Long-term external quality assessment program for CD4+ T-lymphocyte enumeration in Thailand

The accuracy and reliability of CD4+ T-lymphocyte enumeration are crucial for HIV healthcare management. Thailand’s CD4 external quality assessment (EQA) program was implemented in 2003. This program aims to improve the quality of CD4 testing by providing the quality control material, remedial action, and technical training. In this article, the overall longitudinal performance of the participating laboratories from 2003 to 2015 is reported. The EQA blood samples were sent to the participating laboratories in Thailand and other Southeast Asian (SEA) countries. The participants were requested to enumerate CD3+ and CD4+ T-lymphocytes. The trimmed mean, standard deviation (SD), coefficient of variation (CV), and standard deviation index (SDI) of both fraction and number were calculated from the returned data. Our result indicated a continuously increasing number of participants. The response rate of 72 trials was 98 %. The outlier rates for the fraction and number of CD4+ T-lymphocytes were 3.3 % and 3.4 %, respectively. The average CV of the fraction and number of CD4+ T-lymphocytes was 7.1 % and 9.4 %, respectively. In addition, the analysis of our current EQA trial no. 072 revealed that more than 98 % of participating laboratories had SDI values between ?2 and +2 for both fraction and number of CD3+ and CD4+ T-lymphocytes. In conclusion, the implementation of the CD4 EQA program in Thailand and other SEA countries has led to a reduction in the variability of the results of the CD4 count between laboratories and a continuous improvement in laboratory performance.     

Application of ISO 13528 robust statistical method for external quality assessment of blood glucose measurements in China

External quality assessment (EQA) including extensive participants often result in abnormal distribution. Robust statistical methods are insensitive to slight deviation for a given probability model and can estimate the population parameters utilizing robust algorithm. The aim of this study was to evaluate the blood glucose testing performance of EQA in China using ISO 13528 robust statistical method. A total of 4571 participants measured two lots of materials at different concentrations and submitted the results through the Clinet-EQA reporting system V1.5. Data were collected and analyzed by Clinet-EQA evaluating system and SPSS 13.0. Participants were classified by method principles they adopted. Acceptability of relative differences between each result and robust mean of the group was calculated using biological variation desirable quality specification for allowable total error. The kernel density plots and Youden Plot were also applied to show the distribution of z-scores. The robust means of the two lots were 6.31 mmol/L and 15.71 mmol/L, and the robust standard deviations were 0.23 mmol/L and 0.5 mmol/L, respectively. Acceptability of relative differences was more than 90 % among all groups. About 91.5% and 89.7 % of the participants out of the two lots fulfilled the condition of |z| ≤ 2. In addition, 87.2 % participants fell inside the confidence ellipse for probability levels of 95 % in Youden Plot. According to the statistical results, we can conclude that most participants are qualified for performing blood glucose test and ISO 13528 robust statistical method is appropriate for EQA result analysis.     

A fluorogenic heterogeneous immunoassay for cardiac muscle troponin cTnI on a digital microfluidic device

We describe a fluorogenic two-site noncompetitive heterogeneous immunoassay with magnetic beads on a low-voltage digital microfluidic platform using closed electrowetting-on-dielectric (EWOD). All the steps of an enzyme-linked immunosorbent assay (ELISA) were performed on the device using 9H-(1, 3-dichloro-9, 9-dimethylacridin-2-one-7-yl) phosphate as the fluorogenic substrate for the enzyme alkaline phosphatase. The performance of the system was demonstrated with cardiac marker Troponin I (cTnI) as a model analyte in phosphate-buffered saline samples. cTnI was detected within the diagnostically relevant range with a limit of detection of 2.0 ng/mL (CV?=?6.47 %). Washing of magnetic beads was achieved by movement through a narrow region of buffer bridging one drop to another with minimal fluid transfer. More than 90 % of the unbound reagents were removed after five washes. Further experiments testing human blood serum on the same platform demonstrated a sample-to-answer time at ～18.5 min detecting 6.79 ng/mL cTnI.     

Utilization of low-cost sorbent for removal and separation of 134Cs, 60Co and 152+154Eu radionuclides from aqueous solution

Eggshell material was used as low-cost and eco-friendly biosorbent for removal of ¹³⁴Cs, ⁶⁰Co and ^152+154Eu radionuclides from aqueous solution. The eggshell material was calcined at 500 and 800 °C, and then characterized. Comparative studies on the natural and calcined eggshell for sorption of the three radionuclides were carried out. It was found that, the uptake is in the order: Eu(III) > Co(II) > Cs(I). Further, column chromatography was used in separation of ¹³⁴Cs, ⁶⁰Co and ^152+154Eu using 0.15, 0.2 and 0.5 mol/l nitric acid, respectively. Eggshell material can be considered as a promising material for separation of radionuclides from radioactive waste solution.     

An experimental and theoretical study on the structure and photoactivity of XFe2O4 (X = Mn,Fe, Ni,Co, and Zn) structures

XFe₂O₄ magnetic nanoparticles (X = Mn, Fe, Co, Ni, and Zn) were prepared by using two methods: coprecipitation and hydrothermal. The synthesized nanoparticles were compared according to the separation in an external magnetic field and finally, the hydrothermal method was specified as a better synthesis method. The magnetic nanoparticles were characterized by physico-chemical analysis methods such as Vibrating Sample Magnetometer (VSM), X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), nitrogen adsorption-adsorption isotherm and Transmission Electron Microscopy (TEM). Magnetic properties of synthesized nanoparticles were studied by ab-initio theoretical methods to confirm and compare with the experimental results. According to the VSM analysis, all of magnetic nanoparticles had good magnetization while CoFe₂O₄ nanoparticles showed the ferromagnetic behavior. The magnetic properties of XFe₂O₄ configurations were studied using Density Functional Theory ab-initio method. The theoretical results were consistent with experimental magnetizations in the absence of external field. Finally, the photocatalytic behavior of prepared samples was investigated in the presence of oxone as an accelerated agent for degradation of an azo dye.     

Synthesis and optical properties of BaTiO3:Eu3+@SiO2 glass ceramic nano particles

BaTiO₃:(5 %)Eu³⁺ nanoparticles and BaTiO₃:(5 %)Eu³⁺@SiO₂ composites were synthesized by the solvothermal method. The effects on the structure, morphology and luminescent properties were studied using samples with different molar ratios of BaTiO₃:(5 %)Eu³⁺@SiO₂: 60:40, 50:50, 40:60, 30:70, 20:80, 10:90, 08:92, 6.5:93.5, 05:95, and 1.5:98.5. When the amount of silica in the composites was increased, the orange emission of Eu³⁺ increased, too; this was observed by exciting the charge transfer band centered at 283 nm. Furthermore, an increase in the intensity of the emission was obtained under excitation at 394 nm as a consequence of the improvement in the crystallinity of the samples. The presence of silica and the degree of crystallinity of the samples were determined through the Fourier transform infrared spectra and X-ray diffraction patterns. All of the results suggest that our ceramic material could be a good candidate for biomedical applications such as biolabeling, since the luminescence of BaTiO₃:(5 %)Eu³⁺@SiO₂ composites have an emission intensity higher than that of nanoparticles composed solely of BaTiO₃:Eu³⁺. This work demonstrates that BaTiO₃:Eu³⁺@SiO₂ composites have an emission intensity higher than that of nanoparticles composed solely of BaTiO₃:Eu³⁺.     

Ion beam irradiation of ZnS dispersed in PMMA and its photocatalytic application

ZnS nanoparticles implanted with 45 keV O⁵⁺ ion beam exhibited 83.6 % degradation of methyl blue in 2 h. This idea was utilized to fabricate nanocomposite system of ZnS and PMMA where ZnS nanoparticles were immobilized in PMMA film and irradiated with 45 keV O⁵⁺ ion beam at particle fluence of 2.5 × 10¹⁵, 1 × 10¹⁶ and 4 × 10¹⁶ particles/cm². These irradiated batches of ZnS nanoparticle immobilized in PMMA batches revealed formation of porous structure characterized by scanning electron microscopy and these batches exhibited 54 % photocatalytic degradation of methyl blue in 80 min which was higher as compared to the pristine ZnS nanoparticles.     

Magnetic molecularly imprinted polymer nanoparticles for the solid-phase extraction of paracetamol from plasma samples,followed its determination by HPLC

We are presenting magnetic molecularly imprinted polymer nanoparticles (m-MIPs) for solid-phase extraction and sample clean-up of paracetamol. The m-MIPs were prepared from magnetite (Fe₃O₄) as the magnetic component, paracetamol as the template, methacrylic acid as a functional monomer, and 2-(methacrylamido) ethyl methacrylate as a cross-linker. The m-MIPs were then characterized by transmission electron microscopy, FT-IR spectroscopy, X-ray diffraction and vibrating sample magnetometry. The m-MIPs were applied to the extraction of paracetamol from human blood plasma samples. Following its elution from the column loaded with the m-MIPs with an acetonitrile-buffer (9:1) mixture, it was submitted to HPLC analysis. Paracetamol can be quantified by this method in the 1 μg L^?1 to 300 μg L^?1 concentration range. The limit of detection and limit of quantification in plasma samples are 0.17 and 0.4 μg L^?1. The preconcentration factor of the m-MIPs is 40. The HPLC method shows good precision (4.5 % at 50 μg L^?1 levels) and recoveries (between 83 and 91 %) from spiked plasma samples. Figure

We are presenting magnetic molecularly imprinted polymer nanoparticles (m-MIPs) for solid-phase extraction and sample clean-up of paracetamol. The m-MIPs were applied to the extraction of paracetamol from human blood plasma samples     

Characterisation and comparison of biomass ashes with different thermal histories using TG-DSC

The present research is focused on the characterisation and comparison of biomass ashes from wood pellet with different thermal histories. One of the ashes is obtained in a muffle furnace until its mass stabilization reaching a temperature of 550 °C, low temperature ash (LTA); the other one came from an experimental fixed bed combustor after 4 h of stable combustion in which the temperature reached is above 1,000 °C, high temperature ash (HTA). The samples were studied using Thermogravimetry and Differential Scanning Calorimetry (TG-DSC) techniques, and they were subjected to a heating up to 900 °C under an inert atmosphere with the objective of perceiving the differences in their thermal behaviour. At these temperatures, complex phase transformations occur, related to decomposition of carbonates and formation of silicates. TG and DSC curves are compared and some differences in mass loss, temperature peaks and enthalpy associated to endothermic effects are detected and they are explained based on the different compositions of both samples obtained at different temperatures. Other techniques were applied for the determination of the chemical composition of the ashes; X-ray fluorescence and Scanning electron microscopy with energy dispersive X-ray spectroscopy showed the elements present in the ashes, and X-ray diffraction revealed the crystalline phases and confirms that LTA is mainly composed of carbonates, while HTA mostly consists of silicates.     

Co3O4/SiO2 nanocomposites for supercapacitor application

In this study, Co₃O₄/SiO₂ nanocomposites have been successfully synthesized by citrate–gel method by utilizing SiO₂ matrix for Co₃O₄ embedment. Spectroscopy analyses confirm the formation of high crystalline Co₃O₄ nanoparticles; meanwhile, microscopy findings reveal that the Co₃O₄ nanoparticles are embedded in SiO₂ matrix. Electrochemical properties of the Co₃O₄/SiO₂ nanocomposites were carried out using cyclic voltammetry (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS) in 5 M KOH electrolyte. The findings show that the charge storage of Co₃O₄/SiO₂ nanocomposites is mainly due to the reversible redox reaction (pseudocapacitance). The highest specific capacitance of 1,143 F g ^?1 could be achieved at a scan rate of 2.5 mV s^?1 in the potential region between 0 and 0.6 V. Furthermore, high-capacitance retention (>92 %) after 900 continuous charge–discharge tests reveals the excellent stability of the nanocomposites. It is worth noting from the EIS measurements that the nanocomposites have low ESR value of 0.33 Ω. The results manifest that Co₃O₄/SiO₂ nanocomposites are the promising electrode material for supercapacitor application.     

Simultaneous sensing of L-tyrosine and epinephrine using a glassy carbon electrode modified with nafion and CeO2 nanoparticles

An electrochemical sensor was developed and tested for detection of L-tyrosine in the presence of epinephrine by surface modification of a glassy carbon electrode (GCE) with Nafion and cerium dioxide nanoparticles. Fabrication parameters of a surfactant-assisted precipitation method were optimized to produce 2–3 nm CeO₂ nanoparticles with very high surface-to-volume ratio. The resulting nanocrystals were characterized structurally and morphologically by X-ray diffractometery (XRD), scanning and high resolution transmission electron microscopy (SEM and HR-TEM). The nanopowder is sonochemically dispersed in a Nafion solution which is then used to modify the surface of a GCE electrode. The electrochemical activity of L-tyrosine and epinephrine was investigated using both a Nafion-CeO₂ coated and a bare GCE. The modified electrode exhibits a significant electrochemical oxidation effect of L-tyrosine in a 0.2 M Britton-Robinson (B-R) buffer solution of pH 2. The electro-oxidation peak current increases linearly with the L-tyrosine concentration in the molar concentration range of 2 to 160 μM. By employing differential pulse voltammetry (DPV) for simultaneous measurements, we detected two reproducible peaks for L-tyrosine and epinephrine in the same solution with a peak separation of about 443 mV. The detection limit of the sensor (signal to noise ratio of 3) for L-tyrosine is ~90 nM and the sensitivity is 0.20 μA μM^?1, while for epinephrine these values are ~60 nM and 0.19 μA μM^?1. The sensor exhibited excellent selectivity, sensitivity, reproducibility and stability as well as a very good recovery time in real human blood serum samples.

Simultaneous electrochemical determination of L-tyrosine and epinephrine in blood plasma with Nafion-CeO₂/GCE modified electrode showing a 443 mV peak-to-peak potential difference between species oxidation peak currents.     

Novel worm-like amphiphilic micelles of folate-targeted cyclodextrin/retinoic acid for delivery of doxorubicin in KG-1 cells

Folate-targeted cyclodextrin/retinoic acid (CD/RA) conjugate was synthesized using carbonyldiimidazole (CDI) and dimethylaminopyridine (DMAP). The structure of the produced macromolecule was studied by FTIR and ¹HNMR. The developed macromolecule could self-aggregate to form micelles. Critical micelle concentration (CMC) of the macromolecule was determined by pyrene as a fluorescent probe. Doxorubicin (DOX)-loaded micelles were prepared by direct dissolution method. To optimize the effect of cyclodextrin type (α or β), the molar ratio of RA to CD and the drug content, a full factorial design was used and their effects on particle size, polydispersity index, zeta potential, loading efficiency (LE%), and release efficiency (RE₂₄%) in 24 h were studied. Orientation of folate ligand on the surface of the micelles was studied by X-ray photoelectron spectroscopy (XPS) technique. The cytotoxicity of DOX-loaded micelles was studied on KG-1 cells which overexpressed folate receptor (FR) and FR-negative HepG2 cells using MTT assay. FTIR and ¹HNMR spectra confirmed successful production of the micelles and XPS spectra showed surface orientation of folate. The best results obtained from β-cyclodextrin with molar ratio of 4 to RA and 15 % drug content. The optimized micelles showed the particle size of 103?±?4 nm, zeta potential of ?36 mV, polydispersity index of 0.28?±?0.05, LE% of 100 %, and RE₂₄% of 69.88?±?1.6 %. The IC₅₀ of targeted micelles was half of non-targeted micelles and free DOX.     

Nano-LC-MS/MS for the quantitation of prostanoids in immune cells

Prostanoids, derivatives of arachidonic acid, are involved in inflammation and immune reactions. To understand the role of prostanoids produced by diverse immune cells, a highly sensitive quantitation method for prostaglandin E₂ (PGE₂), prostaglandin D₂ (PGD₂), 6-keto prostaglandin F_1α (6-keto PGF_1α), prostaglandin F_2α (PGF_2α), and thromboxane B₂ (TXB₂) by means of nano-liquid chromatography-tandem mass spectrometry has been developed. It was validated according to the guidelines of the Food and Drug Administration (FDA) in terms of linearity, precision, accuracy, recovery, stability, and lower limit of quantitation (LLOQ). The LLOQ were 25 pg/mL in the injected solution (75 fg on column (o.c.)) for PGE₂ and PGD₂ and 37.5 pg/mL (112.5 fg on column) for 6-keto PGF_1α, PGF_2α, and TXB₂, respectively. It was successfully applied to murine mast cells isolated from paws after zymosan injection and to CD4⁺ and CD8⁺ T lymphocytes from blood of sensitized versus non-sensitized mice in context of a delayed type hypersensitivity model. About 5,000 (T cells) to 40,000 (mast cells) cells were sufficient for quantitation. In the mast cells, the production of PGE₂ increased at a significantly higher extent than the synthesis of the other prostanoids. The T lymphocytes did not show any difference in prostanoid production, no matter whether they were obtained from sensitized mice or non-sensitized mice.     

Potassium-based algorithm allows correction for the hematocrit bias in quantitative analysis of caffeine and its major metabolite in dried blood spots

Although dried blood spot (DBS) sampling is increasingly receiving interest as a potential alternative to traditional blood sampling, the impact of hematocrit (Hct) on DBS results is limiting its final breakthrough in routine bioanalysis. To predict the Hct of a given DBS, potassium (K⁺) proved to be a reliable marker. The aim of this study was to evaluate whether application of an algorithm, based upon predicted Hct or K⁺ concentrations as such, allowed correction for the Hct bias. Using validated LC-MS/MS methods, caffeine, chosen as a model compound, was determined in whole blood and corresponding DBS samples with a broad Hct range (0.18–0.47). A reference subset (n?=?50) was used to generate an algorithm based on K⁺ concentrations in DBS. Application of the developed algorithm on an independent test set (n?=?50) alleviated the assay bias, especially at lower Hct values. Before correction, differences between DBS and whole blood concentrations ranged from ?29.1 to 21.1 %. The mean difference, as obtained by Bland-Altman comparison, was ?6.6 % (95 % confidence interval (CI), ?9.7 to ?3.4 %). After application of the algorithm, differences between corrected and whole blood concentrations lay between ?19.9 and 13.9 % with a mean difference of ?2.1 % (95 % CI, ?4.5 to 0.3 %). The same algorithm was applied to a separate compound, paraxanthine, which was determined in 103 samples (Hct range, 0.17–0.47), yielding similar results. In conclusion, a K⁺-based algorithm allows correction for the Hct bias in the quantitative analysis of caffeine and its metabolite paraxanthine. Graphical Abstract

Percentage differences between uncorrected DBS and whole blood paraxanthine concentrations (upper panel) and between corrected and whole blood paraxanthine concentrations (lower panel) (n = 103)     

Determination of methylisothiocyanate in soil and water by HS-SPME followed by GC–MS–MS with a triple quadrupole

Methylisothiocyanate (MITC) is the main degradation product of metam sodium, a soil disinfectant widely used in agriculture, and is responsible for its disinfectant properties. Because MITC is highly toxic and volatile, metam sodium has to be applied in a manner that tries to reduce atmospheric emissions but still maintains adequate concentration of MITC in soil to ensure its disinfectant effect. Thus, monitoring of MITC concentrations in soil is required, and to this end sensitive, fast, and reliable analytical methods must be developed. In this work, a headspace solid-phase microextraction (HS-SPME) method was developed for MITC determination in water and soil samples using gas chromatography-tandem mass spectrometry (GC–MS–MS) with a triple-quadrupole analyzer. Two MS–MS transitions were acquired to ensure the reliable quantification and confirmation of the analyte. The method had linear behavior in the range tested (0.026–2.6 ng mL^?1 in water, 1–100 ng g^?1 in soil) with r ² over 0.999. Detection limits were 0.017 ng mL^?1 and 0.1 ng g^?1 in water and soil, respectively. Recoveries for five replicates were in the range 76–92 %, and RSD was below 7 % at the two spiking levels tested for each matrix (0.1 and 1 ng mL^?1 for water, 4 and 40 ng g^?1 for soil). The potential of using multiple HS-SPME for analyzing soil samples was also investigated, and its feasibility for quantification of MITC evaluated. The developed HS-SPME method was applied to soil samples from experimental plots treated with metam sodium following good agriculture practices. Figure

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Chitosan-poly(m-phenylenediamine)@Fe3O4 nanocomposite for magnetic solid-phase extraction of polychlorinated biphenyls from water samples

A extraction medium based on chitosan-poly(m-phenylenediamine) (CS-PPD) @Fe₃O₄ nanocomposite was synthesized by chemical polymerization of m-phenylenediamine in the presence of chitosan coated magnetic nanocomposite, and for the first time, used as the sorbent for the magnetic solid-phase extraction (MSPE) of seven polychlorinated biphenyls (PCB28, PCB52, PCB101, PCB118, PCB138, PCB153, and PCB180) at trace levels in water samples. Gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) was used for PCBs quantification and detection. Several factors related to MSPE efficiencies, such as type and amount of sorbent, extraction time, sample pH, and desorption conditions were investigated. Under the optimized conditions, an excellent linearity was observed in the range of 1.0–200 ng L^–1 for PCB180, 0.5–200 ng L^–1 for the other six PCBs with the correlation coefficients ranging from 0.9954 to 0.9993. The good recoveries at spiked levels of 10.0, 20.0, and 50.0 ng L^–1 were obtained in the range of 94 %–108 %, and the coefficients of variations were less than 6 %. The proposed method was feasible, rapid, and easy to operate for the trace analysis of the PCBs in local aquaculture water, livestock breeding water, and sewage water samples. Graphical Abstract

Fig. 1 Schematic diagram for the preparation of chitosan–poly(m-phenylenediamine) @Fe₃O₄ nanocomposite.     

Phase-optimized chip-based liquid chromatography

In this contribution we introduce phase-optimized columns for highly efficient liquid chromatographic separations in microfluidic glass chips. In phase-optimized liquid chromatography the selectivity and geometry of the stationary phase are precisely adjusted to provide an optimal separation of a mixture of interest. The separation of nine polycyclic aromatic hydrocarbons under reversed-phase conditions was investigated. Standard HPLC was utilized to explore the retention parameters of each analyte on a set of five commercially available stationary phases. From these experiments the properties of an optimal on-chip column were calculated assuming a zero-void-volume performance for the chip chromatography. A phase-optimized on-chip column only 30 mm long provided baseline resolution of all signals within 4 min. The separation performance of a chip column comprising various stationary phases can be precisely predicted by a set of traditional HPLC experiments. The approach has great potential for the directed development of tailor-made chromatography chips for specific applications.     

Self-assembled fabrication and flame-retardant properties of reduced graphene oxide/waterborne polyurethane nanocomposites

The graphite oxide (GO) was prepared from expandable graphite by the pressurized oxidation method, and samples were characterized using XRD, UV–Vis, and TEM. GO is reduced in situ emulsion using hydrazine to achieve reduced graphene oxide/waterborne polyurethane (rGO/WPU) nanocomposites. The effect of rGO content on the stability, fracture morphologies, mechanical performance, thermal degradation, and flame-retardant properties of rGO/WPU composites was investigated by zeta potential analyzer, TEM, SEM, universal testing machine, TG, and Cone Calorimeter. The results of zeta potential, TEM, and SEM analysis indicate that rGO has a good stability and dispersibility in rGO/WPU nanocomposites. The results of mechanical tests showed that the mechanical properties of rGO/WPU nanocomposites increased consistently with increasing rGO content up to 2 mass%, and TG showed that the thermostability of rGO/WPU nanocomposites decreased slightly compared to pure WPU, but carbon residue increased from 0.99 to 1.99 % when the mass fraction of rGO in WPU is 2 %. Cone Calorimeter test indicated that the flame-retardant and smoke suppression properties of rGO/WPU composites showed significant improvement compared to the WPU alone. When the mass fraction of rGO is 1 %, the total smoke release and smoke factor decreased by 25 and 38 %, respectively, compared to those of pure WPU.     

Electroentrapment of Polyaniline in [3-(2,3-Epoxypropoxy)propyl]trimethoxysilane-Derived Xerogel: A Facile Methodology Towards Molecularly Imprinted Xerogels

A novel polyaniline (PANI)/silica hybrid composite, as a selective coating, was synthesized by the simultaneous sol–gel process and in situ electro-polymerization of aniline and employed for imprinting naproxen. The synthesized composite was chemically bonded inside a copper tube for online capillary microextraction (CME) in combination with high-performance liquid chromatography (HPLC). The copper tube was intended for use as an unbreakable substrate for CME and the HPLC injection loop. Four copper tubes containing different coatings were prepared accordingly to achieve the most appropriate extracting medium for naproxen. Coating 1 was a xerogel of [3-(2,3-epoxypropoxy)propyl]trimethoxysilane (EPPTMOS) synthesized by sol–gel technology and PANI as a conductive polymer (CP) was electrochemically prepared as coating 2. Coating 3 (sol–gel–CP) included the electroentrapped PANI into the xerogel of EPPTMOS, representing the non-imprinted xerogel (NIX) and coating 4, the molecularly imprinted xerogel (MIX), contained entrapped PANI into the xerogel of EPPTMOS, while naproxen template was already imprinted into the composite structure. Extraction efficiency of MIX towards naproxen was about 4–30 times greater than the others. Electroentrapped PANI into the silica xerogel might be responsible for the enhanced extraction efficiency, originating from high surface area of PANI as well as its role in π–π interactions. The mild conditions used in this process enabled the incorporation of organic species such as PANI into the silica particles without degradation. The main advantage of addition of PANI during the sol–gel process was the reduction of gelation time from more than a week to a few hours and, therefore, achieving a facile and controllable method for preparation of selective media. Furosemide, clodinafop-propargyl and haloxyfop-etotyl were also selected to investigate selectivity of the prepared MIX towards naproxen. Ratio of MIX/NIX, a criterion of selectivity, was 3.8, 1.1, 1.2, and 1.4 for naproxen, clodinafop, haloxyfop and furosemide, respectively. The linearity of the HPLC method for naproxen was in the range of 10–1,000 µg L^?1. The limit of detection value was found to be 5 µg L^?1 and RSD % of 2.9 (n = 5) was obtained. Real samples such as blood plasma and urine species were analyzed by the developed method and the relative recovery percentages of 76 and 94 % were obtained for the spiked samples.     

Hexafluoroisopropanol-induced coacervation in aqueous mixed systems of cationic and anionic surfactants for the extraction of sulfonamides in water samples

Hexafluoroisopropanol (HFIP)-induced coacervation in aqueous mixed systems of catanionic surfactants of dodecyltrimethylammonium bromide (DTAB) and sodium dodecyl sulfate (SDS) was described in detail, and its application in the extraction of strongly polar sulfonamides (SAs) was investigated. With 10 % (v/v) HFIP inclusion, coacervation formation and two-phase separation occur in a wide range of SDS/DTAB mole ratios (88:12～0:100 mol/mol) and total surfactant concentrations (10～200 mmol/L). The interactions between HFIP and DTAB play an important role in coacervation formation. The HFIP-induced SDS–DTAB coacervation extraction proves to be an efficient method for the extraction and preconcentration of SAs. Both hydrophobic interaction and polar interactions (hydrogen–bond, electrostatic, and π-cation) contribute to the distribution of SAs into coacervate phase. The proposed HFIP-induced SDS–DTAB coacervation extraction combined with HPLC–UV was employed for the extraction and quantitative determination of SAs in environmental water samples. Limits of detection were 1.4～2.5 ng mL^?1. Excellent linearity with correlation coefficients from 0.9990 to 0.9995 was obtained in the concentration of 0.01～10 μg mL^?1. Relative recoveries were in the range of 93.4～105.9 % for analysis of the lake, underground, and tap water samples spiked with SAs at 0.01, 1.0, and 10 μg/mL, respectively. Relative standard deviations were 0.7～3.2 % for intraday precision and 1.3～4.6 % for interday precision (n?=?3). Concentration factors were 17～49 for three water samples spiked with 0.01 μg/mL SAs. The results demonstrate that the proposed extraction method is feasible for the preconcentration and determination of trace SAs in real water samples. Graphical abstract

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