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papers from the latest issue:
Selective determination of gold(III) ion using CuO microsheets as a solid phase adsorbent prior to ICP-OES measurements
20 November 2012,
09:27:36
Publication year:
2012
Source:Talanta
Mohammed M. Rahman, Sher Bahadar Khan, Hadi M. Marwani, Abdullah M. Asiri, Khalid A. Alamry, Abdulrahman O. Al-Youbi
We have prepared calcined CuO microsheets (MSs) by a wet-chemical process using reducing agents in alkaline medium and characterized by UV/vis., Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD), and field-emission scanning electron microscopy (FESEM) etc. The detailed structural, compositional, and optical characterizations of the MSs were evaluated by XRD pattern, FT-IR, X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy, respectively which confirmed that the obtained MSs are well-crystalline CuO and possessed good optical properties. The CuO MSs morphology was investigated by FESEM, which confirmed that the calcined nanomaterials were sheet-shaped and growth in large-quantity. Here, the efficiency of the CuO MS was applied for a selective adsorption of gold(III) ion prior to its detection by inductively coupled plasma-optical emission spectrometry (ICP-OES). The selectivity of CuO MSs towards various metal ions, including Au(III), Cd(II), Co(II), Cr(III), Fe(III), Pd(II), and Zn(II) was analyzed. Based on the adsorption isotherm study, it was confirmed that the selectivity of MSs phase was the most towards Au(III) ion. The static adsorption capacity for Au(III) was calculated to be 57.0mgg−1. From Langmuir adsorption isotherm, it was confirm that the adsorption process was mainly monolayer-adsorption onto a surface containing a finite number of adsorption sites.
Source:Talanta
Mohammed M. Rahman, Sher Bahadar Khan, Hadi M. Marwani, Abdullah M. Asiri, Khalid A. Alamry, Abdulrahman O. Al-Youbi
We have prepared calcined CuO microsheets (MSs) by a wet-chemical process using reducing agents in alkaline medium and characterized by UV/vis., Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD), and field-emission scanning electron microscopy (FESEM) etc. The detailed structural, compositional, and optical characterizations of the MSs were evaluated by XRD pattern, FT-IR, X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy, respectively which confirmed that the obtained MSs are well-crystalline CuO and possessed good optical properties. The CuO MSs morphology was investigated by FESEM, which confirmed that the calcined nanomaterials were sheet-shaped and growth in large-quantity. Here, the efficiency of the CuO MS was applied for a selective adsorption of gold(III) ion prior to its detection by inductively coupled plasma-optical emission spectrometry (ICP-OES). The selectivity of CuO MSs towards various metal ions, including Au(III), Cd(II), Co(II), Cr(III), Fe(III), Pd(II), and Zn(II) was analyzed. Based on the adsorption isotherm study, it was confirmed that the selectivity of MSs phase was the most towards Au(III) ion. The static adsorption capacity for Au(III) was calculated to be 57.0mgg−1. From Langmuir adsorption isotherm, it was confirm that the adsorption process was mainly monolayer-adsorption onto a surface containing a finite number of adsorption sites.
Highlights
► Selective detection of Gold(III) Ion based on un-doped CuO Microsheets. ► CuO Microsheets used as a Selective Solid Phase Adsorbent. ► The static adsorption capacity for Au(III) was calculated to be 57.0mgg−1. ► Adsorption process was mainly monolayer based onto a surface containing a finite number of adsorption sitesDetermination of amino acids by capillary electrophoresis with differential resonant contactless conductivity detector
20 November 2012,
09:27:36
Publication year:
2012
Source:Talanta
Dazhong Shen, Yaolong Li, Zhenli Zhang, Ping Zhang, Qi Kang
The impedance of a capacitively coupled contactless conductivity detector (C4D) in capillary electrophoresis (CE) was measured by an impedance analysis method. The influence of solution conductivity and capillary dimension on impedance parameters was investigated. Under the experimental conditions used, 86–99.9% of the total impedance of a C4D is composed by its imaginary part from the capillary wall capacitor. With increasing inner diameter of capillary and solution conductivity in detection zone, the wall capacitance increases, which results in the increase in the response signal of C4D. But the wall capacitance is only 0.5–12% of the predicted value according to a cylinder capacitor model. As the change in solution resistance is detected in a resonant C4D (RC4D), the sensitivity of contactless conductivity detection in CE is improved. The application of an end-to-end differential RC4D (DRC4D) system in CE was demonstrated in the determination of ten amino acids. The running buffer consisted of 2M acetic acid and 0.1% hydroxyethylcellulose (pH2.1). The limit of detection for amino acids is in the range of 0.1–0.4μM. Under our experimental conditions, the sensitivity of DRC4D enhances by a factor of 15–29as compared with C4D.
Source:Talanta
Dazhong Shen, Yaolong Li, Zhenli Zhang, Ping Zhang, Qi Kang
The impedance of a capacitively coupled contactless conductivity detector (C4D) in capillary electrophoresis (CE) was measured by an impedance analysis method. The influence of solution conductivity and capillary dimension on impedance parameters was investigated. Under the experimental conditions used, 86–99.9% of the total impedance of a C4D is composed by its imaginary part from the capillary wall capacitor. With increasing inner diameter of capillary and solution conductivity in detection zone, the wall capacitance increases, which results in the increase in the response signal of C4D. But the wall capacitance is only 0.5–12% of the predicted value according to a cylinder capacitor model. As the change in solution resistance is detected in a resonant C4D (RC4D), the sensitivity of contactless conductivity detection in CE is improved. The application of an end-to-end differential RC4D (DRC4D) system in CE was demonstrated in the determination of ten amino acids. The running buffer consisted of 2M acetic acid and 0.1% hydroxyethylcellulose (pH2.1). The limit of detection for amino acids is in the range of 0.1–0.4μM. Under our experimental conditions, the sensitivity of DRC4D enhances by a factor of 15–29as compared with C4D.
Highlights
► The sensitivity of contactless conductivity detector in capillary electrophoresis is improved. ► The dependence of wall capacitance on solution conductivity and capillary dimension is reported. ► Capillary electrophoresis with end-to-end differential detection is reported. ► The responses of different contactless conductivity detectors are compared.Evaluation of the performance of the determination of anions in the water soluble fraction of atmospheric aerosols
20 November 2012,
09:27:36
Publication year:
2012
Source:Talanta
Alejandro Arias, Ricardo J.N. Bettencourt da Silva, M.Filomena G.F.C. Camões, Cristina M.R.R. Oliveira
Abstract The knowledge of the mass of particulate matter in air, its chemical composition and emission sources is of relevance for taking decisions concerning air quality management in urban areas. The interpretation of these data is a function of the quality of the measurement results expressed by their uncertainties. This study aimed at developing models of the performance of the determination of anions in the water-soluble fraction of atmospheric aerosols, capable of determining, separately, the contribution of aerosols sampling, extraction of water-soluble fraction of atmospheric aerosols and quantification, by ion chromatography, of anions in the extract. The sampling procedure was assessed from the dispersion of results of duplicate parallel sampling after subtracting the analytical component of this dispersion. These models are used to evaluate the adequacy of the measurement procedure for the determination of urban aerosol composition and to support strategies for reducing measurement uncertainty or cost of analysis. The method performance was studied for the following ranges considering extract dilution up to five times: 0.23–8µgm−3 for chloride and nitrate, and 0.093–3.25µgm−3 for sulphate. Measurements are fit for the analysis of urban aerosols since the relative expanded measurement uncertainty is smaller than a maximum value of 40%. The percentage contribution of the uncertainty components varies with the analyte and its mass concentration, the major components being 24–93% for the extraction, 43–59% for sampling, 0.2–28% for the interpolation of the sample signal in the calibration curve and 4–8% for air volume measurement. The typical composition of analysed air is: (1.12±0.26) µgm−3, (1.02±0.30) µgm−3 and (0.76±0.22) µgm−3 of chloride, nitrate and sulphate in the water soluble fraction of aerosol respectively, for a confidence level of approximately 95% considering a coverage factor of 2.
Source:Talanta
Alejandro Arias, Ricardo J.N. Bettencourt da Silva, M.Filomena G.F.C. Camões, Cristina M.R.R. Oliveira
Abstract The knowledge of the mass of particulate matter in air, its chemical composition and emission sources is of relevance for taking decisions concerning air quality management in urban areas. The interpretation of these data is a function of the quality of the measurement results expressed by their uncertainties. This study aimed at developing models of the performance of the determination of anions in the water-soluble fraction of atmospheric aerosols, capable of determining, separately, the contribution of aerosols sampling, extraction of water-soluble fraction of atmospheric aerosols and quantification, by ion chromatography, of anions in the extract. The sampling procedure was assessed from the dispersion of results of duplicate parallel sampling after subtracting the analytical component of this dispersion. These models are used to evaluate the adequacy of the measurement procedure for the determination of urban aerosol composition and to support strategies for reducing measurement uncertainty or cost of analysis. The method performance was studied for the following ranges considering extract dilution up to five times: 0.23–8µgm−3 for chloride and nitrate, and 0.093–3.25µgm−3 for sulphate. Measurements are fit for the analysis of urban aerosols since the relative expanded measurement uncertainty is smaller than a maximum value of 40%. The percentage contribution of the uncertainty components varies with the analyte and its mass concentration, the major components being 24–93% for the extraction, 43–59% for sampling, 0.2–28% for the interpolation of the sample signal in the calibration curve and 4–8% for air volume measurement. The typical composition of analysed air is: (1.12±0.26) µgm−3, (1.02±0.30) µgm−3 and (0.76±0.22) µgm−3 of chloride, nitrate and sulphate in the water soluble fraction of aerosol respectively, for a confidence level of approximately 95% considering a coverage factor of 2.
Highlights
► Performance of the characterisation of atmospheric aerosols is assessed. ► Differential approach of the evaluation of the measurement uncertainty is used. ► Sampling and extraction uncertainty are estimated separately. ► Strategies for measurement uncertainty and cost of analysis reduction are proposed. ► Measurements are fit for the analysis of aerosols since present adequate uncertainty.Comparison of On-Line Detectors for Field Flow Fractionation Analysis of Nanomaterials
20 November 2012,
09:27:36
Publication year:
2012
Source:Talanta
A.J. Bednar, A.R. Poda, D.M. Mitrano, A.J. Kennedy, E.P. Gray, J.F. Ranville, C.A. Hayes, F.H. Crocker, Steevens
Characterization of nanomaterials must include analysis of both size and chemical composition. Many analytical techniques, such as dynamic light scattering (DLS), are capable of measuring the size of suspended nanometer-sized particles, yet provide no information on the composition of the particle. While Field Flow Fractionation (FFF) is a powerful nanoparticle sizing technique, common detectors used in conjunction with the size separation, including UV, light-scattering, and fluorescence spectroscopy, do not provide the needed particle compositional information. Further, these detectors do not respond directly to the mass concentration of nanoparticles. The present work describes the advantages achieved when interfacing sensitive and elemental specific detectors, such as Inductively Coupled Plasma Atomic Emission Spectroscopy and Mass Spectrometry, to FFF separation analysis to provide high resolution nanoparticle sizing and compositional analysis at the μg/L concentration level, a detection at least 10 to 100 fold lower than DLS or FFF-UV techniques. The full benefits are only achieved by utilization of all detector capabilities, such as dynamic reaction cell (DRC) ICP-MS. Such low-level detection and characterization capability is critical to nanomaterial investigations at biologically and environmentally relevant concentrations. The techniques have been modified and applied to characterization of all 4 elemental constituents of Cadmium Selenide Zinc Sulfide core-shell quantum dots, and silver nanoparticles with gold seed cores. Additionally, sulfide coatings on silver nanoparticles can be detected as a potential means to determine environmental aging of nanoparticles.
Source:Talanta
A.J. Bednar, A.R. Poda, D.M. Mitrano, A.J. Kennedy, E.P. Gray, J.F. Ranville, C.A. Hayes, F.H. Crocker, Steevens
Characterization of nanomaterials must include analysis of both size and chemical composition. Many analytical techniques, such as dynamic light scattering (DLS), are capable of measuring the size of suspended nanometer-sized particles, yet provide no information on the composition of the particle. While Field Flow Fractionation (FFF) is a powerful nanoparticle sizing technique, common detectors used in conjunction with the size separation, including UV, light-scattering, and fluorescence spectroscopy, do not provide the needed particle compositional information. Further, these detectors do not respond directly to the mass concentration of nanoparticles. The present work describes the advantages achieved when interfacing sensitive and elemental specific detectors, such as Inductively Coupled Plasma Atomic Emission Spectroscopy and Mass Spectrometry, to FFF separation analysis to provide high resolution nanoparticle sizing and compositional analysis at the μg/L concentration level, a detection at least 10 to 100 fold lower than DLS or FFF-UV techniques. The full benefits are only achieved by utilization of all detector capabilities, such as dynamic reaction cell (DRC) ICP-MS. Such low-level detection and characterization capability is critical to nanomaterial investigations at biologically and environmentally relevant concentrations. The techniques have been modified and applied to characterization of all 4 elemental constituents of Cadmium Selenide Zinc Sulfide core-shell quantum dots, and silver nanoparticles with gold seed cores. Additionally, sulfide coatings on silver nanoparticles can be detected as a potential means to determine environmental aging of nanoparticles.
Highlights
► Simultaneous multi-element detection of nanomaterials. ► Quantum Dot 4 element detection. ► Environmentally relevant concentrations of nanomaterials. ► Fate and transformation. ► Coating formation, and transformation, and detection.Colorimetric determination of thiram based on formation of gold nanoparticles using ascorbic acid
20 November 2012,
09:27:36
Publication year:
2012
Source:Talanta
S. Rastegarzadeh, Sh. Abdali
A novel optical method for the determination of thiram has been developed using surface plasmon resonance peak of gold nanoparticles (AuNPs). The stable and dispersed AuNPs were directly synthesized by reduction of HAuCl4 with ascorbic acid in micellar media according to a simple approach. The presence of thiram during formation of AuNPs results in the decrease of the intensity of plasmon resonance peak. The variation in the plasmon absorbance allows the colorimetric determination of thiram. The effect of different variables such as pH, ascorbic acid and CTAB concentrations was studied and optimized. The proposed method is capable of determining thiram over a range of 2.0×10−7−1.0×10−5 molL−1 with a limit of detection 1.7×10−7 molL−1. The relative standard deviation of the method was <3.7%. The method was successfully applied to the determination of thiram in water and plant seed samples.
Source:Talanta
S. Rastegarzadeh, Sh. Abdali
A novel optical method for the determination of thiram has been developed using surface plasmon resonance peak of gold nanoparticles (AuNPs). The stable and dispersed AuNPs were directly synthesized by reduction of HAuCl4 with ascorbic acid in micellar media according to a simple approach. The presence of thiram during formation of AuNPs results in the decrease of the intensity of plasmon resonance peak. The variation in the plasmon absorbance allows the colorimetric determination of thiram. The effect of different variables such as pH, ascorbic acid and CTAB concentrations was studied and optimized. The proposed method is capable of determining thiram over a range of 2.0×10−7−1.0×10−5 molL−1 with a limit of detection 1.7×10−7 molL−1. The relative standard deviation of the method was <3.7%. The method was successfully applied to the determination of thiram in water and plant seed samples.
Highlights
► A novel optical method for sensitive spectrophotometric determination of thiram. ► First time ascorbic acid was used as reducer in detection method by AuNPs plasmon. ► The proposed method has a simple, fast and eco-friendly procedure. ► In contrast with citrate method, the AuNPs were formed in situe. ► The LOD is better than other methods based on spectrophotometric detection.Rapid Determination of Polycyclic Aromatic Hydrocarbons (PAHs) in Zebrafish Eleutheroembryos as a Model for the Evaluation of PAH Bioconcentration
20 November 2012,
09:27:36
Publication year:
2012
Source:Talanta
S. El-Amrani, J. Sanz-Landaluze, J. Guinea, C. Cámara
A simple and fast approach for a novel bioaccumulation test by exposing zebrafish eleutheroembryos to fluorene and anthracene (PAHs) at two concentrations levels below 1% of their LC50 is presented. This alternative protocol sets an uptake period of 48 hours at 26°C for bioconcentration of the compounds tested and an additional 24 hours for depuration. Two different methods to estimate bioconcentration factors (BCFs) of PAHs were used. The first consists in the ratio between concentrations of the tested compounds in the zebrafish eleutheroembryos and the exposure media when a steady state during exposure is reached (BCFss). The second employs the concentration–time profile with the use of a least-square fit to a non-linear model (BCFk). A steady state (ss) was reached after 12 hours and 22 hours for fluorene and anthracene exposure, respectively. Uptake and depuration rate constants obtained were similar for the two exposure levels tested, hence toxicokinetic rate constants appeared to be independent of the exposure level. Bioconcentration factors of 1164 and 817 for fluorene exposure at 0.99ngmL−1 and 7.9ngmL−1 and of 2089 and 2344 for anthracene at 0.63ngmL−1 and 6.1ngmL−1 were assessed. The good agreement of the obtained results with those reported in the literature proves the feasibility of the proposed method for estimation of both toxicokinetic parameters and bioconcentration factors. Furthermore, this protocol, has potential to be an alternative to the OECD (Organisation for Economic Cooperation and Development) 305 method, considerably reducing time and associated costs of the test suggested by European legislation.
Source:Talanta
S. El-Amrani, J. Sanz-Landaluze, J. Guinea, C. Cámara
A simple and fast approach for a novel bioaccumulation test by exposing zebrafish eleutheroembryos to fluorene and anthracene (PAHs) at two concentrations levels below 1% of their LC50 is presented. This alternative protocol sets an uptake period of 48 hours at 26°C for bioconcentration of the compounds tested and an additional 24 hours for depuration. Two different methods to estimate bioconcentration factors (BCFs) of PAHs were used. The first consists in the ratio between concentrations of the tested compounds in the zebrafish eleutheroembryos and the exposure media when a steady state during exposure is reached (BCFss). The second employs the concentration–time profile with the use of a least-square fit to a non-linear model (BCFk). A steady state (ss) was reached after 12 hours and 22 hours for fluorene and anthracene exposure, respectively. Uptake and depuration rate constants obtained were similar for the two exposure levels tested, hence toxicokinetic rate constants appeared to be independent of the exposure level. Bioconcentration factors of 1164 and 817 for fluorene exposure at 0.99ngmL−1 and 7.9ngmL−1 and of 2089 and 2344 for anthracene at 0.63ngmL−1 and 6.1ngmL−1 were assessed. The good agreement of the obtained results with those reported in the literature proves the feasibility of the proposed method for estimation of both toxicokinetic parameters and bioconcentration factors. Furthermore, this protocol, has potential to be an alternative to the OECD (Organisation for Economic Cooperation and Development) 305 method, considerably reducing time and associated costs of the test suggested by European legislation.
Highlights
► Zebrafish eleutheroembryos is proven as a non-animal model to test bioaccumulation. ► For both PAHs tested, bioaccumulation factors obtained are in the medium-high range. ► Analytical methodology developed uses small sample amounts and low reagents consumption. ► Cost of proposed test is much lower than the official ones and much faster.Electrodeposition of poly(3,4-ethylenedioxythiophene) on a stainless steel wire for solid phase microextraction and GC determination of some esters with high boiling points
20 November 2012,
09:27:36
Publication year:
2012
Source:Talanta
Yuyu Ma, Faqiong Zhao
In this work, 3,4-ethylenedioxythiophene (EDOT) emulsion is prepared by ultrasonication agitation and poly(3,4-ethylenedioxythiophene) (PEDOT) coating is fabricated on a stainless steel wire by electrochemical method from a 0.10M sodium dodecyl benzenesulfonate aqueous solution containing EDOT. The coating is characterized by scanning electron microscopy and Fourier transform infrared spectrophotometry, and it presents cauliflower-like structure. When the resulted PEDOT/steel fiber is used for the headspace solid phase-microextraction of some esters (i.e. methyl anthranilate, dimethyl phthalate, ethyl-o-aminobenzoate, methyl laurate, diethyl phthalate) and their GC detection, the limits of detection (LOD) are ca. 7.8–31ngL−1(S/N=3) and the linear ranges are 0.25–800μgL−1. The fiber shows high thermal stability (up to 320°C), good reproducibility and long lifetime (more than 183 times). It also has good chemical stability. After it is immersed in acid, alkali and dichloromethane for 4 hours its extraction efficiency remains almost unchanged. Besides esters the fiber also exhibits high extraction efficiency for alcohols and aromatic compounds.
Source:Talanta
Yuyu Ma, Faqiong Zhao
In this work, 3,4-ethylenedioxythiophene (EDOT) emulsion is prepared by ultrasonication agitation and poly(3,4-ethylenedioxythiophene) (PEDOT) coating is fabricated on a stainless steel wire by electrochemical method from a 0.10M sodium dodecyl benzenesulfonate aqueous solution containing EDOT. The coating is characterized by scanning electron microscopy and Fourier transform infrared spectrophotometry, and it presents cauliflower-like structure. When the resulted PEDOT/steel fiber is used for the headspace solid phase-microextraction of some esters (i.e. methyl anthranilate, dimethyl phthalate, ethyl-o-aminobenzoate, methyl laurate, diethyl phthalate) and their GC detection, the limits of detection (LOD) are ca. 7.8–31ngL−1(S/N=3) and the linear ranges are 0.25–800μgL−1. The fiber shows high thermal stability (up to 320°C), good reproducibility and long lifetime (more than 183 times). It also has good chemical stability. After it is immersed in acid, alkali and dichloromethane for 4 hours its extraction efficiency remains almost unchanged. Besides esters the fiber also exhibits high extraction efficiency for alcohols and aromatic compounds.
Highlights
► A poly(3,4-ethylenedioxythiophene) (PEDOT) coating is prepared by electrochemical method. ► It shows cauliflower-like structure and has large surface area and high mass-transport rate. ► When it is used for SPME, it presents high stability and extraction efficiency for esters. ► This is a new way to make use of different monomers to prepare SPME fibers.A novel composite film derived from cysteic acid and PDDA-functionalized graphene: Enhanced sensing material for electrochemical determination of metronidazole
20 November 2012,
09:27:36
Publication year:
2012
Source:Talanta
Weilu Liu, Jianfu Zhang, Cong Li, Liu Tang, Zhiquan Zhang, Ming Yang
A novel composite film derived from cysteic acid and poly(diallydimethylammonium chloride)-functionalized graphene (PDDA-GN) was employed as an enhanced electrode material for ultrasensitive determination of metronidazole. The cysteic acid/PDDA-GN composite film was prepared by the electrochemical grafting of cysteic acid onto the PDDA-GN coated glassy carbon electrode (GCE). The cyclic voltammetry investigations reveal that the peak current of metronidazole reduction at the cysteic acid/PDDA-GN/GCE was remarkably enhanced compared to the bare GCE, the cysteic acid/GCE and the PDDA-GN/GCE. This result implies the synergistic electrocatalytic effect of cysteic acid and PDDA-GN. The fabricated sensor shows linear response to metronidazole in the ranges of 10nM - 1µM and 70µM - 800µM, with a detection limit of 2.3nM (S/N=3). The heterogeneous electron transfer rate constant and the diffusion coefficient of metronidazole were further evaluated by rotating disk electrode experiments. Moreover, we applied the present method to the determination of metronidazole in urine and lake water with satisfactory results.
Source:Talanta
Weilu Liu, Jianfu Zhang, Cong Li, Liu Tang, Zhiquan Zhang, Ming Yang
A novel composite film derived from cysteic acid and poly(diallydimethylammonium chloride)-functionalized graphene (PDDA-GN) was employed as an enhanced electrode material for ultrasensitive determination of metronidazole. The cysteic acid/PDDA-GN composite film was prepared by the electrochemical grafting of cysteic acid onto the PDDA-GN coated glassy carbon electrode (GCE). The cyclic voltammetry investigations reveal that the peak current of metronidazole reduction at the cysteic acid/PDDA-GN/GCE was remarkably enhanced compared to the bare GCE, the cysteic acid/GCE and the PDDA-GN/GCE. This result implies the synergistic electrocatalytic effect of cysteic acid and PDDA-GN. The fabricated sensor shows linear response to metronidazole in the ranges of 10nM - 1µM and 70µM - 800µM, with a detection limit of 2.3nM (S/N=3). The heterogeneous electron transfer rate constant and the diffusion coefficient of metronidazole were further evaluated by rotating disk electrode experiments. Moreover, we applied the present method to the determination of metronidazole in urine and lake water with satisfactory results.
Highlights
► Facile microwave-heating procedure for preparing PDDA-functionalized graphene. ► Cysteic acid/PDDA-functionalized graphene composite film as a new electrode material. ► High electrocatalytic activity for metronidazole reduction. ► Wide linear range, low detection limit for the determination of metronidazole. ► Application in practical samples with satisfactory results.Quenching effect on gold nano-patterned cardiac troponin I chip by total internal reflection fluorescence microscopy
20 November 2012,
09:27:36
Publication year:
2012
Source:Talanta
Seungah Lee, Seong Ho Kang
Total internal reflection fluorescence microscopy (TIRFM) was investigated for enhanced detection sensitivity of cardiac troponin I (cTnI) on a gold nano-patterned protein chip. A 4×5 nanoarray patterning of a gold chip based on a single-molecule sandwich immunoassay was prepared with a spot diameter of 500nm on glass substrates formed via electron-beam nanolithography. Quantitative trace analysis was possible as a function of increasing total internal reflection fluorescence intensity in the range of 84aM - 350pM at prism-type and 35aM - 350pM at objective-type TIRFM, respectively. Although using same gold nano-patterned cTnI chips, however, the objective-type TIRFM showed enhanced detection sensitivities 2.4 times better than the prism-type due to weaker gold quenching. This result is also about 7,000 times lower in the detection limit compared with those obtained by conventional commercial sandwich enzyme-linked immunosorbent assay techniques.
Source:Talanta
Seungah Lee, Seong Ho Kang
Total internal reflection fluorescence microscopy (TIRFM) was investigated for enhanced detection sensitivity of cardiac troponin I (cTnI) on a gold nano-patterned protein chip. A 4×5 nanoarray patterning of a gold chip based on a single-molecule sandwich immunoassay was prepared with a spot diameter of 500nm on glass substrates formed via electron-beam nanolithography. Quantitative trace analysis was possible as a function of increasing total internal reflection fluorescence intensity in the range of 84aM - 350pM at prism-type and 35aM - 350pM at objective-type TIRFM, respectively. Although using same gold nano-patterned cTnI chips, however, the objective-type TIRFM showed enhanced detection sensitivities 2.4 times better than the prism-type due to weaker gold quenching. This result is also about 7,000 times lower in the detection limit compared with those obtained by conventional commercial sandwich enzyme-linked immunosorbent assay techniques.
Highlights
► Quenching effects on gold nano-patterned chips with a spot diameter of 500 nm. ► Quantitative analysis of cTnI using the prism- and objective-type TIRFM. ► Stronger quenching efficiency in the prism- than in the objective-type TIRFM. ► Improved detection sensitivity of cTnI at the aM concentration level.On-line solid phase extraction using organic-inorganic hybrid monolithic columns for the determination of trace β-lactam antibiotics in milk and water samples
20 November 2012,
09:27:36
Publication year:
2012
Source:Talanta
Yun Zhang, Haiyan Liu, Xiaoyan Zhang, Huan Lei, Bai, Yang
A rapid and simple method with online solid phase extraction (SPE) has been developed for the simultaneous determination of beta-lactam antibiotics (BLAs) (amoxicillin, cephradine, and cefazolin sodium) in aquatic environment and milk. The epoxy-based organic-inorganic hybrid monolithic column was used as SPE sorbent to simultaneously monitor three analytes. The morphology of monolithic column and pressure drop across the columns were characterized. Excellent permeability and high selectivity was obtained. The linear range of the standard curve was from 2.0 to 500ng/mL (r2≥ 0.999). Precision for inter- and intra-day assay showed acceptable results for quantitative assay with relative standard deviation (RSD) less than 11%. The accuracy and recovery were found to be within the range of 93–103% and 83–105%. The results indicated that the prepared monolithic column could provide excellent reproducibility and implied that the prepared monolith was feasible to be used as an on-line SPE sorbent material.
Source:Talanta
Yun Zhang, Haiyan Liu, Xiaoyan Zhang, Huan Lei, Bai, Yang
A rapid and simple method with online solid phase extraction (SPE) has been developed for the simultaneous determination of beta-lactam antibiotics (BLAs) (amoxicillin, cephradine, and cefazolin sodium) in aquatic environment and milk. The epoxy-based organic-inorganic hybrid monolithic column was used as SPE sorbent to simultaneously monitor three analytes. The morphology of monolithic column and pressure drop across the columns were characterized. Excellent permeability and high selectivity was obtained. The linear range of the standard curve was from 2.0 to 500ng/mL (r2≥ 0.999). Precision for inter- and intra-day assay showed acceptable results for quantitative assay with relative standard deviation (RSD) less than 11%. The accuracy and recovery were found to be within the range of 93–103% and 83–105%. The results indicated that the prepared monolithic column could provide excellent reproducibility and implied that the prepared monolith was feasible to be used as an on-line SPE sorbent material.
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