Burmann design. The selected parameters were then optimized by using Box-Behnken design. The method was validated for the determination of estrogenic hormone residues in river water samples. Linear calibration plots were obtained for all hormones whose regression coefficients were larger than 0.98. RSD values were found less than 10% for three levels of concentration. LOD levels were calculated as; 0.012, 0.062, 0.018 and 0.693 ng L(-1) for E1, E2, E3 and EE2, respectively. Recovery values were calculated in the range of 86.9-97.7%. Considering large sample volumes required for attaining low limits of these hormones, present method provides an ease for analyst as 10 mL of the sample is adequate for achieving the same sensitivity.

A novel polythiophene – ionic liquid modified clay composite solid phase microextraction fiber: Preparation, characterization and application to pesticide analysis

This report comprises the novel usage of polythiophene - ionic liquid modified clay surfaces for solid phase microextraction (SPME) fiber production to improve the analysis of pesticides in fruit juice samples. Montmorillonite (Mmt) clay intercalated with ionic liquids (IL) was co-deposited with polythiophene (PTh) polymer coated electrochemically on an SPME fiber. The surface of the fibers were characterized by using scanning electron microscopy (SEM). Operational parameters effecting the extraction efficiency namely; the sample volume and pH, adsorption temperature and time, desorption temperature and time, stirring rate and salt amount were optimized. In order to reveal the major effects, these eight factors were selected and Plackett-Burman Design was constructed. The significant parameters detected; adsorption and temperature along with the stirring rate, were further investigated by Box-Behnken design. Under optimized conditions, calibration graphs were plotted and detection limits were calculated in the range of 0.002-0.667ng mL(-1). Relative standard deviations were no higher than 18%. Overall results have indicated that this novel PTh-IL-Mmt SPME surface developed by the aid of electrochemical deposition could offer a selective and sensitive head space analysis for the selected pesticide residues.

Preparation and characterization of sodium dodecyl sulfate doped polypyrrole solid phase micro extraction fiber and its application to endocrine disruptor pesticide analysis.

A robust in house solid-phase micro extraction (SPME) surface has been developed for the headspace (HS)-SPME determination of endocrine disruptor pesticides, namely, Chlorpyrifos, Penconazole, Procymidone, Bromopropylate and Lambda-Cyhalothrin in wine sample by using sodium dodecylsulfate doped polypyrrole SPME fiber. Pyrrole monomer was electrochemically polymerized on a stainless steel wire in laboratory conditions in virtue of diminishing the cost and enhancing the analyte retention on its surface to exert better selectivity and hence the developed polymerized surface could offer to analyst to exploit it as a fiber in headspace SPME analysis. The parameters, mainly, adsorption temperature and time, desorption temperature, stirring rate and salt amount were optimized to be as 70°C and 45min, 200°C, 600rpm and 10gL(-1), respectively. Limit of detection was estimated in the range of 0.073-1.659ngmL(-1) for the pesticides studied. The developed method was applied in to red wine sample with acceptable recovery values (92-107%) which were obtained for these selected pesticides.

Development of a gas chromatographic method for the determination of Chlorpyrifos and its metabolite Chlorpyrifos-oxon in wine matrix

A reliable method has been developed for the determination of Chlorpyrifos (CP) and its metabolite Chlorpyrifos-oxon (CPO) in wine sample using pulsed splitless technique coupled with gas chromatography by using electron capture detector. In this study, a quick, easy and cheap sample preparation method (QuEChERS) based on liquid extraction with acetonitrile, followed by dispersive solid phase extraction using primary secondary amine was tested for the separation and quantification of CP and CPO in wine samples. The accuracy of the developed method was tested upon recovery studies and it was calculated as (92.3 ± 18.2)% for CP and (96.6 ± 16.1)% for CPO. LOD and LOQ values of CP were found as 0.04 and 0.15 ng/mL and 0.49 and 1.62 ng/mL for CPO respectively. By using the pulsed splitless injection mode, the sensitivity of the determination of CP and its metabolite CPO in wine samples was improved compared to splitless technique. CP content of analyzed wine sample was found as 2.05 ± 0.15 ng/mL with a RSD of 7.6% and CPO content was found as 4.99 ± 0.15 ng/mL with a RSD of 3.0% (n=3). The expanded measurement uncertainties were calculated as 17% and 6% for CP and CPO, respectively.

A spectrophotometric method for determination of molybdenum in water samples by using pyrogallol red and a water soluble ionic liquid

The present study describes a simple and sensitive spectrophotometric method for the determination of molybdenum in real water samples. The method is based on the hyperchromic and bathochromic effect of an ionic liquid namely, 1-methyl-3-octadecyl-imidazolium bromide (C18mimBr), on molybdenum ion (Mo(VI)) and pyrogallol red (PGR) complex. The ternary complex of Mo–PGR–C18mimBr displays a distinct absorption peak with excellent analytical characteristics and offers the advantages of simplicity for the determination of Mo(VI) ions, without any need for a solvent extraction step. The limit of detection (LOD) and limit of quantification (LOQ) of the method were calculated as 0.74 ng mL−1 and 2.47 ng mL−1 respectively. The method was validated and applied successfully to the determination of Mo(VI) ions in real water samples. The interference of ferric ions was shown to be removed from samples with less ionic content by using an ion exchange resin prior to the analysis, and the performance of the method was compared with that of ICP-MS.

Application of solidified floating organic drop microextraction method for biomonitoring of chlorpyrifos and its oxon metabolite in urine samples.

A simple, efficient and green analytical procedure for monitoring sub ppb amounts of chlorpyrifos (CP) and chlorpyrifos-oxon (CPO) in urine samples was reported. The methodology is based on the solidified floating organic drop microextraction of the analytes with a free microdrop of 2-dodecanol. The parameters those can affect the microextraction efficiency, such as solvent type, extraction solvent volume, extraction time and temperature, salt effect, pH and stirring rate on extraction were optimized. The analytes were extracted from the urine samples by using 10μL of 2-dodecanol for 40min at 70°C and then, the extracts were injected to GC-MS column by applying 100kPa injection pressure. The regression coefficients relating to linearity were at least 0.99. The accuracy of the developed method was tested upon recovery studies for CP and CPO calculated as 100±7% and 110±9% (at 0.1ngmL(-1) level), respectively. LOD value for CP was found 4.8ngL(-1) and for CPO it was found 3.8ngL(-1). This method can easily be adopted by clinical laboratories for the contribution to policies aiming to reduce exposure of pesticides.

Assessment of DFG-S19 method for the determination of common endocrine disruptor pesticides in wine samples with an estimation of the uncertainty of the analytical results.

A gas chromatographic method for the determination of endocrine disruptor pesticides (Chlorpyrifos, Penconazole, Procymidone, Iprodione, Bromopropylate and Lambda-Cyhalothrin) in wine samples is described. A general DFG-S19 method for residual pesticide determination in all kind of food stuff was investigated to simplify and adopt for wine samples in this work. Alternative sample preparation routes were elucidated and compared according to their recovery values. Four different separation techniques were tested and the method employing florosil column after a LLE procedure was applied for wine samples with satisfactory recovery ratios (72-97%). The pesticides were extracted from the sample by cyclohexane-ethyl acetate mixture (1:1 v/v) and cleaned up by florosil column. The regression coefficients were at least 0.99 and relative standard deviations were no higher than 16%. Detection limits were in the range of 0.6-2.9 ng/mL and the relative expanded measurement uncertainties were calculated in the 7-22% range.

Ionic liquid intercalated clay nanofillers for chromatographic applications

In this study, the preparation and characterization of ionic liquid (IL) intercalated montmorillonite (MMT) and their application as a micro-solid phase extraction material for the determination of Chlorpyrifos (CP) pesticide in water samples were reported. The ionic liquids bearing different chain lengths [1-methyl-3-octylimidazolium bromide (C8mimBr), 1-methyl-3-undecyl-imidazolium bromide (C12mimBr) and 1-methyl-3-octadecyl-imidazolium bromide (C18mimBr)] were intercalated in the galleries of MMT. The IL-intercalated MMTs were characterized by means of XRD and TG methods. The (C12mimBr)-intercalated MMT had the highest sorption efficiency for the CP, which was 32 times higher than the original MMT. We also optimized the parameters for extracting CP from the (C12mimBr)-intercalated MMT.

A green photometric method for determination of mercuric ions in saline samples by a single-drop microextraction technique

This study describes a rapid, simple and sensitive spectrophotometric method for determination of Hg(II) ions in saline samples by a single-drop microextraction (SDME) technique. The method is based on the extraction of dithizone (DTZ) complex of mercury(II) into an undecanol droplet which serves as the organic phase, and then the absorbance of the colored complex is measured at 490 nm by using a microvolume quartz cuvette. This procedure provides a simple, rapid, cost-efficient and, most of all, a green method for detecting mercuric ions by minimizing the organic solvent consumption. A variety of parameters affecting the signal, such as pH, DTZ concentration, sample and extraction solvent volume, extraction time and temperature and salt effects were optimized. Under optimized conditions the linear range was found between 3.2 × 10−8 and 5.0 × 10−7 mol L−1 (6.4–100.8 μg L−1) and the detection limit was calculated as 9.6 × 10−9 mol L−1 (1.9 μg mL−1) attained by a high enrichment factor of 203. The performance and accuracy of the method were compared with those of atomic fluorescence spectrometry. Validation of the proposed method was performed for determination of mercury in saline samples including sea water, mineral water, thermal spring water, and table and rock salt samples, which is difficult to analyze by conventional methods.

Polythiophene–Clay Composite Solid-Phase Microextraction Fiber: Preparation, Characterization, and Application to the Determination of Methanol in Biodiesel

ABSTRACT A novel polymer-clay composite solid phase microextraction fiber is reported for the adsorption of methanol in biodiesel with subsequent determination by gas chromatography coupled with a flame ionization detector. The fiber was fabricated using a stainless steel wire that was subjected to electropolymerization in 0.1 mol NaClO4 containing thiophene and montmorillonite clay dispersed in acetonitrile. Electrochemical deposition was maintained by cycling the potential from −0.2 to +2.2 V at a scan rate of 50 mV/sec. Examination of the surface by scanning electron microscopy revealed that the fiber had a porous surface suitable for the adsorption of volatile analytes. The properties of the fiber were investigated by thermogravimetric analysis and infrared spectroscopy that showed that the clay was inserted in the structure. The fiber was exposed to methanol in biodiesel. The adsorption time, adsorption temperature, and desorption temperature were optimized. Under the optimized conditions, the linear dynamic range for methanol extended from 0.029 to 0.24% (m/m) with a limit of detection of 0.009% (m/m). The method was employed for the analysis of biodiesel and the results were validated with a standard EN 14110 method.