Capacitance Polypyrrole‐based Impedimetric Immunosensor for Interleukin‐10 Cytokine Detection

In the present study, we developed a novel label‐free capacitance impedimetric immunosensor based on the immobilization of the human monoclonal antibody anti‐interleukin‐10 (anti‐IL‐10 mAb) onto polypyrrole (PPy)‐modified silicon nitride (Si₃N₄) substrates. The immunosensor was used for the detection of the recombinant interleukin‐10 antigen (rh IL‐10) that may be secreted in patients at the early stage of inflammation. The immunosensor was created by chemical deposition of PPy conducting layer on pyrrole?silane (SPy)‐treated Si/SiO₂/Si₃N₄ substrates (Si/SiO₂/Si₃N₄?SPy), followed by anti‐IL‐10 mAb immobilization through carboxyl‐functionalized diazonium (CMA) protocol and carbodiimide chemistry. The surface characterization and the biofunctionalization steps were characterized by SEM, FTIR and cyclic voltammetry (CV) while the detection process was carried out by using electrochemical impedance spectroscopy (EIS) analyses. The created immunosensor showed two linear fittings (R²=0.999) for the detection of rh IL‐10 within the concentration range from 1–50 pg/mL. It exhibited high sensitivity (0.1128 (pg/mL)^?1) with a very low limit of detection (LOD)=0.347 pg/mL, more particularly, at the low concentration range (1–10 pg/mL). Thus, this developed polypyrrole‐based immunosensor represents a promising strategy for creation of miniaturized label‐free, fast and highly sensitive biosensors for diagnosis of inflammation biomarkers at very low concentrations with reduced cost.     

Porous‐membrane‐protected polyaniline‐coated SBA‐15 nanocomposite micro‐solid‐phase extraction followed by high‐performance liquid chromatography for the determination of parabens in cosmetic products and wastewater

A SBA‐15/polyaniline para‐toluenesulfonic acid nanocomposite supported micro‐solid‐phase extraction procedure has been developed for the extraction of parabens (methylparaben, ethylparaben, and propylparaben) from wastewater and cosmetic products. The variables of interest in the extraction process were pH of sample, sample and eluent volumes, sorbent amount, salting‐out effect, extraction and desorption time, and stirring rate. A Plackett–Burman design was performed for the screening of variables in order to determine the significant variables affecting the extraction efficiency. Then, the significant factors were optimized by using a central composite design. The optimum experimental conditions found at 50 mL sample solution, extraction and desorption times of 40 and 20 min, respectively, 500 μL of 3% v/v acetic acid in methanol as eluent, 0.01 M salt addition, and 10 mg of the sorbent. Under the optimum conditions, the developed method provided detection limits in the range of 0.08–0.4 ng/mL with good repeatability (RSD% < 7) and linearity (r² = 0.997–0.999) for the three parabens. Finally, this fast and efficient method was employed for the determination of target analytes in cosmetic products and wastewater, and satisfactory results were obtained.     

Membrane protected conductive polymer as micro‐SPE device for the determination of triazine herbicides in aquatic media

A micro‐SPE technique was developed by fabricating a rather small package including a polypropylene membrane shield containing the appropriate sorbent. The package was used for the extraction of some triazine herbicides from aqueous samples. Solvent desorption was subsequently performed in a microvial and an aliquot of extractant was injected into GC‐MS. Various sorbents including aniline‐ortho‐phenylene diamine copolymer, newly synthesized, polypyrrole, multiwall carbon nanotube, C18 and charcoal were examined as extracting media. Among them, conductive polymers exhibited better performance. Influential parameters including extraction and desorption time, desorption solvent and the ionic strength were optimized. The developed method proved to be rather convenient and offers sufficient sensitivity and good reproducibility. The detection limits of the method under optimized conditions were in the range of 0.01–0.04 ng/mL. The RSDs at a concentration level of 0.1 ng/mL were obtained between 4.5 and 9.3% (n=5). The calibration curves of analytes showed linearity in the range of 0.05–10 ng/mL. The developed method was successfully applied to the extraction of selected triazines from real water samples. The whole procedure showed to be conveniently applicable and quite easy to manipulate.     

Electroconductive Hydrogels: Electrical and Electrochemical Properties of Polypyrrole‐Poly(HEMA) Composites

Composites of inherently conductive polypyrrole (PPy) within highly hydrophilic poly(2‐hydroxyethyl methacrylate)‐based hydrogels (p(HEMA)) have been fabricated and their electrochemical properties investigated. The electrochemical characteristics observed by cyclic voltammetry suggest less facile reduction of PPy within the composite hydrogel compared to electropolymerized PPy, as shown by the shift in the reduction peak potential from ?472 mV for electropolymerized polypyrrole to ?636 mV for the electroconductive composite gel. The network impedance magnitude for the electroconductive hydrogel remains quite low, ca. 100 Ω, even upon approach to DC, over all frequencies and at all offset potentials suggesting retained electronic (bipolaronic) conductivity within the composite. In contrast, sustained application of +0.7 V (vs. Ag/AgCl, 3 M Cl^?) for typically 100 min. (conditioning) to reduce the background amperometric current to <1.0 μA, resulted in complete loss of electroactivity. Nyquist plots suggest that sustained application of such a modest potential to the composite hydrogel results in impedance characteristics that resembles p(HEMA) without evidence of the conducting polymer component. PPy composite gels supported a larger ferrocene monocarboxylate diffusivity (D_appt=7.97×10^?5 cm² s^?1) compared to electropolymerized PPy (D_appt=5.56×10^?5 cm² s^?1), however a marked reduction in diffusivity (D_appt=1.01×10^?5 cm² s^?1) was observed with the conditioned hydrogel composite. Cyclic voltammograms in buffer containing H₂O₂ showed an absence of redox peaks for electrodes coated with PPy‐containing membranes, suggesting possible chemical oxidation of polypyrrole by the oxidant     

An interior needle electropolymerized pyrrole-based coating for headspace solid-phase dynamic extraction

A headspace solid-phase dynamic extraction (HS-SPDE) technique was developed by the use of polypyrrole (PPy) sorbent, electropolymerized inside the surface of a needle, as a possible alternative to solid-phase microextraction (SPME). Thermal desorption was subsequently, employed to transfer the extracted analytes into the injection port of a gas chromatography-mass spectrometry (GC-MS). The PPy sorbent including polypyrrole-dodecyl sulfate (PPy-DS) was deposited on the interior surface of a stainless steel needle from the corresponding aqueous electrolyte by applying a constant deposition potential. The homogeneity and the porous surface structure of the coating were examined using the scanning electron microscopy (SEM).The developed method was applied to the trace level extraction of some polycyclic aromatic hydrocarbons (PAHs) from aqueous sample. In order to enhance the extraction efficiency and increase the partition coefficient of analytes, the stainless steel needle was cooled at 5 °C, while the sample solution was kept at 80 °C. Optimization of influential experimental conditions including the voltage of power supply, the time of PPy electrodeposition, the extraction temperature, the ionic strength and the extraction time were also investigated. The detection limits of the method under optimized conditions were in the range of 0.002-0.01 ng mL⁻¹. The relative standard deviations (R.S.D.) at a concentration level of 0.1 ng mL⁻¹ were obtained between 7.54 and 11.4% (n = 6). The calibration curves of PAHs showed linearity in the range of 0.01-10 ng mL⁻¹. The proposed method was successfully applied to the extraction of some selected PAHs from real-life water samples and the relative recoveries were higher than 90% for all the analytes.     

Preparation of NiAl double hydroxide@polypyrrole materials for high‐performance supercapacitors

A novel NiAl double hydroxide@polypyrrole (LDH@PPy) core–shell material was designed and fabricated by a facile in situ oxidative polymerization of pyrrole (Py) monomer. The microstructure and morphology of the LDH@PPy composites were determined by X‐ray diffractometer, Fourier transform infrared (FTIR), scanning electron microscopy/transmission electron microscopy, and thermogravimetric and differential thermal, revealing that the polypyrrole (PPy) was successfully coated onto the surface of the NiAl‐LDH (LDH) core and the loading amount of PPy impacted the thickness and the dispersion of the conductive PPy shell. The electrochemical performances of the LDH@PPy composites were also evaluated by cyclic voltammogram, electrochemical impedance spectroscopy, and galvanostatic charge–discharge measurements. The results indicated that the supercapacitor performances were attributed to the synergy of unique core–shell heterostructure and each individual component, where the LDH core provided the high‐energy storage capacity and the PPy shell with networks had high electronic conductivity. These shorted the ion diffusion pathway and made electrolyte ions more easily accessible for faradic reactions to enhance the electrochemical performance of the LDH@PPy composites. It was found that the LDH@PPy composite (LDH@PPy₇) fabricated at 7 mL?L^?1 of Py monomer feed exhibiting the best electrochemical performances with high specific capacitance of 437.5 F?g^?1 at 2 A?g^?1 and excellent capacitance retention of about 91% after 1000 cycles. The work provides a simple approach for designing organic–inorganic core–shell materials with potential application in supercapacitors. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1653–1662     

以聚吡咯和纳米金为基质基于电化学交流阻抗测试的乙肝表面抗原免疫传感器研究

A novel simple immunosensing strategy for fabrication of hepatitis B surface antigen detection has been developed via electrochemical impedance spectroscopy （EIS） as a platform. At first, the conductive polymer polypyrrole （PPy） film was electrodeposited on a platinum electrode surface to adsorb the gold nanoparticles （nano-Au） via the opposite-charged adsorption technique, and then hepatitis B surface antibodies were adsorbed onto the surface of nano-Au. The modification procedure was characterized by EIS. Such spectroscopy is attributed to the concomitant conductivity changes of the polymerized pyrrole film and gold nanoparticles. The factors influencing the performance of resulting immunoelectrode were studied in detail. The linear range of the resulting immunoelectrode is from 2.6 to 153.6 ng.mL^-1 with a detection limit of 1.3 ng·mL^-1 at 3σ. In addition, the experiment results indicate that antibody immobilized on this way exhibits a good sensitivity, selectivity, high stability and a long-term maintenance of bioactivity, implying a great promising alternative approach for reagentless immunosensing analysis in the clinical diagnosis.     

Solid Phase Extraction of Uranium by Naphthalene‐Methyltrioctylammonium Chloride and Arsenazo(III) Adsorbent and Subsequent Spectrophotometric Determination

A simple and effective method has been presented for the preconcentration of uranium by solid phase extraction. For this purpose arsenazo(III) supported on naphthalene‐methyltrioctylammonium chloride was used as an adsorbent and uranium solution at pH 3.5 with flow rate of 1 mL·min⁻¹ was passed through the column. Therefore, uranium‐arsenazo(III) complex was formed onto column. Uranium was quantitatively eluted with 5 mL of a 0.1% ammonium tetraphenylborate and determined by spectrophotometric method at 652 nm. Several parameters such as pH, amount of reagents, sample volume, etc. were investigated. The effect of diverse ions on the preconcentration has also been studied and the optimized conditions developed have been utilized for the trace determination of uranium. A preconcentration factor of 100 was achieved. The relative standard deviation (N=8) was 0.5% for 3 ng· mL⁻¹ of uranium. The three sigma detection limit (36) was 0.045 ng·mL⁻¹     

Extraction and preconcentration of formaldehyde in water by polypyrrole‐coated magnetic nanoparticles and determination by high‐performance liquid chromatography

In this study, a simple and rapid extraction method based on the application of polypyrrole‐coated Fe₃O₄ nanoparticles as a magnetic solid‐phase extraction sorbent was successfully developed for the extraction and preconcentration of trace amounts of formaldehyde after derivatization with 2,4‐dinitrophenylhydrazine. The analyses were performed by high‐performance liquid chromatography followed by UV detection. Several variables affecting the extraction efficiency of the formaldehyde, i.e., sample pH, amount of sorbent, salt concentration, extraction time and desorption conditions were investigated and optimized. The best working conditions were as follows: sample pH, 5; amount of sorbent, 40 mg; NaCl concentration, 20% w/v; sample volume, 20 mL; extraction time, 12 min; and 100 μL of methanol for desorption of the formaldehyde within 3 min. Under the optimal conditions, the performance of the proposed method was studied in terms of linear dynamic range (10–500 μg/L), correlation coefficient (R² ≥ 0.998), precision (RSD% ≤ 5.5) and limit of detection (4 μg/L). Finally, the developed method was successfully applied for extraction and determination of formaldehyde in tap, rain and tomato water samples, and satisfactory results were obtained.     

Determination of Protoberberine Alkaloids in Coptis chinensis by Microextraction and High Performance Liquid Chromatography

Sample preparation technique based on an organic filter membrane (pH-resolved filter membrane microextraction) (pH-RFMME) was developed, coupled with high-performance liquid chromatography, and used to determine protoberberine alkaloids (jatrorrhizine, epiberberine, coptisine, palmatine, and berberine) in Coptis chinensis at different pH values through a one-step procedure. This green procedure provides a desirable sample pretreatment technology. The main variables affecting the extraction such as filter membrane area (or volumes of extraction solvents), sample pH, eluent pH, ionic strength, extraction stirring rate, extraction time, and sample volume were optimized. Under the optimized conditions, the enrichment factors of the analytes were 40.4–52.0, the linear ranges were 3.2–6250 ng · mL^?1 for jatrorrhizine and epiberberine, 6.0–12000 ng · mL^?1 for coptisine, 1.8–3600 ng · mL^?1 for palmatine, and 18.8–18800 ng · mL^?1 for berberine, with r ² ≥ 0.9945. The limits of detection were less than 0.3 ng · mL^?1. Satisfactory recoveries (84.8%–115.5%) and precision (1.8%–10.0%) were also achieved. These results confirmed that pH-RFMME is a simple, rapid, practical, and environmentally friendly method to isolate analytes that exhibit significant differences in acidity or alkalinity from complex samples.     

Fast Quantitation of Target Analytes in Small Volumes of Complex Samples by Matrix‐Compatible Solid‐Phase Microextraction Devices

Herein we report the development of solid‐phase microextraction (SPME) devices designed to perform fast extraction/enrichment of target analytes present in small volumes of complex matrices (i.e. V≤10 μL). Micro‐sampling was performed with the use of etched metal tips coated with a thin layer of biocompatible nano‐structured polypyrrole (PPy), or by using coated blade spray (CBS) devices. These devices can be coupled either to liquid chromatography (LC), or directly to mass spectrometry (MS) via dedicated interfaces. The reported results demonstrated that the whole analytical procedure can be carried out within a few minutes with high sensitivity and quantitation precision, and can be used to sample from various biological matrices such as blood, urine, or Allium cepa L single‐cells.     

Solid‐phase extraction using bis(indolyl)methane‐modified silica reinforced with multiwalled carbon nanotubes for the simultaneous determination of flavonoids and aromatic organic acid preservatives

A novel bis(indolyl)methane‐modified silica reinforced with multiwalled carbon nanotubes sorbent for solid‐phase extraction was designed and synthesized by chemical immobilization of nitro‐substituted 3,3′‐bis(indolyl)methane on silica modified with multiwalled carbon nanotubes. Coupled with high‐performance liquid chromatography analysis, the extraction properties of the sorbent were evaluated for flavonoids and aromatic organic acid compounds. Under optimum conditions, the sorbent can simultaneously extract five flavonoids and two aromatic organic acid preservatives in aqueous solutions in a single‐step solid‐phase extraction procedure. Wide linear ranges were obtained with correlation coefficients (R²) ranging from 0.9843 to 0.9976, and the limits of detection were in the range of 0.5–5 μg/L for the compounds tested. Compared with the silica modified with multiwalled carbon nanotubes sorbent and the nitro‐substituted 3,3′‐bis(indolyl)methane‐modified silica sorbent, the developed sorbent exhibited higher extraction efficiency toward the selected analytes. The synergistic effect of nitro‐substituted 3,3′‐bis(indolyl)methane and multiwalled carbon nanotubes not only improved the surface‐to‐volume ratio but also enhanced multiple intermolecular interactions, such as hydrogen bonds, π–π, and hydrophobic interactions, between the new sorbent and the selected analytes. The as‐established solid‐phase extraction with high‐performance liquid chromatography and diode array detection method was successfully applied to the simultaneous determination of flavonoids and aromatic organic acid preservatives in grape juices with recoveries ranging from 83.9 to 112% for all the selected analytes.     

Modified Activated Carbon as Solid Phase Extraction Adsorbent for the Preconcentration and Determination of Trace As(III) in Environmental Samples by Graphite Furnace Atomic Absorption Spectrometry

A simple and selective method was developed for the preconcentration, separation, and determination of trace amounts of As(III) in an aqueous solution by solid phase extraction combined with graphite furnace atomic absorption spectrometry. Activated carbon (AC) was modified by sodium diethyldithiocarbamate (NaDDTC) and then used as a new, stable and easily prepared solid sorbent in a mini column for the extraction of As(III) in aqueous solution. Factors influencing the sorption and desorption of As(III), such as volume and concentration of eluent, sample pH, flow rate and effect of interfering ions on the recovery of As(III) have been systemically investigated. At pH 2.0 As(III) could be adsorbed quantitatively by NaDDTC‐AC, and then eluted completely with 2 mL of 3.0 mol·L^?1 HNO₃. The amount of eluted As(III) was measured using graphite furnace atomic absorption spectrometry. The detection limit of As(III) was 0.04 ng·mL^?1 with enrichment factor of 100 and the relative standard deviation (RSD, n=8) was 1.58% at 10 ng·mL^?1 level.     

Analysis of Dried Blood Spots for Polychlorinated Biphenyls and Organochlorine Pesticides by Gas Chromatography Coupled with Tandem Mass Spectrometry

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCs) are anthropogenic pollutants highly resistant to chemical degradation and readily absorbed by organic tissue. Their persistence in the environment and toxicological threat to mammals prompts swift, reliable methods of analysis. This study outlines a rapid, efficient and sensitive, validated methodology utilizing a simple liquid extraction technique, and subsequent analysis by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) for the determination of PCBs and OCs from dried blood spots. The PCBs and OCs were quantified in whole marine mammal blood spotted on Whatman Protein Saver cards (PSCs) by extracting the analytes into acetonitrile acidified with formic acid, followed by GC-MS/MS analysis. The samples were analyzed in positive electron impact (EI+) ionization mode with the electron energy set to 40?eV to preserve analyte integrity. Fortified blood with the analytes of interest was used for method validation and subsequent sample screening. The recoveries of targeted analytes ranged from 62.5% to 107.8%, with relative standard deviations ranging from 0.09% to 4.6% at a 100?ng·mL^?1 concentration level. The method detection limits were from 40.4?ng·g^?1 to 179.2?ng·g^?1 for the PCBs and 37.6?ng·g^?1 to 145.1?ng·g^?1 for the OCs. The use of dried blood spots provided for numerous advantages compared to whole blood samples while demonstrating reduced matrix effects and enhanced sample lifespan while retaining analyte sensitivity.     

Synthesis of a graphene‐based nanocomposite for the dispersive solid‐phase extraction of vancomycin from biological samples

The approach of this work was to study the capability of graphene‐based materials in the field of biological sample preparation. A polypyrrole/graphene composite was synthesized and characterized. The potential of the nanocomposite was investigated as a sorbent in dispersive solid‐phase extraction followed by high‐performance liquid chromatography with UV detection for vancomycin as a model drug. The effect of different parameters influencing extraction efficiency such as sample pH and sample volume, ionic strength, extraction time, type, and volume of desorption solvent and desorption time were investigated. A comparison study was also conducted between polypyrrole/graphene and some different novel and classic sorbents. Under optimized conditions, the calibration curve for vancomycin showed linearity in the range of 0.05–10 μg/mL. In addition, limits of detection, and quantification were 0.003 and 0.01 μg/mL, respectively. The intraday and interday relative standard deviations at a concentration of 0.05 μg/mL (n = 3) were 1.6 and 2.1%, respectively. Furthermore, the proposed method was successfully applied for the determination of vancomycin in plasma and urine samples. The relative recoveries indicated the feasibility of graphene‐based sorbents in biological sample analysis.     

Preparation of polypyrrole‐graft‐poly(N‐isopropylacrylamide)/silver nanocomposites from pyrrolyl‐capped macromonomer by AgNO3 and their stimuli responsibility of light emission

Pyrrolyl‐capped poly(N‐isopropylacrylamide) macromonomers (Py‐PNIPAM) were prepared through reversible addition‐fragmentation‐transfer polymerization with benzyl 1‐pyrrolylcarbodithioate as chain‐transfer agent. Polymerizations of Py‐PNIPAM with/without pyrrole using AgNO₃ as oxidizing agent and dimethylforamide as solvent resulted in graft copolymers of polypyrrole‐graft‐poly(N‐isopropylacrylamide) (PPy‐g‐PNIPAM) as well as silver nanoparticles, leading to the formation of PPy‐g‐PNIPAM/silver nanocomposites. The resulting nanocomposites were soluble in water when the content of PPy was low, and when the molar ratio of Py/Py‐PNIPAM increased to 30, the resulting products became insoluble in water. The resulting nanocomposites had special optical properties because of PPy as well as the temperature‐responsible PNIPAM. The chemical structure and composition of nanocomposite were characterized by ¹H nuclear magnetic resonance spectroscopy, gel permeation chromatograms, fourier transform infrared spectroscopy, and X‐ray diffraction. Their optical properties were characterized by UV–vis and fluorescence spectroscopy. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6950–6960, 2008     

Combination of Solid‐Phase Micro‐Extraction and Direct Analysis in Real Time‐Fourier Transform Ion Cyclotron Resonance Mass Spectrometry for Sensitive and Rapid Analysis of 15 Phthalate Plasticizers in Beverages

A method for rapid identification and quantification of phthalate plasticizers in beverages was developed. A number of 15 phthalate plasticizers which covered all the phthalates concerned in the US Consumer Product Safety Improvement Act (CPSIA), European Union legislations and Chinese national standards (GB) were analyzed. By a combined solid‐phase micro‐extraction (SPME) and direct analysis in real time mass spectrometry (DART‐MS) approach, phthalates at sub‐ng·mL^?1 levels can be qualitatively and quantitatively analyzed in a short time. The use of ultrahigh‐resolving power and the accurate mass measurement capacity naturally provided by Fourier transform ion cyclotron resonance mass spectrometry (FT‐ICR‐MS) minimizes the matrix interferences and thus enables the evaluation of phthalates in a complex matrix without extensive sample handlings or preparations. The limits of quantification (LOQs) were estimated to be at 0.3–5.0 ng·mL^?1, lower than the Maximum Residue Limit (MRL) regulated by the European Union legislations (2007/19/EC) in foods, beverages, food packaging and toys (0.3–30 ng·mL^?1). This rapid and easy‐to‐use SPME‐DART‐FT‐ICR‐MS method provided a relatively high‐throughput and powerful analytical approach for quick testing and screening phthalates in beverages and water samples to ensure food safety.     

Synthesis and evaluation of dummy molecularly imprinted microspheres for the specific solid‐phase extraction of six anthraquinones from slimming tea

Dummy molecularly imprinted microspheres with danthron as template were synthesized and their performance was evaluated. Accelerated solvent extraction can rapidly and effectively remove template molecules from the microspheres. The microspheres were applied as a specific sorbent for solid‐phase extraction of six anthraquinones from slimming tea, showing excellent affinity and high selectivity to danthron and the target analytes. The molecular recognition mechanisms were discussed by the experimental validation with IR spectroscopy. The sample was treated using accelerated solvent extraction followed by dummy molecularly imprinted microspheres solid‐phase extraction. Under the optimized ultra high performance liquid chromatographic conditions, the six target analytes can be baseline separated in 8 min, and good linearity was obtained in a range of 0.1–40 μg/mL with the correlation coefficient (r²) of ≥0.9998. The method limit of quantification was in a range of 1–2 mg/kg, it can ensure analysis of anthraquinones at mg/kg level. The intra‐ and interday precision (RSD, n = 6) for the analysis of the six analytes in a slimming tea was less than 4.5 and 5.4%, respectively. The developed method can be applied for the selective extraction, effective separation, and rapid determination of six anthraquinones in slimming tea.     

Quantitative determination of trace phenazopyridine in human urine samples by hyphenation of dispersive solid‐phase extraction and liquid‐phase microextraction followed by gas chromatography/mass spectrometry analysis

Magnetic dispersive solid‐phase extraction followed by dispersive liquid?liquid microextraction coupled with gas chromatography/mass spectrometry was applied for the quantitative analysis of phenazopyridine in urinary samples. Magnetic dispersive solid‐phase extraction was carried out using magnetic graphene oxide nanoparticles modified by poly(thiophene‐pyrrole) copolymer. The eluting solvent of this step was used as the disperser solvent for the dispersive liquid?liquid microextraction procedure. To reach the maximum efficiency of the method, effective parameters including sorbent amount, adsorption time, type and volume of disperser and extraction solvents, pH of the sample solution, and ionic strength as well as desorption time, and approach were optimized, separately. Characterization of the synthesized sorbent was studied by utilizing infrared spectroscopy, scanning electron microscopy, and energy‐dispersive X‐ray analysis. Calibration curve was linear in the range of 0.5?250 ng/mL (R² = 0.9988) with limits of detection and quantification of 0.1 and 0.5 ng/mL, respectively. Intra‐ and interday precisions (RSD%, n = 3) of the method were in the range of 4.6?5.4% and 4.0?5.5%, respectively, at three different concentration levels. Under the optimal condition, this method was successfully applied for the determination of phenazopyridine in human urine samples. The relative recoveries were obtained in the range of 85.0?89.0%.     

Evaluation of the Conductivity of the Polypyrrole Film via Its CC Bonds Stretching on Surface‐Enhanced Raman Spectrum

In this study, the conductivities of various polypyrrole (PPy) films were evaluated via the corresponding surface‐enhanced Raman scattering (SERS) spectrum and X‐ray photoelectron spectroscopy (XPS). The results indicate that the peak position of C?C bonds stretching of PPy obtained from the SERS spectrum shows more exactly both qualitatively and quantitatively representing the conductivity of PPy than the N⁺/N ratio or the doping level obtained from the XPS analysis does. Namely the peak position of C?C bonds stretching of PPy monotone decreases to a lower frequency side with the increase of the conductivity of PPy. Furthermore, a satisfactory correlated equation between them was obtained. On the contrary, neither the N⁺/N ratio nor the doping level can be qualitatively reflective on the corresponding conductivity of PPy.