2014 Bunsen-Kirchhoff Award for Analytical Spectroscopy

Annoucement

The DASp – German Working group for Applied Spectroscopy - regularly awards the "Bunsen-Kirchhoff-Preis für analytische Spektroskopie" to honour preferably the work of young scientists from universities, research institutes or industry who made excellent contributions to analytical spectroscopy. Especially preferred is an oeuvre in new areas like spectroscopy in nano compartments, spectroscopy of biomolecules a.s.o. The Award consists of an award-document and an amount of € 2.500,00 sponsored by Perkin Elmer and the DASp seeks nominations for the 2014 Bunsen-Kirchhoff Award for Analytical Spectroscopy. The Award will be presented at the Analytica in April 2014 in Munich (Germany).

A nomination (in electronic form) should include:

  1. letter with the candidate´s accomplishments

  2. list of publications or recent work,

  3. scientific curriculum vitae stating the age of the candidate; the candidate´s address, phone fax and e-mail.

Nominations can be made by members of DASp but eligibility is open for any scientist meeting the requirements. Self-nomination is excluded. The decision as to whom the prize is to be awarded shall be made by a jury consisting of the current members of the board of DASp.

Further information is available at:

https://www.gdch.de/netzwerk-strukturen/fachstrukturen/analytische-chemie/arbeitskreise/ak-dasp.html

All documents should be sent not later than 15 December 2013 to: Prof. Dr. Detlef Günther, President of the Jury for the Bunsen-Kirchhoff Award 2014, ETH Zürich, Laboratorium für Anorganische Chemie, Wolfgang-pauli-Str. 10, HCI G113, CH-8093 Zürich (Schweiz) 

E-Mail: Secretary, Ms Nicole Bachmann (nbachmann@inorg.chem.ethz.ch

Just Published: Sensors & Actuators B: Chemical

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Sensors & Actuators B: Chemical
http://rss.sciencedirect.com/publication/science/5283

Selected papers from the latest issue:

A novel way for detection of eugenol via poly (diallyldimethylammonium chloride) functionalized graphene-MoS2 nano-flower fabricated electrochemical sensor

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Qingliang Feng , Kaiyue Duan , Xiaoliang Ye , Daban Lu , Yongling Du , Chunming Wang
Poly (diallyldimethylammonium chloride) functionalized graphene-MoS2 nano-flower materials (PDDA-G-MoS2) were successfully synthesized, in which the addition of MoS2 wrinkling the graphene further increased the specific surface area. Then, the gold nanoparticles (AuNPs) were assembled on the surface of PDDA-G-MoS2 via electrostatic attractive force and function of AuS bond. The obtained Au/PDDA-G-MoS2 nanomaterial was used to modify glassy carbon electrode (Au/PDDA-G-MoS2/GCE) and determine sensitively eugenol. The oxidation peak currents increased distinctly on the proposed electrochemical sensor by cyclic voltammetry (CV) in 0.10molL⁻¹ NaAc-HAc buffer solution (pH=5.50), indicating that the material shows excellent electrochemical properties. The reaction kinetics was studied and the experimental conditions were optimized. The oxidation peak current of eugenol increased linearly with addition of concentration in the range from 0.1 to 440μmolL⁻¹ with a low detection limit of 0.036μmolL⁻¹ (S/N =3). This sensor exhibited high sensitivity, good stability and fast responses, and also has been applied to determination of eugenol in real samples with satisfactory results. The novel PDDA functionalization graphene-MoS2 nanoflower shows excellent electrocatalysis for determination of eugenol and satisfactory dispersity in water than graphene; these would show its potential application in analysis, medical science and nanodevice field via combining graphene with graphene-like materials (MoS2) for its novel properties.

Graphical abstract

Dual signaling of azide ions by deprotection of a dichlorofluorescein chloroacetate

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Jung Woo Lee , Ho Won Kim , Hyun Gyu Im , Hong Yeong Kim , Suk-Kyu Chang
We investigated the dual optical signaling of azide ions by the selective cleavage of fluorescein acetates. The chloroacetate derivative of 2′,7′-dichlorofluorescein showed prominent colorimetric and fluorogenic signaling behaviors toward azide ions in aqueous acetonitrile solution. Fluorescein analogs also showed a selective response, but the signaling speed was unfavorably slow. The detection of azide ions was not affected by the presence of commonly encountered anions. In particular, significant interference from sulfide ions in the azide-selective signaling of the probe was readily suppressed by using a Hg(II)–N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) complex as a masking agent. The detection limit for the determination of azide ions by the chloroacetate of 2′,7′-dichlorofluorescein in 10% aqueous acetonitrile was 4.0×10⁻⁷ M (17ppb). The signaling of azide ions in real samples using tap water and simulated wastewater was also tested.

Graphical abstract

Characterization of a new fluorescence-enhancing substrate for microarrays with femtomolar sensitivity

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Marina Cretich , Clelia Galati , Lucio Renna , Guglielmo Guido Condorelli , Paola Gagni , Marcella Chiari
The demand for high sensitivity in microarray technology has stimulated the research of new labeling strategies, new substrates with increased loading capacity and new approaches to amplify the fluorescence signals. Although these methods improve the sensitivity, they are based on non-routine procedures which limit their widespread usage. A simple way to achieve fluorescence enhancement is the optical interference (OI) coating technology based on the use of substrates with films of well-defined thickness that maximize photoabsorption of the dye molecules in the vicinity of the surface and reflect the emitted light toward the detector. Here we introduce a new substrate for fluorescence enhancement composed of a thin aluminum mirror and a single quarter wave silicon oxide as a dielectric layer. The use of such material allows the development of a substrate suited for parallel production in conventional IC (Integrated Circuit's) technology, which produces a 20-fold enhancement of fluorescence compared to glass, which is the most common material used in microarrays. The new substrate was coated with a copolymer of N,N-dimethylacrylamide, N-acryloyloxysuccinimide, and 3-(trimethoxysilyl)propyl methacrylate, copoly(DMA-NAS-MAPS), which forms, by a simple and robust procedure, a functional nanometric film that covalently binds bio-probes on the surface and efficiently suppresses non-specific adsorption. The performance of the new fluorescence-enhancing substrate in microarray technology was demonstrated for the detection of a panel of inflammation biomarkers pushing detection limits into the femtomolar range.

Measurement of the evolution of rigid and viscoelastic mass contributions from fibrin network formation during plasma coagulation using quartz crystal microbalance

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Ramji S. Lakshmanan , Vitaly Efremov , Sinéad M. Cullen , Anthony J. Killard
The coagulation of blood plasma and the effect of fibrinogen concentration were studied with a quartz crystal microbalance (QCM), where frequency and half-width at half-maximum (bandwidth) values measured from the conductance spectrum near resonant frequency were used. Bandwidth change is an indicator of energy dissipation, allowing for an understanding of qualitative changes occurring during fibrin clot formation. Both frequency shift (Δf) and bandwidth shift (ΔΓ) were dependent on the concentration of fibrinogen in plasma. We defined a sum of squares function α (=Δf ²/1000+ΔΓ ²/1000) that measures absolute changes in QCM resonant characteristics to semi-quantitatively include an overall contribution of adsorbed mass and elastic modulus components and a function β (=1−ΔΓ/Δf) that indicates qualitatively the nature of response based on its deviation from ideal Newtonian behaviour. Increasing concentration of fibrinogen resulted in an increase in the value of α, showing that a larger amount of fibrinogen results in larger amount of coupled viscoelastic mass. Changes in β indicated that the nature of changes occurring was very similar to Newtonian and that coupling of rigid-mass dominates the overall response in the early stage of coagulation and in the later stage growing elastic mass compensates some of the response.

A novel BODIPY-based colorimetric and fluorometric dual-mode chemosensor for Hg2+ and Cu2+

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Xingxing He , Jing Zhang , Xungao Liu , Lin Dong , Di Li , Huayu Qiu , Shouchun Yin
A novel BODIPY-based colorimetric fluorescent sensor with bis[2-(phenylseleno)ethyl]amine as binding site (Se-1) for Hg²⁺ and Cu²⁺ has been developed. Se-1 shows high selectivity and sensitivity toward Hg²⁺ and Cu²⁺ over alkali and transition metal ions. Se-1shows a significant red-shift in the absorption spectra from 525 to 571nm for Hg²⁺ and 590nm for Cu²⁺, which induces color changes from pink to purple and blue. Upon excitation at 570nm, Se-1 upon interaction with Hg²⁺ ions displays a 5-fold fluorescence enhancement with a 2nm blue-shift, while Se-1 with Cu²⁺ exhibits a 13-fold fluorescence enhancement and red-shifts from 595 to 610nm. The binding mode of Se-1 with Hg²⁺ or Cu²⁺ has been investigated by Job's plot, ESI and ¹H NMR experiments. The absorption and fluorescence of the Se-1–Hg²⁺ complex can be reversibly restored to that of the uncomplexed ligand by using EDTA or cysteine, however, the sensing processing of Se-1 in response to Cu²⁺ ions cannot.

A microfluidic device for the hydrodynamic immobilisation of living fission yeast cells for super-resolution imaging

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Laurence Bell , Ashwin Seshia , David Lando , Ernest Laue , Matthieu Palayret , Steven F. Lee , David Klenerman
We describe a microfluidic device designed specifically for the reversible immobilisation of Schizosaccharomyces pombe (Fission Yeast) cells to facilitate live cell super-resolution microscopy. Photo-Activation Localisation Microscopy (PALM) is used to create detailed super-resolution images within living cells with a modal accuracy of >25nm in the lateral dimensions. The novel flow design captures and holds cells in a well-defined array with minimal effect on the normal growth kinetics. Cells are held over several hours and can continue to grow and divide within the device during fluorescence imaging.

Synthesis of Ag-MoS2/chitosan nanocomposite and its application for catalytic oxidation of tryptophan

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Xiaohong Xia , Zhixiang Zheng , Yan Zhang , Xiaojuan Zhao , Chunming Wang
A convenient and low-cost synthesis approach is proposed for the development of a simple and novel electrochemical sensor for the determination of tryptophan (Try). In this synthesis process, graphene-like molybdenum sulfide was successfully obtained, and silver nanoflakes (AgNFs) were directly synthesized on the surface of molybdenum sulfide (MoS2) films, in this process chitosan (CS) and ascorbic acid (AA) acted as the stabilizer and reducing agent, respectively. This nanocomposite was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed to evaluate the electrochemical property of Ag-MoS2/CS toward the oxidation of tryptophan. Under the optimized experimental conditions, the oxidation peak currents are proportional to the concentrations of tryptophan over the range of 0.5μM to 120μM, and the detection limit is 0.05μM (S/N=3). Moreover, the proposed method is free of interference from other amino acid to other coexisting species.

Polymeric optodes based on upconverting nanorods for fluorescence measurements of Pb2+ in complex samples

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Jing Wu , Yu Qin
We reported here a lead ion selective optode incorporating NaYF4: Er,Yb upconverting nanorods, chromoionophore ETH 5418, and lead ionophore together in hydrophobic polymer matrixes. The absorption spectra of protonated and unprotonated ETH 5418 overlap the two emission peaks of the upconverting material, respectively, which allows the fluorescent ion sensing based on the inner filter effect. The proposed optodes exhibited highly selective and reproducible sensing property for measuring lead ions in the range of 10⁻⁶–10⁻² M at pH 5. Because the excitation source is 980nm and the emission wavelength lies in the near-infrared region, the sensors have been successfully used in complex samples for example plasma with minimized background absorption and sample autofluorescence. The lead levels in sheep plasma and artificial industry wastewater samples obtained by the optode were comparable with the known addition amounts of Pb(NO3)2, providing a new method for testing Pb²⁺ in the industry wastewater.

GADH screen-printed biosensor for gluconic acid determination in wine samples

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Lorena del Torno-de Román , M. Asunción Alonso-Lomillo , Olga Domínguez-Renedo , Arrate Jaureguibeitia , M. Julia Arcos-Martínez
Gluconate dehydrogenase (GADH) biosensors have been developed for the satisfactory determination of gluconic acid in wine samples, without any pretreatment. The biosensors have been fabricated by cross-linking immobilization of GADH onto screen-printed carbon electrodes, containing the mediator tetrathiafulvalene (TTF). Chronoamperograms have been registered at +100mV vs. screen-printed Ag/AgCl electrode by successive additions of a gluconic acid solution in the concentration range from 9.0 to 131.4μM. This method shows a reproducibility of 8.1% (n =3) related to the slopes of these calibration curves and a repeatability of 3.2% (n =5). The procedure has shown an average capability of detection of 9.0μM for a probability of false positive and negative of 0.05. Wine samples have been analyzed with these biosensors, obtaining satisfactory results.

Volume-doped cobalt titanates for ethanol sensing: An impedance and X-ray absorption spectroscopy study

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Clemens J. Belle , Günter E. Wesch , Stefan Neumeier , M. Janeth Lozano-Rodríguez , Andreas C. Scheinost , Ulrich Simon
The dynamic C2H5OH sensitivity of ilmenite-type cobalt titanates volume-doped by 2at% Li, Na, K, Sb, La, Sm, Gd, Ho and Pb was systematically studied with respect to exhaust monitoring. Therefore, the p-type semiconducting CoTiO3 materials were characterized as resistive gas sensors via high-throughput impedance spectroscopy toward 5–200ppm C2H5OH at 300–500°C. The best performing materials were tested further by time-resolved and long-term measurements whereby the CoTiO3 volume-doped with K exhibited an outstanding overall performance. X-ray absorption spectroscopy on this particular material gave evidence that the local structure around Co and Ti remains unaffected by the doping despite of a slight increase in static disorder. Hence, the effect of K doping does not originate from alteration in the metal-to-oxygen interaction as expected from previous findings.

Validation of wavelength modulation spectroscopy techniques for oxygen concentration measurement

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): S. Neethu , R. Verma , S.S. Kamble , J.K. Radhakrishnan , P.P. Krishnapur , V.C. Padaki
Tunable Diode Laser Absorption Spectroscopy (TDLAS) based gas sensing technology, has widespread applications, ranging from use in biomedical industry to aerospace applications. An experimental set-up was established to measure concentration of oxygen gas in the range 0–100% using TDLAS technique. The oxygen absorption at 760.241nm was scanned with a tunable DFB laser, and wavelength modulation spectroscopy was used to obtain the harmonics (1f, 2f, 3f & 4f) of the oxygen absorption signal. The modulation parameters such as the modulation voltage, modulation frequency, reference phase, time constant of lock in amplifier, the tuning voltage, and the tuning frequency were optimized to obtain the harmonics of high amplitude and narrow half width. Keeping the experimental parameters constant, the oxygen concentration measurements were obtained by the following three methodologies, viz, (i) using only the 2nd harmonic, (ii) using the 2nd and 4th harmonics and, (iii) using the 1st and 2nd harmonics. The results of these measurements were compared and the merits and drawbacks of these methods are discussed.

Colorimetric determination of DNA concentration and mismatches using hybridization-mediated growth of gold nanoparticle probes

20 November 2013, 08:11:22

Publication date: 1 March 2014
Source:Sensors and Actuators B: Chemical, Volume 192
Author(s): Wei-Feng Fang , Wen-Jone Chen , Jing-Tang Yang
A novel colorimetric approach to sense DNA samples was demonstrated successfully based on a concept of hybridization-mediated growth of gold nanoparticles probes (AuNP probes). The growth size and conformation of the probes are dominated by DNA samples that hybridize with the probes. The growth probes serve as nanoparticle biosensors that can be utilized to analyze concentrations of DNA samples or to discriminate mismatches of DNA samples to the probes (complementarity of DNA) in terms of size- and shape-dependence optical properties. By means of the proposed method, not only the semi-quantitation of target DNA but also the differentiation of DNA mismatches can be readily achieved with a naked eye or simple spectrophotometer. This method features small consumption of reagents, a satisfactory detection limit (about 60nM), a small duration of assay (a couple of minutes), and a simple procedure without thermal control. 

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Hold the front page!

A paper entitled, Determination of selected biogenic amines in Acacia rigidulaplant materials and dietary supplements using LC–MS/MS methods published in the Journal of Pharmaceutical & Biomedical Analysis has made the front page of national newspaper, USA Today (see this link http://www.usatoday.com/story/news/nation/2013/11/18/fda-scientists-find-amphetamine-like-compound-in-dietary-supplements/3627963/).

The paper was published in Volume 88, 25 January 2014, Pages 457–466 and can be found here:

http://www.sciencedirect.com/science/article/pii/S0731708513004378

Just Published: Sensors & Actuators A: Physical

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Sensors & Actuators A: Physical
http://rss.sciencedirect.com/publication/science/5282

Selected papers from the latest issue:

Self-writing smart labels for humidity monitoring

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): Christian Schoo , Meinhard Knoll
Lateral anodic oxidation is a recent display technique with potential usage in self-writing smart labels and switching applications, which have the ability to operate with established RFID units. This process requires water to operate, which is harvested by a hygroscopic electrolyte layer from the ambient atmosphere. This precondition enables the realization of a humidity monitoring functionality. We develop smart labels displaying the maximum relative humidity during a period of time by the usage of halides providing different hygroscopicity in the electrolyte layer. Therefore we investigate the behavior of the humidity monitoring smart labels under test conditions with diverse relative humidity.

Color sensing ability of an amorphous silicon position sensitive detector array system

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): Javier Contreras , Rodrigo Martins , Pawel Wojcik , Sergej Filonovich , Hugo Aguas , Luis Gomes , Elvira Fortunato , Isabel Ferreira
The color sensing ability of a data acquisition prototype system integrating a 32 linear array of 1D amorphous silicon position sensitive detectors (PSD) was analyzed. Besides being used to reproduce a 3D profile of highly reflective surfaces, here we show that it can also differentiate primary red, green, blue (RGB) and derived colors. This was realized by using an incident beam with a RGB color combination and adequate integration times taking into account that a color surface mostly reflects its corresponding color. A mean colorimetric error of 25.7 was obtained. Overall, we show that color detection is possible via the use of this sensor array system, composed by a simpler amorphous silicon pin junction.

Investigation of guided surface acoustic wave sensors by analytical modeling and perturbation analysis

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): Onursal Onen , Rasim Guldiken
In this paper, shear horizontal polarized guided surface acoustic wave propagation was investigated with analytical modeling and perturbation analysis for biosensing applications. The model was also verified experimentally. The analytical model was developed for multilayer systems taking viscoelasticity into consideration. Detailed parametric investigation of dispersion curves was conducted using various substrate materials and guiding layers. The effects of frequency and degree of viscoelasticity were also studied. Perturbation equations were developed with first order approximations by relating the dispersion curve slopes to sensitivity. Among the guiding layers investigated, Parylene C showed the highest sensitivity followed by gold, chrome and silicon dioxide. The perturbation investigations were also extended to protein layers for immunosensing applications. It was observed that viscous behavior resulted in slightly higher sensitivity, and protein layers showed almost identical sensitivity similar to polymers investigated (SU-8, Parylene, etc.). The optimum configuration is found to be Parylene-C guiding layer on a ST-cut quartz substrate for protein layer sensing and this configuration has 40 times the sensitivity of gold guiding layer on quartz substrate. Our results indicate that chrome and silicon dioxide have low sensitivity when used as guiding layers. Also, lithium tantalate substrate with gold and Parylene-C guiding layers results in ∼10% lower sensitivity as compared to quartz substrate.

MEMS based normally closed silicon microregulator for gas and water

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): B. Pramanick , S. Das , T.K. Bhattacharyya
This paper presents the design, fabrication and performance evaluation of a normally closed piezoelectrically actuated silicon microregulator. The microregulator is realized using two wafers process and is designed for the maximum operating pressure 5bar and it is found to be leak proof (1×10⁻⁴ sccm of helium gas).This paper also reports the development of precision fixturing, assembling and testing of the valve. One of the potential areas for application of microregulators is in satellite propulsion using ion thrusters. Ion thrusters require feed systems with very precise propellant gas flow rate and it makes microregulator a suitable candidate. Another application of the microregulator is liquid propellant flow control in micropropulsion. The water flow measurement of the same microregulator is discussed here. The hysteresis measurement of the silicon membrane using inductive probe and the cyclic test of the microregulator are also described here.

A novel compliant micropositioning stage with dual ranges and resolutions

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): Qingsong Xu
Dual-range stages are demanded in precision positioning applications that call for fine resolution in a smaller motion range and coarse resolution in a larger range. Traditional dual-range stages are realized using two actuators, which complicates the mechanism and control design procedures. This paper presents the design and testing of a novel dual-range, dual-resolution precision positioning stage driven by a single linear actuator. The stage structure is devised with leaf flexures to achieve a large stroke. Strain sensors are employed to provide different resolutions in the two motion ranges. To quantify the design of the motion ranges and fine/coarse resolution ratio, analytical models are established and verified through finite element analysis simulations. A proof-of-concept prototype is fabricated for experimental investigations and the experimental results validate the effectiveness of the proposed design. The reported ideas can also be extended to the design of multi-axis micropositioning stages.

Design and analysis of a 2D broadband vibration energy harvester for wireless sensors

19 November 2013, 09:42:19

Publication date: 1 January 2014
Source:Sensors and Actuators A: Physical, Volume 205
Author(s): Jin Yang , Xihai Yue , Yumei Wen , Ping Li , Qiangmo Yu , Xiaoling Bai
This paper presents a design for a novel vibration energy harvester using a magnetoelectric (ME) transducer, which is efficiently applicable in two-dimensional (2D) motion and over a range of vibration frequencies. This harvester adopts a circular cross-section cantilever rod to extract the ambient vibration energy because of its ability to host accelerations in arbitrary motion directions. Moreover, the magnetic interactions between the magnets and the ME transducer will lead to the nonlinear oscillation of the rod with increased frequency bandwidth. The influences of the nonlinear vibration factor and magnetic field distribution on the electrical output and bandwidth of the harvester are investigated to achieve optimal vibration energy harvesting performances. The experimental results showed that, the harvester was sensitive to the vibration with arbitrary in-plane directions. With an acceleration of 0.6g (where g =9.8ms⁻²), it had the working bandwidths of 4.2Hz, 2.6Hz, 2.3Hz, 2.5Hz and 3.2Hz, and the output powers of 0.6mW, 0.49mW, 0.33mW, 0.5mW and 0.56mW at the in-plane excitation angles of−90°, −45°, 0°, 45° and 90°, respectively.

Design and evaluation of a skin-like sensor with high stretchability for contact pressure measurement

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): Debao Zhou , Haopeng Wang
This paper presents the development of a new type of skin-like tactile pressure sensor array. The sensor array is scalable, flexible and stretchable and can measure pressure up to 250kPa within 30% stretching rate without damaging its mechanical structure. It can also conform to irregular three-dimensional surfaces. The sensor array consists of three layers. The top and bottom layers are formed by the array of parallel conductive strips made of silver nanowires (AgNWs) embedded in polydimethylsiloxane (PDMS) thin films. The AgNWs/PDMS conductor strips are used as stretchable interconnections to transmit electrical signals. The middle layer is made of PDMS. This film is pre-molded with holes filling with cylinder-shaped conductive elastomer for pressure measurement. In this paper, the characteristic of the AgNWs/PDMS conductor strips as stretchable interconnections is studied. The piezoresistive properties of the sensels (one sensing element is called a sensel) were measured and discussed. The performance of the tactile sensor array under stretching was also tested. With the associated scanning power-supply circuit and data acquisition system, it is demonstrated that the system can successfully capture the tactile images induced by objects of different shapes. Such sensor system could be applied on curved or non-planar surfaces in robots or medical devices for force detection and feedback.

Improvement of the off-diagonal magnetoimpedance sensor white noise

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): M. Malatek , B. Dufay , S. Saez , C. Dolabdjian
This work deals with the analysis of noise sources of the off-diagonal magneto-impedance sensor with stress-annealed amorphous ribbon. This experimental analysis shows that the equivalent magnetic noise spectral density is mostly due to the electronic conditioning circuitry that operates the sensor. The electronic noise was then reduced with employment of an improved excitation-detection technique for our sensor and an equivalent magnetic noise spectral density below 1 pT / Hz in white noise region has been reached. Indeed, the equivalent magnetic white noise level of the output signal decreased from 5 pT / Hz to 560 fT / Hz . Nevertheless, this noise level is still limited by the electronic conditioning, leaving room for further improvement.

Laser-unzipped carbon nanotube based glucose sensor for separated structure of enzyme modified field effect transistor

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): Wan-Lin Tsai , Yun-Shan Chien , Po-Yu Yang , I-Che Lee , Kuang-Yu Wang , Huang-Chung Cheng
A glucose sensing film composed of unzipped multiwalled carbon nanotubes (MWCNTs) via continuous-wave laser irradiation is investigated. Some structural defects decorate on MWCNTs after an acid treatment, and the MWCNTs are unzipped into sheet-shaped layers initiated from these defects after the laser irradiation. The laser-irradiated carbon nanotube thin films (CNTFs) possess higher conductance owing to larger contact area, and the side edges of unzipped CNTs could act as sensing sites for hydrogen ions. Thus the laser-irradiated CNTF as a glucose sensing film could achieve a higher sensitivity of 0.302mV(mg/dl)⁻¹, equal to 7.55mV(mg/dl)⁻¹ per centimeter square, and a larger linearity of 0.9947 than the as-sprayed one. Moreover, the fully low-temperature processes of this work also reveal the potentials for flexible and disposable biosensors.

Highly enhanced piezoelectric properties of PLZT/PVDF composite by tailoring the ceramic Curie temperature, particle size and volume fraction

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): Peng Han , Shengli Pang , Jingbo Fan , Xiangqian Shen , Tiezheng Pan
Piezoelectric oxides Pb1−x La x (Zr y Ti1−y )1−x/4O3 (PLZT) were synthesized by the solid-state reaction process and Pb0.96La0.04(Zr0.54Ti0.46)0.99O3/polyvinylidene fluoride (PL0.04ZT/PVDF), Pb0.92La0.07(Zr0.555Ti0.445)0.9825O3/PVDF (PL0.07ZT/PVDF) composites with various particle sizes and contents (50–90vol.%) of the ceramic phase were prepared by the hot-press process. The Curie temperature (T c ) of PLZT decreases monotonously from 312°C to 98°C with La content (x) increasing from 0.02 to 0.09. The polarizability of PLZT/PVDF composites increases from 39.5% (PL0.04ZT/PVDF) to 56.7% (PL0.07ZT/PVDF) when poled at 125°C (at the vicinity of T c of PL0.07ZT). As a result, the electrical property improvement with d 33 (ɛ r ) from 53pC/N (159) to 76pC/N (222) proves that tailoring T c of the piezoelectric ceramic to the poling temperature is a useful way to enhance the piezoelectric and dielectric properties of the ceramic/polymer composite. To further investigate the electrical properties of the 0–3 type PLZT/PVDF composite, the particle size and volume fraction of PLZT are also optimized.

Nanometer scale active ground motion isolator

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): R. Le Breton , G. Deleglise , J. Allibe , A. Badel , G. Balik , B. Caron , A. Jeremie , J. Lottin , S. Vilalte
Vibration isolation is a critical issue in various precision engineering fields. A new design of an active isolation system operating heavy loads (up to 50kg) is presented in this work. This system provides state of the art vibration isolation at the nanometer scale for magnets of a future particle accelerator and is more compact than other studies in this field. The choice of sensors and actuators, the mechanical design and the acquisition electronics are investigated in order to reject ground motion efficiently. A dynamic experimental characterization is performed. Based on the identified model, a specific controller, giving an attenuation between 10Hz and 100Hz was designed and experimentally qualified.

Development of an auto-calibrated interfacing circuit for thick film multi-gas sensor

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): R. Khakpour , M.N. Hamidon , G.A.E. Vandenbosch
A simple, cheap, and integrated architecture is introduced to measure gases with a thick film gas sensor. The temperatures of the sensors are stabilized by controlling the heaters of the sensors. The heaters’ temperatures are measured by sampling the heaters resistance through the use of a voltage divider and ADCs. A microcontroller accordingly adjusts the output of DACs in order to apply the appropriate steering voltage to the heaters. The method employed to measure the gases is to sample the voltage drop over the resistances of the sensors, which are depending on the gases, by ADCs. The innovation lies in the simplicity of the design and the use of different simple methods and commercially available technologies to fabricate the circuit. Also, a single microcontroller is used to drive and control the heaters’ temperature, to compensate ambient temperature of the heaters, to measure and monitor the amount of gases detected by sensors and finally, to select the sensors. This opens the possibility to use these gas sensors for monitoring purposes at a large scale, for example in alarms and computers.

Development of piezoelectric coaxial filament sensors P(VDF-TrFE)/copper for textile structure instrumentation

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): M.B. Kechiche , F. Bauer , O. Harzallah , J.-Y. Drean
Coaxial filaments based on Poly (vinylidene fluoride-co-trifluoroethylene) and copper filament was developed, their mechanical properties characterized. They were then instrumented in textile structure and their detection capabilities were observed. P(VDF-TrFE)/copper coaxial filaments were obtained by a melt spinning process, the mechanical drawing applied at the end of spinning process enabled the increasing of the crystalline β phase from 43% for the copolymer in pellet shape to 52% for the developed coaxial filament of 250μm in diameter. Coaxial filaments surfaces and sections have been analyzed with a scanning electron microscope. The mechanical properties have been quantified by tensile analyses. Coaxial filaments were polarized by the ISL process in order to correlate the level of the polarization with the piezoelectric activity. The textile instrumentation was tested by the integration of some samples in the weft direction of a weaving structure using an industrial weaving machine (Muller NCE 10). An example of electrical signal delivered by integrated filament in textile when subjected to strain and stress actions is shown.

A multi-frequency vibration-based MEMS electromagnetic energy harvesting device

19 November 2013, 09:42:19

Publication date: 15 December 2013
Source:Sensors and Actuators A: Physical, Volume 204
Author(s): Huicong Liu , You Qian , Chengkuo Lee
A multi-frequency vibration-based MEMS electromagnetic energy harvesting (EH) device has been presented, fabricated and characterized in this paper. It consists of a permanent magnet and a circular suspension structure on a MEMS EH chip. By emulating the magnetic field of a cylinder magnet, the gap distance between the magnet and EH chip is optimized to be zero for achieving larger magnetic flux change and higher output performance. From the experimental results, the vibration energy can be harvested at three excitation frequencies of 840, 1070 and 1490Hz, which corresponds to the out-of-plane (mode I), torsion (mode II/III) and in-plane (mode IV/V) vibrations of the EH device, respectively. The maximum power densities at these three frequencies are 0.157, 0.014 and 0.117μW/cm³, respectively, for a matched load resistance of 626Ω and an input acceleration of 1.0g. The feasibility study results show promising application potentials for harvesting energy from vibrations of multi-frequency.  

Starter Kit for SPE Sample Preparation

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Just Published: Microchemical Journal

A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:

Microchemical Journal
http://rss.sciencedirect.com/publication/science/6599

Selected papers from the latest issue:

Laboratory controlled study of the uptake and release of vanadium by oysters (Crassostrea virginica)

17 November 2013, 20:10:18

Publication date: March 2014
Source:Microchemical Journal, Volume 113
Author(s): Joel C. Richert , Carey J. Hardaway , Joseph Sneddon
Preliminary investigation of the uptake and removal of vanadium by oysters in a controlled laboratory environment showed that this occurs although the extent was difficult to quantify due to losses attributed to possible precipitation and the oyster shells impacting on the results. Nevertheless results did indicate that oysters can be affected (uptake) but can also purge (remove) vanadium in solution.

Classification of edible vegetable oil using digital image and pattern recognition techniques

17 November 2013, 20:10:18

Publication date: March 2014
Source:Microchemical Journal, Volume 113
Author(s): Karla Danielle Tavares Melo Milanez , Márcio José Coelho Pontes
This work presents a simple and non-expensive method based on digital image and pattern recognition techniques for the classification of edible vegetable oils with respect to the type (soybean, canola, sunflower and corn) and the conservation state (expired and non-expired shelf life). For this purpose, vegetable oil sample images were obtained from a webcam and the frequency distribution of color indexes in the red–green–blue (RGB), hue (H), saturation (S), intensity (I), and grayscale channels were obtained. Linear discriminant analysis (LDA) was employed in order to build classification models on the basis of a reduced subset of variables. For the purpose of variable selection, two techniques were utilized, namely the successive projection algorithm (SPA) and stepwise (SW) formulation. For the study evolving the classification with respect to oil type, LDA/SPA and LDA/SW models achieved a correct classification rate (CCR) of 95% and 90% respectively. For the identification of expired and non-expired samples, LDA/SPA models were found to be the best method for classifying sunflower, soybean and canola oils, achieving a CCR in the overall data set of 97%, 94% and 93%, respectively, while the LDA/SW correctly classified at 100% for corn oil data. These results suggest that the proposed method is a promising alternative for the inspection of authenticity and the conservation state of edible vegetable oils. As advantages, the method does not use reagents to carry out the analysis and laborious procedures for chemical characterization of the samples are not required.

Determination of reduced glutathione, cystein and total thiols in pine pollen powder by in situ derivatization

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Xiao-Yong Zhang , Yu-Lian Piao , Sheng-Yun Cui , Yong-Ill Lee
Glutathione (GSH), cystein (CySH) and total thiols in pine pollen powder were determined by spectrometric, fluorometric and high performance liquid chromatographic (HPLC) assays utilizing 5,5′-dithio-bis(2-nitrobenzoic acid) (DTNB, Ellman's reagent) and o-phthaldehyde (OPA) as derivatizing agents. The pollen samples were extracted with phosphate buffer solutions (PBS) containing excess derivatizing agents concomitant with ultrasonic cell rupture. In this way, thiol groups in the samples could be effectively blocked by in situ formation of relatively stable derivatizing products just after the pollen cell ruptured, thereby effectively preventing thiol groups from oxidation during sample preparation and making it possible to perform sensitive and accurate detections. Using a precolumn derivatization method, DTNB, GSH and CySH, as well as other thiol compounds can be determined or estimated by the HPLC method. Total thiols in the samples were determined by the spectrometric method using DTNB as the derivatizing agent. GSH was also selectively determined by the fluorometric method using OPA as the derivatizing agent. The detection results indicated that abundant thiol compounds, such as GSH, CySH and thiol protein, existed in pine pollen powder with measured amounts of 0.50–0.53μmol∙g⁻¹ of GSH, 0.41μmol∙g⁻¹ of CySH and 4.15μmol∙g⁻¹ of total thiols.

Flow injection hydride generation for on-atomizer trapping: Highly sensitive determination of cadmium by tungsten coil atomic absorption spectrometry

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Piaopiao Chen , Yujia Deng , Kuncheng Guo , Xiaoming Jiang , Chengbin Zheng , Xiandeng Hou
Here we report the use of the tungsten-coil atomizer of a portable atomic absorption spectrometer as an on-atomizer trapping device and atomizer for the determination of trace cadmium, with flow injection hydride generation for production of volatile cadmium species from sample solutions. By mixing acidic analyte solution with tetrahydroborate solution, volatile cadmium species is produced and separated from the solution, and then transported and impacted onto the surface of the atomizer with a heating current set at 2.3A. Subsequent atomic absorption measurement was accomplished with in situ atomization at 8.5A. Compared to conventional direct injection, the sensitivity and the limit of detection were improved by 58- and 66-fold, respectively, based on 5.0mL sampling volume. In addition, use of flow injection significantly improved sample throughput. The proposed method was used for the analysis of several real water samples with good spiked recoveries.

Emerging issues on degradation by-products deriving from personal care products and pharmaceuticals during disinfection processes of water used in swimming pools

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Paola Bottoni , Lucia Bonadonna , Mattea Chirico , Sergio Caroli , Gyula Záray
The use of disinfection substances in the sanitation and disinfection processes of artificial water used for sports amenities and swimming pools has recently raised some serious concerns. Recreational Water Illnesses (RWIs) can put at serious risk the health of bathers and swimmers due to adverse effects caused by the use of disinfection chemicals, such as chlorine, chloramine, ozone and UV radiation, as well as their by-products. Remarkable documented evidence is available on the impact of Disinfection By-Products (DBPs), such as chloroform and other trihalomethanes, haloacetic acids and chlorophenols, deriving from the oxidation of common organic pollutants dissolved in raw, drinking, waste and artificial waters. Appropriate countermeasures, aimed at avoiding bathers' exposures to these chemicals, have been developed and adopted in public and private structures, also through important scientific contributions and technical provisions issued by the WHO and some national health authorities. On the other hand, it has been demonstrated that high reactive disinfection agents may transform other undesirable chemicals released by bathers, namely pharmaceuticals, sunscreens and other Pharmaceuticals and Personal Care Products (PPCPs) into chlorinated and oxidized compounds and nitrosamine precursors. The first symptoms of potentially adverse health effects on human subjects of these largely unknown by-products should be adequately taken into consideration and investigated.

Single-step procedure for trace element determination in synovial fluid by dynamic reaction cell-inductively coupled plasma mass spectrometry

17 November 2013, 20:10:1

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Franco Moyano , Ernesto Verni , Héctor Tamashiro , Silvia Digenaro , Luis D. Martinez , Raúl A. Gil
A fast and single-step procedure for the dissolution of human synovial fluid in formic acid and further determination by dynamic reaction cell-inductively coupled plasma mass spectrometry (DRC-ICPMS) with a high-efficiency sample introduction system was developed. The samples were collected, treated and analyzed in the same screw-capped tubes. In order to overcome the effect of considerable carbon content, the sample introduction, nebulization and ICP operating conditions were carefully optimized. Furthermore, DRC technology with CH4 as reaction gas was used for the elimination of spectral interferences due to polyatomic ions. The effect of the sample matrix was evaluated and mitigated through comparison of direct calibration against aqueous standards, direct calibration in formic acid media and analyte addition calibration. The recommended procedure involved low dilution and low detection limits (from 0.003μgL⁻¹ for U to 13.3μgL⁻¹ for Ti) with adequate precision (from 0.6% for Co to 6.6% for Ti). The proposed method was successfully applied to determine 16 trace elements in concentrations from 0.03μgL⁻¹ (Cd) to 88.2μgL⁻¹ (Cu) in human synovial fluid samples.

Modeling of second-order spectrophotometric data generated by a pH-gradient flow injection technique for the determination of doxorubicin in human plasma

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Mirta R. Alcaráz , Agustina V. Schenone , María J. Culzoni , Héctor C. Goicoechea
In this paper, the development of a pH-gradient flow-injection method with diode-array spectrophotometric detection combined with extended multivariate curve resolution–alternating least-squares (MCR–ALS) to quantitate doxorubicin in the presence of rifampicin in plasma samples is presented. Quantitation of doxorubicin was based on acid–base and spectral differences between its species and those for the interference. Overlapped profiles among the analyte and the interference were mathematically solved by data modeling with the well-known extended MCR–ALS algorithm. The method, which involves a simple sample pretreatment consisting in the addition of trichloroacetic acid followed by centrifugation, was applied to resolve validation mixtures composed of human plasma spiked with doxorubicin. Acceptable analytical figures of merit were obtained, i.e. recoveries from 96 to 107%, coefficients of variation between 0.2% and 7.8%, and limits of detection and quantification of 0.77 and 2.32μgL⁻¹, respectively.

Graphical abstract

Effects of UV-dechloramination of swimming pool water on the formation of disinfection by-products: A lab-scale study

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Nicolas Cimetiere , Joseph De Laat
UV dechloramination has become a very popular process for reducing the concentration of chloramines in public swimming pool water. As the effects of this process on the formation of disinfection by-products (DBPs) remain a controversial issue, a bench-scale study has been undertaken to examine the impact of UV dechloramination on the formation of various DBPs. Four pool water samples were exposed to UV radiation at 254nm in the presence of free chlorine ([Cl2]0 =3mgL⁻¹) and then chlorinated in the dark for 24h ([Cl2]0 =3mgL⁻¹). High UV doses (up to 47kJm⁻²) were used to simulate cumulative UV doses received by real pool waters. The data showed that UV irradiation led to a 90% photodecay of free chlorine for UV doses ranging from 13 to 20kJm⁻², to the formation of chlorate ion (0.05–0.11mol of chlorate/mole of free chlorine decomposed) and to a significant increase in the chlorine demand of pool water during the post-chlorination step. UV exposure followed by post-chlorination did not significantly affect the formation of haloacetic acids, led to a small increase in the concentrations of adsorbable organic halogen (AOX) and of chloral hydrate and markedly increased the formation of trihalomethanes (chloroform, bromodichloromethane, chlorodibromomethane), dichloroacetonitrile, 1,1,1-trichloropropanone and chloropicrin.

Preconcentration of toxic elements in artificial saliva extract of different smokeless tobacco products by dual-cloud point extraction

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Sadaf Sadia Arain , Tasneem Gul Kazi , Jamshed Bashir Arain , Hassan Imran Afridi , Kapil Dev Brahman , Naeemullah
Smokeless tobacco (SLT) has been associated with oral cancer. In present study, the total and artificial saliva extracted toxic elements (TEs), arsenic (As), cadmium (Cd), nickel (Ni) and lead (Pb) were estimated in SLT products (gutkha, green and brown snuff). Dual-cloud point extraction has been used for the preconcentration of As, Cd, Ni and Pb in artificial saliva extract, using complexing reagent, ammonium pyrrolidinedithiocarbamate. The dual-cloud point extraction procedure was based on forming complexes of elemental ions with complexing reagent and subsequent entrapping of the complexes in nonionic surfactant. Then the surfactant rich phase containing the complexes was treated with nitric acid, and detected ions were back extracted again into aqueous phase at the second cloud point extraction stage, and finally determined by electrothermal atomic absorption spectrometry. The validity of methodology was tested by simultaneously analyzing certified reference material and spike recovery test. The experimental enhancement factors of As, Cd, Ni and Pb were found to be 52, 58, 48 and 44, respectively. The concentration of As, Cd, Ni and Pb in artificial saliva extracts corresponds to 18–24, 45–75, 30–55, and 20–30%, respectively, of the total contents of TE in different types of SLT products (gutkha, brown and green snuff). It was estimated that 10g intake of SLT products (gutkha, brown and green snuff) could contribute 2.2–13, 21–69, 3.4–48 and 10–75% of the provisional maximum tolerable daily intake of As, Cd, Ni and Pb, respectively for adults ~60kg.

Determination of aluminum in botanical samples by adsorptive cathodic stripping voltammetry as Al-8-hydroxyquinoline complex

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Lídia B. Santos , Maisa T.F. de Souza , Alexandre T. Paulino , Edivaldo E. Garcia , Eurica M. Nogami , Juliana C. Garcia , Nilson E. de Souza
A fast and sensitive new procedure for the determination of total aluminum by adsorptive cathodic stripping voltammetry (AdCSV) in plant samples consumed for dietary and/or medicinal purposes was described. The Al(III)-8-hydroxyquinoline (Al-8HQ) complex was adsorbed on a hanging mercury dropping electrode (HMDE) at 0.300V versus Ag/AgCl electrode during a 30s accumulation time. An electrochemical cell containing 0.024molL⁻¹ ammonia–ammonium acetate buffer (pH6.80) as supporting electrolyte and 7.43mgL⁻¹ 8-hydroxyquinoline (8-HQ) as ligand for aluminum were employed. A linear response was observed over the 8.54×10⁻⁸ to 2.35×10⁻⁷ molL⁻¹ range with a limit of detection (LOD) of 8.54×10⁻⁸ molL⁻¹ and a relative standard deviation (RSD; n=3) of 1.86% for 8.54×10⁻⁸ molL⁻¹ aluminum solution. Aluminum contents in green tea (Camellia sinensis), carqueja (Baccharis genistelloides), cascara sagrada (Rhamnus purshiana) and senna (Cassia acutifolia) were 502.5±14.1, 195.6±21.0, 309.1±11.7, 205.6±16.1μg aluminum per g of dry tea, respectively. The accuracy of the developed method was evaluated by flame atomic absorption spectrometry (FAAS) and all of the results were similar. It indicates that AdCSV could be efficiently applied in the determination of aluminum as 8-HQ complex in real food samples.

Arsenic metabolites in human serum and urine after seafood (Anemonia sulcata) consumption and bioaccessibility assessment using liquid chromatography coupled to inorganic and organic mass spectrometry

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): M. Contreras-Acuña , T. García-Barrera , M.A. García-Sevillano , J.L. Gómez-Ariza
The present paper reports for the first time the bioaccessibility of arsenic species in Anemonia sulcata and its metabolization in the human body after the ingestion of this seafood, a delicacy highly appreciated in the south of Spain. Speciation in tissue extracts and human fluids was carried out by anion/cation exchange chromatography with inductively coupled plasma mass spectrometry ((IC)-ICP-MS). Results obtained show that about 54% of the arsenic present in the anemones is lost after cooking, around 95% of total arsenic in cooked anemones is bioaccessible and 85% of the amount ingested is eliminated from the body by urine in 90h. The relative abundance of As in urine varies along the time, but after the first 10h follows the order arsenobetaine (AB)≈DMA^V (dimethylarsinate)>arsenocholine (AsC)>tetra-methyl-arsonium (TETRA)>trimethyl-arsine oxide (TMAO)>MA^V (monomethylarsonate)>iAs^V >dimethylarsenoethanol (DMAE), while the major species in cooked anemones is AB followed by DMA^V >dimethylmonothioarsinic acid (DMAS^V)>AsC>TETRA>TMAO>iAs^V >glycerylphosphorylarsenocholine(GPAsC)>MA^V >DMA. After 30min from the ingestion, DMA^V is the most abundant in human serum, followed by AB, MA^V and AsC. Finally, the use of organic mass spectrometry allowed the standardless identification of AsC, GPAsC, DMAS^V and DMAE.

Legionella spp. survival after different disinfection procedures: Comparison between conventional culture, qPCR and EMA–qPCR

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): A. Mansi , I. Amori , I. Marchesi , A.M. Marcelloni , A.R. Proietto , G. Ferranti , V. Magini , F. Valeriani , P. Borella
The development of rapid and sensitive methods for the detection and quantification of Legionella viable cells is essential for monitoring water quality and preventing legionellosis. The aim of this study was to verify the applicability of a quantitative PCR (qPCR) method used in combination with ethidium monoazide (EMA) to the quantification of Legionella spp. in samples collected from swimming pools, water recirculation systems and hot water systems in two fitness clubs. This molecular technique (EMA–qPCR) allows the amplification of target DNA from culturable and viable cells, but prevents the amplification of DNA from non-viable cells. The effectiveness of this new method able to detect alive legionellae was also compared with conventional qPCR and culture method. Our results confirm that EMA–qPCR allows to discriminate the non-viable cells from those viable and that it is particularly indicated for monitoring the effectiveness of thermal treatments for the Legionella contamination control in water environments, also providing information about the presence of Viable But Non-Culturable (VBNC) cells. Other Gram-negative bacteria typically associated with biofilm were identified in samples taken from swimming pools and balance tanks, suggesting that also the presence of biofilm should be monitored for a more general view of water contamination.

The molecular enrichment approach for the identification of microbiological indicators in recreational waters

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): F. Valeriani , S. Giampaoli , V. Romano Spica
The identification of rapid methods for the surveillance of recreational waters and aquatic environments is necessary to provide adequate levels of health safety and quality standards. Molecular techniques have been proposed in recent years as a valuable alternative to traditional microbiological cultural methods, having numerous advantages (speed, specificity and sensibility). We have previously described a method for the detection of Staphylococcus aureus in recreational waters by a molecular enrichment approach, based on a two steps PCR performed on 23S rDNA. The approach has been now expanded to other microbiological indicators, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli. This methodological extension to other prokaryotic genomes has required a partial primer re-design and protocol optimization, in order to improve the assay. The usage of native not recombinant Taq-polymerases for detection of E. coli eliminated the background probably due to traces of the bacterial genome in many commercially available reagents. The obtained results clearly underline the feasibility of a fast and integrated molecular approach to quantify the standard biological indicators for assessment of safety and quality in recreational waters.

Identification of starch and determination of its botanical source in ancient manuscripts by MEKC–DAD and LDA

17 November 2013, 20:10:18

Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): M.E. Castillo-Valdivia , A. López-Montes , T. Espejo , J.L. Vílchez , R. Blanc
A simple and rapid Micellar Electrokinetic Capillary Chromatography method with UV diode-array detection (MEKC–DAD) has been developed for the identification of the two starch polysaccharides, amylopectin and amylose, in ancient manuscripts. Moreover, a linear discriminant analysis (LDA) has been used in order to determine the botanical source of the starch (wheat, maize or rice). The reason to develop this method is that starch has been used throughout history in paper manufacture as glue and sizing agent. The LDA was applied to the amylopectin/amylose ratio using the area and height data recorded. The separation was performed in an extended path-length fused-silica capillary (‘bubble capillary’) of 36cm in length and 50μm i.d.. The running buffer was composed of 20mM sodium acetate, 1.2mM I2, 7.2mM KI, and 50mM sodium dodecyl sulphate (SDS) at pH6. The potential applied was 22kV in positive polarity, the temperature was 25°C, and the detection was performed at 560nm. Injection of the samples was performed at 20mbar for 2s. An artificial ageing test was carried out in the three types of starch in order to determine the effect of the temperature, relative humidity and irradiance on this compound. The procedure was performed in an ageing chamber according to the ISO 5630-3:1996 and 11341:2004 standards. The methods were applied to samples from manuscripts preserved in the Historic Archive of the University of Granada and the Royal Chancellery Archive of Granada (Spain).