Electrochemically Fabricated Solid Phase Microextraction Fibers and their Applications in Food, Environmental and Clinical Analysis

Pelit, Levent/0000-0001-8090-703X; Pelit, Fusun/0000-0003-0551-664XWOS: 000494943600003Background: Designing an analytical methodology for complicated matrices, such as biological and environmental samples, is difficult since the sample preparation procedure is the most demanding step affecting the whole analytical process. Nowadays, this step has become more challenging by the legislations and environmental concerns since it is a prerequisite to eliminate or minimize the use of hazardous substances in traditional procedures by replacing with green techniques suitable for the sample matrix. Methods: in addition to the matrix, the nature of the analyte also influence the ease of creating green analytical techniques. Recent developments in the chemical analysis provide us new methodologies introducing microextraction techniques and among them, solid phase microextraction (SPME) has emerged as a simple, fast, low cost, reliable and portable sample preparation technique that minimizes solvent consumption. Results: the use of home-made fibers is popular in the last two decades since the selectivity can be tuned by changing the surface characteristics through chemical and electrochemical modifications. Latter technique is preferred since the electroactive polymers can be coated onto the fiber under controlled electrochemical conditions and the film thicknesses can be adjusted by simply changing the deposition parameters. Thermal resistance and mechanical strength can be readily increased by incorporating different dopant ions into the polymeric structure and selectivity can be tuned by inserting functional groups and nanostructures. A vast number of analytes with wide range of polarities extracted by this means can be determined with a suitable chromatographic detector coupled to the system. Therefore, the main task is to improve the physicochemical properties of the fiber along with the extraction efficiency and selectivity towards the various analytes by adjusting the electrochemical preparation conditions. Conclusion: This review covers the fine tuning conditions practiced in electrochemical preparation of SPME fibers and in-tube systems and their applications in environmental, food and clinical analysis

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

WOS: 000331674400015PubMed ID: 24487040A 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 10 mu L of 2-dodecanol for 40 min at 70 degrees C and then, the extracts were injected to GC-MS column by applying 100 kPa 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 0.1 ng mL(-1) level), respectively. LOD value for CP was found 4.8 ng L-1 and for CPO it was found 3.8 ng L-1. This method can easily be adopted by clinical laboratories for the contribution to policies aiming to reduce exposure of pesticides. (C) 2014 Elsevier B.V. All rights reserved.Ege UniversityEge University; TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [212T210]The authors thank to the Ege University and TUBITAK (Project no: 212T210) for financial support

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

WOS: 000324927300061The 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 (C(18)mimBr), on molybdenum ion (Mo(VI)) and pyrogallol red (PGR) complex. The ternary complex of Mo-PGR-C(18)mimBr 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.Ege UniversityEge UniversityAuthors thank Ege University for financial support and Ege University, Centre for R&D and Pharmacokinetic Applications Environmental & Food Analysis Laboratory (ARGEFAR) for ICP-MS measurements. Authors would like to thank Ass. Prof. Armagan Kinal for proof reading

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

WOS: 000314193800009PubMed ID: 23265455A 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. (C) 2012 Elsevier Ltd. All rights reserved.Ege UniversityEge University [2005/Fen/017]; TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [108T660]The authors thank to the Ege University for financial support (Project 2005/Fen/017) and TUBITAK ((Project 108T660)

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

WOS: 000320085300015PubMed ID: 23669608A 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 degrees C and 45 min, 200 degrees C, 600 rpm and 10 g L-1, respectively. Limit of detection was estimated in the range of 0.073-1.659 ng mL(-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. (C) 2013 Elsevier B.V. All rights reserved.Ege UniversityEge University [2010/Fen/033]The authors thank to the Ege University for financial support (Project 2010/Fen/033)

Preparation and Characterization of a Novel Solid-Phase Microextraction Material for Application to the Determination of Pesticides

9th Aegean Analytical Chemistry Days (AACD) -- SEP 29-OCT 03, 2014 -- Chios, GREECEWOS: 000373911300004The preparation and characterization of a novel solid-phase microextraction fiber is reported with application to the determination of pesticides in fruit juice. The fiber was fabricated by electrochemically coating a stainless steel wire with a thin polymeric film of 4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl) benzenamine. The procedure was initiated in 10mL of acetonitrile containing 5.5mg of monomer, 0.1mol NaClO4, and 0.1mol LiClO4 by cycling the potential between -0.5 and 1.2V with a scan rate of 100mV/sec. The morphology of the fiber surface was examined by scanning electron microscopy and its stability was characterized by thermal gravimetric analysis. The fiber was exposed to headspace extraction of bromopropylate, chlorpyrifos, lambda-cyhalothrin, penconazole, and procymidone prior to the analysis by gas chromatography with an electron capture detector. Operational parameters affecting the extraction efficiency, adsorption and desorption times and temperature, and stirring rate were screened using a Plackett-Burman Design. Emerging parameters were further optimized via Central Composite Design that were 20min at 64 degrees C for adsorption and 4.4min at 250 degrees C for desorption. Solution parameters were optimized to be 5.0mL of sample in pH 2.0 Britton-Robinson buffer containing 0.1mg/L NaCl to promote the volatilization of the analytes. The limits of detection were at the ng/mL level for the pesticides. The fiber was used as a selective and sensitive tool for the trace determination of these pesticides in grape juice

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

9th Aegean Analytical Chemistry Days (AACD) -- SEP 29-OCT 03, 2014 -- Chios, GREECEWOS: 000373911300003A 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 0.1mol NaClO4 containing thiophene and montmorillonite clay dispersed in acetonitrile. Electrochemical deposition was maintained by cycling the potential from -0.2 to +2.2V at a scan rate of 50mV/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