AMSBIO has expanded its range of rat specific ELISA kits that enable precise analysis of key neurodegenerative-related biomarkers while minimizing the use of precious samples.
Visitors to the recent Neuroscience 2011 meeting in Washington DC responded enthusiastically to AMSBIO's range of over 2300 rat specific ELISA kits tailored for the sensitive and specific quantification of your cytokine, growth factor, or chemokine of interest. Particular interest was shown in new rat specific analyte ELISA kits for various Neurotrophins, TGFb1 and rat leptin as well as a series of ganglioside ELISAs.
At this important meeting AMSBIO also showcased new products for innovative co-culturing of different neuronal cells together with a range of ELISA kits for Alzheimer's research enabling sensitive and specific detection of molecules including Amyloid Precursor Protein (APP) and Sialytransferase. Also on display were ELISA kits for well known neuroscience biomarkers including human IL-6, mouse BDNF, human TNFa, human IGF-1, human Fibronectin, human IL-10, human G-CSF, human VEGF, human MMP-9, human IL-1b, human MMP-2, human NGF, human MCP-1, human EGF, human IL-4, human GH and human M-CSF.
For a copy of AMSBIO's new Neuroscience catalogue please visit www.amsbio.com/brochures/Neuroscience_Tools_AMSBIO.pdf or contact the company on +44-1235-828200 / +1-949-768-8365 or email info@amsbio.com
This blog has been set up for editors, reviewers, authors and readers of Elsevier's Analytical Chemistry Journals - all of which can be seen below. It will be updated from Monday to Friday with general news and announcements concerning the titles listed on this page. It should be noted that the views or claims made in the news items and feeds are not necessarily those of the Publisher.
World Congress on Biosensors 2014
Biosensors 2014
Friday, 6 January 2012
Thursday, 5 January 2012
Just Published: Analytica Chimica Acta
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:
Selected papers from the latest issue:
Investigation of gamma radiation effect on the anion exchange resin Amberlite IRA-400 in hydroxide form by FTIR andC NMR spectroscopy
05 January 2012, 03:05:04
Publication year: 2012
Source: Analytica Chimica Acta, Available online 3 January 2012
A. Traboulsi, N. Dupuy, C. Rebufa, M. Sergent, V. Labed
Radiation-induced decomposition of the anion exchange resin Amberlite IRA-400 in hydroxide form by gamma radiolysis has been studied under different irradiation doses and irradiation atmospheres. In this work, we focused on the degradation of the solid part of the resin by Fourier Transformed Infra-Red (FTIR) andC Nuclear Magnetic Resonance (NMR) spectroscopies associated with chemometric treatments. FTIR andC NMR techniques showed that only −CH2N(CH3)3groups were detached from the resin whereas the polystyrene divinylbenzene backbone remains intact. The quaternary ammonium groups were replaced by amine or carbonyl groups according to the irradiation atmosphere (with or without water or oxygen). Principal Components Analysis (PCA) was used to classify the degraded resins according to their irradiation conditions by separating the effect of the dose or the environment. The PCA loadings have shown spectral regions which discriminate the irradiated resins whereas SIMPLe-to-use Interactive Self-modeling Mixture Analysis (SIMPLISMA) allows to identify families of component characterizing the chemical structure of resins and estimate their relative contributions according to the irradiation atmospheres.
Source: Analytica Chimica Acta, Available online 3 January 2012
A. Traboulsi, N. Dupuy, C. Rebufa, M. Sergent, V. Labed
Radiation-induced decomposition of the anion exchange resin Amberlite IRA-400 in hydroxide form by gamma radiolysis has been studied under different irradiation doses and irradiation atmospheres. In this work, we focused on the degradation of the solid part of the resin by Fourier Transformed Infra-Red (FTIR) andC Nuclear Magnetic Resonance (NMR) spectroscopies associated with chemometric treatments. FTIR andC NMR techniques showed that only −CH2N(CH3)3groups were detached from the resin whereas the polystyrene divinylbenzene backbone remains intact. The quaternary ammonium groups were replaced by amine or carbonyl groups according to the irradiation atmosphere (with or without water or oxygen). Principal Components Analysis (PCA) was used to classify the degraded resins according to their irradiation conditions by separating the effect of the dose or the environment. The PCA loadings have shown spectral regions which discriminate the irradiated resins whereas SIMPLe-to-use Interactive Self-modeling Mixture Analysis (SIMPLISMA) allows to identify families of component characterizing the chemical structure of resins and estimate their relative contributions according to the irradiation atmospheres.
Highlights
► Your works complete the existing studies on the γ-radiation impact on the Amberlite IR400 in OH form ► The irradiation effect under different conditions was determined from an experimental design ► Its structure was characterized by resolving FTIR andC NMR concatenated data from chemometric tools.►Principal Components Analysis discriminated influencing factors as doses and conditions ► SIMPLISMA allowed to identify the new chemical functional groups and their relative proportion.Determination of oxytetracycline in milk samples by polymer inclusion membrane separation coupled to high performance liquid chromatography
04 January 2012, 01:59:45
Publication year: 2012
Source: Analytica Chimica Acta, Available online 2 January 2012
Irma Pérez-Silva, José A. Rodríguez, Ma. Teresa Ramírez-Silva, Ma. Elena Páez-Hernández
The determination of oxytetracycline in milk samples using a polymer inclusion membrane concept with HPLC was studied. The membranes developed are composed by cellulose acetate as polymer base, Cyanex 923 as carrier and o-nitrophenyl octyl ether as plasticizer. In the optimal conditions, the method exhibits good linearity in the range 0.03-0.20 mg Lwith a limit of detection and quantification of 8.2 and 27.3 μg Lrespectively. The method was successfully applied to the analysis of milk samples with high selectivity.
Source: Analytica Chimica Acta, Available online 2 January 2012
Irma Pérez-Silva, José A. Rodríguez, Ma. Teresa Ramírez-Silva, Ma. Elena Páez-Hernández
The determination of oxytetracycline in milk samples using a polymer inclusion membrane concept with HPLC was studied. The membranes developed are composed by cellulose acetate as polymer base, Cyanex 923 as carrier and o-nitrophenyl octyl ether as plasticizer. In the optimal conditions, the method exhibits good linearity in the range 0.03-0.20 mg Lwith a limit of detection and quantification of 8.2 and 27.3 μg Lrespectively. The method was successfully applied to the analysis of milk samples with high selectivity.
Highlights
► Selective extraction and HPLC analysis of oxytetracycline OTC in milk samples. ► Preparation and characterization of a polymer inclusion membrane PIM. ► Optimization of PIM-HPLC method using a Plackett-Burman experimental design. ► The OTC was isolated and the matrix interferences were eliminated. ► Limit of detection useful for OTC residues analysis in real milk samples (8 ng mL).“Multi-way partial least-squares and residual bi-linearization for the direct determination of monohydroxy-polycyclic aromatic hydrocarbons on octadecyl membranes via room-temperature fluorescence excitation emission matrices
04 January 2012, 01:59:45
Publication year: 2012
Source: Analytica Chimica Acta, Available online 2 January 2012
Hector C. Goicoechea, Korina Calimag-Williams, Andres D. Campiglia
Multi-way partial least-squares (N-PLS) is combined to the residual bi-linearization procedure (RBL) for the direct analysis of metabolites of polycyclic aromatic hydrocarbons in urine samples. Metabolite analysis is carried out via a two-step experimental procedure based on solid-phase extraction and room temperature fluorescence spectroscopy. Excitation-emission matrices are recorded from octadecyl (C18) membranes that serve as solid substrates for sample extraction and spectroscopic measurements. Excellent metabolite recoveries were obtained in all cases, which varied from 96.2 ± 1.35% (9-hydroxyphenanthrene) to 99.7 ± 0.49% (3-hydroxybenzo[a]pyrene). Background correction of extraction membranes is carried out with a new alternating least-squares (ALS) procedure adapted to second order data. The performance of N-PLS/RBL is compared to the well-established multivariate curve resolution-alternating least-squares (MCR-ALS) algorithm. Both algorithms provided similar analytical figures of merit, including their ability to handle unknown interference in urine samples. With only 10 mL of sample, the limits of detection varied between 0.06-0.08 ng mL(1-hydroxypyrene) to 0.016–0.018 ng mL(2-hydroxyfluorene). When compared to previously reported univariate calibration data, the limits of detection via N-PLS/RBL and MCR-ALS are approximately one order of magnitude higher. This was somehow expected due to the effect of unexpected components in multivariate figures of merit, i.e. a more realistic approach to the analysis of metabolites in human urine samples
Source: Analytica Chimica Acta, Available online 2 January 2012
Hector C. Goicoechea, Korina Calimag-Williams, Andres D. Campiglia
Multi-way partial least-squares (N-PLS) is combined to the residual bi-linearization procedure (RBL) for the direct analysis of metabolites of polycyclic aromatic hydrocarbons in urine samples. Metabolite analysis is carried out via a two-step experimental procedure based on solid-phase extraction and room temperature fluorescence spectroscopy. Excitation-emission matrices are recorded from octadecyl (C18) membranes that serve as solid substrates for sample extraction and spectroscopic measurements. Excellent metabolite recoveries were obtained in all cases, which varied from 96.2 ± 1.35% (9-hydroxyphenanthrene) to 99.7 ± 0.49% (3-hydroxybenzo[a]pyrene). Background correction of extraction membranes is carried out with a new alternating least-squares (ALS) procedure adapted to second order data. The performance of N-PLS/RBL is compared to the well-established multivariate curve resolution-alternating least-squares (MCR-ALS) algorithm. Both algorithms provided similar analytical figures of merit, including their ability to handle unknown interference in urine samples. With only 10 mL of sample, the limits of detection varied between 0.06-0.08 ng mL(1-hydroxypyrene) to 0.016–0.018 ng mL(2-hydroxyfluorene). When compared to previously reported univariate calibration data, the limits of detection via N-PLS/RBL and MCR-ALS are approximately one order of magnitude higher. This was somehow expected due to the effect of unexpected components in multivariate figures of merit, i.e. a more realistic approach to the analysis of metabolites in human urine samples
Highlights
► We apply N-PLS/RBL to the analysis of metabolites of polycyclic aromatic hydrocarbons in urine. ► C18 membranes are used for sample extraction and solid substrates for spectroscopic measurements. ► Quantification is made via room-temperature fluorescence excitation emission matrices. ► N-PLS/RBL and RTF-EEM successfully address the issue of spectral overlapping on solid substratesOLYMPUS Stream Solutions provide you with the perfect recipe to determine steel quality
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Wednesday, 4 January 2012
Versatile CHN Analyzer for Environmental Applications
The Model 440 Elemental Analyzer from Exeter Analytical is capable of precisely analyzing the widest range of environmental sample types for percentage levels of carbon, hydrogen and nitrogen - quickly, easily and reliably.
Its unique horizontal furnace design, allowing for removal of residues between runs, prevents cross contamination and enables in excess of 1000 samples to be run between combustion tube changes. Effectively eliminating troublesome residue build-up the gas flow characteristics of the Model 440 analyzer are superior to other elemental analysers thereby also providing longer-term calibration stability as well as enhanced accuracy and precision for measured sample data.
Beneficially the Model 440 provides the capacity to process air and water monitoring filters up to 50mm in diameter in one analytical cycle. By comparison other elemental analysers, employing vertical furnace designs, require larger filters to be sub sampled several times and then corrective calculations made to enable analysis.
As the Model 440 provides complete control over combustion parameters it is able to reproducibly achieve 100% combustion with the widest range of sediment samples. For sediment samples with low levels of Nitrogen in the 0.1-0.2% range, proprietary Nitrogen analysis software uniquely enables accurate measurement at these levels with a high degree of accuracy.
Traditional methodologies for determining CHN content of soil, plant and insect samples typically use macro-CHN or Kjehldahl Nitrogen analysis. While both these techniques are proven to generate useful data, both have drawbacks. Macro-CHN analysers are relatively expensive to purchase and run compared to micro-CHN systems and Kjehldahl requires use of highly corrosive and toxic chemicals. Using a Model 440 elemental analyzer several leading crop research institutes are routinely able to accurately and precisely determine the CHN content of a wide range of soil, plant and insect materials using samples sizes of typically 2 - 20mg.
Low gas and reagent consumption combined with high reduction tube life allows the Model 440 to deliver some of the lowest operating costs of any CHN elemental analyzer available. Intuitive Windows based operating software reduces human errors through incorporation of extensive automation, comprehensive customer help and diagnostic facilities. Most parts on the Model 440 are user replaceable further reducing operating costs and downtime.
As a company dedicated to elemental microanalysis, Exeter Analytical's 25+ years of involvement with instruments, consumables and supplies has allowed them to better understand the whole problem facing microanalysts. As a consequence whether you are a regular or an occasional purchaser - experienced and knowledgeable staff are always available to provide free informed advice.
For further information on environmental analysis using the Model 440 CHN Elemental Analyzer please contact Exeter Analytical on +44-2476-323223 (Europe / Asia), +1-978-251-1411 (North America / ROW) or email info@exeteranalytical.co.uk.
Its unique horizontal furnace design, allowing for removal of residues between runs, prevents cross contamination and enables in excess of 1000 samples to be run between combustion tube changes. Effectively eliminating troublesome residue build-up the gas flow characteristics of the Model 440 analyzer are superior to other elemental analysers thereby also providing longer-term calibration stability as well as enhanced accuracy and precision for measured sample data.
Beneficially the Model 440 provides the capacity to process air and water monitoring filters up to 50mm in diameter in one analytical cycle. By comparison other elemental analysers, employing vertical furnace designs, require larger filters to be sub sampled several times and then corrective calculations made to enable analysis.
As the Model 440 provides complete control over combustion parameters it is able to reproducibly achieve 100% combustion with the widest range of sediment samples. For sediment samples with low levels of Nitrogen in the 0.1-0.2% range, proprietary Nitrogen analysis software uniquely enables accurate measurement at these levels with a high degree of accuracy.
Traditional methodologies for determining CHN content of soil, plant and insect samples typically use macro-CHN or Kjehldahl Nitrogen analysis. While both these techniques are proven to generate useful data, both have drawbacks. Macro-CHN analysers are relatively expensive to purchase and run compared to micro-CHN systems and Kjehldahl requires use of highly corrosive and toxic chemicals. Using a Model 440 elemental analyzer several leading crop research institutes are routinely able to accurately and precisely determine the CHN content of a wide range of soil, plant and insect materials using samples sizes of typically 2 - 20mg.
Low gas and reagent consumption combined with high reduction tube life allows the Model 440 to deliver some of the lowest operating costs of any CHN elemental analyzer available. Intuitive Windows based operating software reduces human errors through incorporation of extensive automation, comprehensive customer help and diagnostic facilities. Most parts on the Model 440 are user replaceable further reducing operating costs and downtime.
As a company dedicated to elemental microanalysis, Exeter Analytical's 25+ years of involvement with instruments, consumables and supplies has allowed them to better understand the whole problem facing microanalysts. As a consequence whether you are a regular or an occasional purchaser - experienced and knowledgeable staff are always available to provide free informed advice.
For further information on environmental analysis using the Model 440 CHN Elemental Analyzer please contact Exeter Analytical on +44-2476-323223 (Europe / Asia), +1-978-251-1411 (North America / ROW) or email info@exeteranalytical.co.uk.
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:
Selected papers from the latest issue:
Numerical and analytical modelling of holed MEMS resonators
30 December 2011, 02:38:01
Publication year: 2011
Source: Sensors and Actuators A: Physical, Available online 29 December 2011
Y. Civet, F. Casset, J.F. Carpentier, S. Basrour
After consistently progress in Micro-Electro-Mechanical (MEM) resonators, Silicon oscillators are finally being commercialized for time and frequency control applications not requiring huge frequency accuracy. Indeed, they offer size reduction, potentially low cost and CMOS integration. However, frequency shift because of holes, unavoidable for MEMS release or damping effects, is still one of the challenges to address high frequency accuracy applications. In this article, we present the mechanical modelling of holed clamped-clamped (CC) beam resonators. An analytical and a numerical model have been developed to obtain the frequency variations due to holes onto resonant structures. We note a good agreement between both models, presenting less than 1.5% of deviation. We also report the manufacturing of holed clamped-clamped beam resonators in only six major steps using compatible CMOS process. Electrical tests have been performed to check the functionality of our structures. Finally, electrical measurements and analytical model have been compared and a discrepancy less than 0.4% is reported. Analytical models validation enables designers to benefit from a powerful vibrating MEMS design tool, including the influence of holes onto resonant structures for any kinds of applications from sensors to actuators and oscillators.
Source: Sensors and Actuators A: Physical, Available online 29 December 2011
Y. Civet, F. Casset, J.F. Carpentier, S. Basrour
After consistently progress in Micro-Electro-Mechanical (MEM) resonators, Silicon oscillators are finally being commercialized for time and frequency control applications not requiring huge frequency accuracy. Indeed, they offer size reduction, potentially low cost and CMOS integration. However, frequency shift because of holes, unavoidable for MEMS release or damping effects, is still one of the challenges to address high frequency accuracy applications. In this article, we present the mechanical modelling of holed clamped-clamped (CC) beam resonators. An analytical and a numerical model have been developed to obtain the frequency variations due to holes onto resonant structures. We note a good agreement between both models, presenting less than 1.5% of deviation. We also report the manufacturing of holed clamped-clamped beam resonators in only six major steps using compatible CMOS process. Electrical tests have been performed to check the functionality of our structures. Finally, electrical measurements and analytical model have been compared and a discrepancy less than 0.4% is reported. Analytical models validation enables designers to benefit from a powerful vibrating MEMS design tool, including the influence of holes onto resonant structures for any kinds of applications from sensors to actuators and oscillators.
Highlights
► modelling of holed clamped-clamped (CC) beam resonators ► manufacturing of holed clamped-clamped beam resonators in only six major ► Electrical tests performed ► electrical measurements and analytical model have been compared.Physically cross-linked cellulosic gel via 1-butyl-3-methylimidazolium chloride ionic liquid and its electromechanical responses
30 December 2011, 02:38:01
Publication year: 2011
Source: Sensors and Actuators A: Physical, Available online 29 December 2011
Wissawin Kunchornsup, Anuvat Sirivat
Cellulose shows promising piezoelectric properties widely used in electroactive papers (EAPaps), however its solubility still remains a challenging problem. 1-Butyl-3-methylimidazolium Chloride (BMIMCl), a well-known room temperature ionic liquid (RTIL), is utilized here to dissolve a micro-crystalline cellulose. The BMIMCl- cellulose gels are prepared by the solvent casting method. The elctromechanical properties of the cellulose gels are investigated under the oscillatory shear mode at electric field strengths between 0 to 1 kV/mm and as functions of temperature. The storage modulus (Ǵ) increases linearly with temperature up to 333 K at 1 rad/s in the absence of electric field strength. The storage moduli (Ǵ) also increase linearly with temperature up to 313 K at 1 rad/s in the presence of 1 kV/mm of electric field strength and decreases above 313 K, consistent with the behavior of dielectric permittivity (ɛ́). The elastic-plastic-viscous transition is observed in the presence of 1 kV/mm. It is shown that the conditions imposed by electric field strength and temperature alter the transition temperature, and lower the dielectric constant, the storage modulus, and the actuation performance. In the deflection experiments, under applied DC electric field, the deflection distances of the gels linearly increase with increasing electric field strength along with the dielectrophoresis forces above the electrical yield strength of 100 V/mm. The back and forth swinging occurs under the constant electric field strength between 525-550 V/mm due to the competition between the anion and cation movements within the ionic liquid. Electrostatic force microscope (EFM) is then employed to investigate the gel topology and the cationic channel and aggregation that control the actuation behavior. The Phy gel is shown here to be promising for actuator applications over other existing dielectric elastomers studied at a room temperature in terms of the electrical yield strength, the bending angle, the generated dielectrophoresis force, the energy density, the force density, the mechanical power, the power density, Ǵ at 1 rad/s at 0.25% strain, and the relatively high ɛ́r,20Hz.
Source: Sensors and Actuators A: Physical, Available online 29 December 2011
Wissawin Kunchornsup, Anuvat Sirivat
Cellulose shows promising piezoelectric properties widely used in electroactive papers (EAPaps), however its solubility still remains a challenging problem. 1-Butyl-3-methylimidazolium Chloride (BMIMCl), a well-known room temperature ionic liquid (RTIL), is utilized here to dissolve a micro-crystalline cellulose. The BMIMCl- cellulose gels are prepared by the solvent casting method. The elctromechanical properties of the cellulose gels are investigated under the oscillatory shear mode at electric field strengths between 0 to 1 kV/mm and as functions of temperature. The storage modulus (Ǵ) increases linearly with temperature up to 333 K at 1 rad/s in the absence of electric field strength. The storage moduli (Ǵ) also increase linearly with temperature up to 313 K at 1 rad/s in the presence of 1 kV/mm of electric field strength and decreases above 313 K, consistent with the behavior of dielectric permittivity (ɛ́). The elastic-plastic-viscous transition is observed in the presence of 1 kV/mm. It is shown that the conditions imposed by electric field strength and temperature alter the transition temperature, and lower the dielectric constant, the storage modulus, and the actuation performance. In the deflection experiments, under applied DC electric field, the deflection distances of the gels linearly increase with increasing electric field strength along with the dielectrophoresis forces above the electrical yield strength of 100 V/mm. The back and forth swinging occurs under the constant electric field strength between 525-550 V/mm due to the competition between the anion and cation movements within the ionic liquid. Electrostatic force microscope (EFM) is then employed to investigate the gel topology and the cationic channel and aggregation that control the actuation behavior. The Phy gel is shown here to be promising for actuator applications over other existing dielectric elastomers studied at a room temperature in terms of the electrical yield strength, the bending angle, the generated dielectrophoresis force, the energy density, the force density, the mechanical power, the power density, Ǵ at 1 rad/s at 0.25% strain, and the relatively high ɛ́r,20Hz.
Fabrication of Submicron-gap Electrodes by Silicon Volume Expansion for DNA-Detection
30 December 2011, 02:38:01
Publication year: 2011
Source: Sensors and Actuators A: Physical, Available online 29 December 2011
Xuejiao Chen, Jian Zhang, Zhiliang Wang, Qiang Yan
In this paper, submicron-gap electrodes were fabricated by traditional IC technology. The principle involved is based on the silicon volume expansion in the transition from silicon (Si) to silicon dioxide (SiO2) during thermal oxidation. The micron-level silicon electrode gaps were first generated on the silicon wafer by the conventional photolithography followed by deep reactive ion etching process. The thermal oxidation was then conducted to induce silicon volume expansion. As a result, the gap distance can decrease from micron level to submicron or even nanometer level, which depends on the oxidation parameters. Subsequently, the electrical DNA sensor, which can detect theI-Vvariations during DNA hybridization, had been constructed with the interdigitated submicron-gap electrodes. The result shows that the sensitivity of as-fabricated electrodes with 600 nm gap width can reach 2.5 μA/nM. This method may enable the batch-production and low-cost DNA biosensors.
Source: Sensors and Actuators A: Physical, Available online 29 December 2011
Xuejiao Chen, Jian Zhang, Zhiliang Wang, Qiang Yan
In this paper, submicron-gap electrodes were fabricated by traditional IC technology. The principle involved is based on the silicon volume expansion in the transition from silicon (Si) to silicon dioxide (SiO2) during thermal oxidation. The micron-level silicon electrode gaps were first generated on the silicon wafer by the conventional photolithography followed by deep reactive ion etching process. The thermal oxidation was then conducted to induce silicon volume expansion. As a result, the gap distance can decrease from micron level to submicron or even nanometer level, which depends on the oxidation parameters. Subsequently, the electrical DNA sensor, which can detect theI-Vvariations during DNA hybridization, had been constructed with the interdigitated submicron-gap electrodes. The result shows that the sensitivity of as-fabricated electrodes with 600 nm gap width can reach 2.5 μA/nM. This method may enable the batch-production and low-cost DNA biosensors.
Highlights
► The electrodes were fabricated by thermal oxidization and traditional IC process. ► The design concept is to realize submicron-level fabrication by micron-level technology. ► The fabrication technology is simple, reproducible, ingenious, low-cost, high-yield. ► The method can avoid the limitation of lithography and rigorous fabrication condition. ► The as-prepared submicron-gap electrodes have potential for bio-electronic devices.Power Enhancement of Micro Thermoelectric Generators by Microfluidic Heat Transfer Packaging
30 December 2011, 02:38:01
Publication year: 2011
Source: Sensors and Actuators A: Physical, Available online 29 December 2011
N. Wojtas, E. Schwyter, W. Glatz, S. Kühne, W.Escher, ...
This paper reports on the design, fabrication and proof of concept of a multilayer fluidic packaging system enabling an increase in the output power performance of micro thermoelectric generators (μTEGs). The complete integration of the microfluidic heat transfer system (μHTS) with a μTEG is successfully demonstrated.The fabricated prototype is characterized with respect to its thermal and hydrodynamic performance as well as the generated output power. At a very low pumping power of 0.073mW/cm, a heat transfer resistance of 0.74 cmK/W is reached. The assembled device generated up to 1.47mW/cmat an applied temperature difference of 50 K and a fluid flow rate of 0.1l/min. Further system improvements and the potential of the proposed packaging approach are discussed.
Source: Sensors and Actuators A: Physical, Available online 29 December 2011
N. Wojtas, E. Schwyter, W. Glatz, S. Kühne, W.Escher, ...
This paper reports on the design, fabrication and proof of concept of a multilayer fluidic packaging system enabling an increase in the output power performance of micro thermoelectric generators (μTEGs). The complete integration of the microfluidic heat transfer system (μHTS) with a μTEG is successfully demonstrated.The fabricated prototype is characterized with respect to its thermal and hydrodynamic performance as well as the generated output power. At a very low pumping power of 0.073mW/cm, a heat transfer resistance of 0.74 cmK/W is reached. The assembled device generated up to 1.47mW/cmat an applied temperature difference of 50 K and a fluid flow rate of 0.1l/min. Further system improvements and the potential of the proposed packaging approach are discussed.
Tuesday, 3 January 2012
Just Published: Journal of Chromatography B
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:
Selected papers from the latest issue:
Gas chromatographic-mass spectrometric investigation of volatile and extractable compounds of crude royal jelly
31 December 2011, 21:55:15
Publication year: 2011
Source: Journal of Chromatography B, Available online 30 December 2011
V.A. Isidorov, S. Bakier, I. Grzech
Using headspace solid-phase microextraction (HS-SPME) followed by diethyl ether and methanol extraction, it was possible to isolate as many as 185 organic compounds out of 17 samples of crude royal jelly (RJ). Of the above compound number, 169 compounds were positively identified by means of gas chromatography–mass spectrometry. The volatile fraction of RJ consists of 25 different compounds where approximately 47% of the total ion current (TIC) of volatile compound chromatograms were composed of substances characterized by bactericidal (phenols) and repelling (octanoic acid and 2-heptanone) activities. Preliminary investigations have shown that RJ stored for 10 months at -18 °C and 4 °C keeps its composition of volatile compounds unchanged, however, at the same time at room temperature RJ phenol contents is decreased twice, whereas the fraction of aliphatic acids is increased 2.8 times due to the presence of both acetic and butyric acids. The chromatogram of RJ ether extracts showed 85 different compounds, however about 88% of TIC consisted exclusively of 8 compounds, i.e. 10-hydroxy-2-decenoic, 10-hydroxydecanoic, 3,10-dihydroxydecanoic, 8-hydroxyoctanoic, 2-decene-1,10-dioc and (Z)-9-hydroxy-2-decenoic acids. Nine aliphatic acids, which were detected for the first time, are the homologues of hydroxy- and oxo-acids identified earlier in RJ. In the RJ methanol extracts 82 compounds were identified, mainly carbohydrates and their derivatives. Approximately 87% of TIC consisted of fructose, glucose and sucrose. Special attention was paid to discrepancies between obtained and literature data concerning the presence of free amino acids in RJ. It was suggested that these inconsistencies can be explained by the differences in the methods of RJ collection and/or sample preparation.
Source: Journal of Chromatography B, Available online 30 December 2011
V.A. Isidorov, S. Bakier, I. Grzech
Using headspace solid-phase microextraction (HS-SPME) followed by diethyl ether and methanol extraction, it was possible to isolate as many as 185 organic compounds out of 17 samples of crude royal jelly (RJ). Of the above compound number, 169 compounds were positively identified by means of gas chromatography–mass spectrometry. The volatile fraction of RJ consists of 25 different compounds where approximately 47% of the total ion current (TIC) of volatile compound chromatograms were composed of substances characterized by bactericidal (phenols) and repelling (octanoic acid and 2-heptanone) activities. Preliminary investigations have shown that RJ stored for 10 months at -18 °C and 4 °C keeps its composition of volatile compounds unchanged, however, at the same time at room temperature RJ phenol contents is decreased twice, whereas the fraction of aliphatic acids is increased 2.8 times due to the presence of both acetic and butyric acids. The chromatogram of RJ ether extracts showed 85 different compounds, however about 88% of TIC consisted exclusively of 8 compounds, i.e. 10-hydroxy-2-decenoic, 10-hydroxydecanoic, 3,10-dihydroxydecanoic, 8-hydroxyoctanoic, 2-decene-1,10-dioc and (Z)-9-hydroxy-2-decenoic acids. Nine aliphatic acids, which were detected for the first time, are the homologues of hydroxy- and oxo-acids identified earlier in RJ. In the RJ methanol extracts 82 compounds were identified, mainly carbohydrates and their derivatives. Approximately 87% of TIC consisted of fructose, glucose and sucrose. Special attention was paid to discrepancies between obtained and literature data concerning the presence of free amino acids in RJ. It was suggested that these inconsistencies can be explained by the differences in the methods of RJ collection and/or sample preparation.
Highlights
► Volatile compounds of fresh royal jelly ► bactericidal and repelling activities ► markers of inappropriate storage ► extractable compounds of royal jelly ► possible source of free amino acids.Determination of atomoxetine metabolites in human plasma by liquid chromatography/tandem mass spectrometry and its application to a pharmacokinetic study
31 December 2011, 21:55:15
Publication year: 2011
Source: Journal of Chromatography B, Available online 30 December 2011
Chang-Ik Choi, Jung-Woo Bae, Hye-In Lee, Choon-Gon Jang, Uy Dong Sohn, ...
4-Hydroxyatomoxetine (4-HAT) andN-desmethylatomoxetine (N-DAT) are major metabolites of atomoxetine, a potent and selective inhibitor of the presynaptic norepinephrine transporter that is used for the treatment of attention deficit/hyperactivity disorder. The pharmacological activity of 4-HAT is similar to that of atomoxetine. We have developed and validated a simple, rapid and sensitive liquid chromatography analytical method with tandem mass spectrometry (LC-MS/MS) for the determination of 4-HAT and N-DAT in human plasma. After liquid-liquid extraction with methylt-butyl ether, chromatographic separation of analytes was performed using a reversed-phase Luna C18column (2.0 mm × 100 mm, 3 μm particles) with a mobile phase of 10 mM ammonium formate buffer (pH 3.5)-methanol (10:90, v/v) and quantified by MS/MS detection in ESI positive ion mode. The flow rate of the mobile phase was 250 μL/min and the retention times of 4-HAT, N-DAT and internal standard (IS, metoprolol) were 0.9, 1.0 and 1.0 min, respectively. The calibration curves were linear over the range of 0.05-20 ng/mL for 4-HAT and 0.1-20 ng/mL for N-DAT. The lower limits of quantification, using 200 μL human plasma, were 0.05 and 0.1 ng/mL for 4-HAT and N-DAT, respectively. The mean accuracy and precision for intra- and inter-day validation of 4-HAT and N-DAT were both within the acceptable limits. This LC-MS/MS method showed improved sensitivity for quantification of the two main metabolites of atomoxetine in human plasma compared with previously described analytical methods. The validated method was successfully applied to a pharmacokinetic study in humans.
Source: Journal of Chromatography B, Available online 30 December 2011
Chang-Ik Choi, Jung-Woo Bae, Hye-In Lee, Choon-Gon Jang, Uy Dong Sohn, ...
4-Hydroxyatomoxetine (4-HAT) andN-desmethylatomoxetine (N-DAT) are major metabolites of atomoxetine, a potent and selective inhibitor of the presynaptic norepinephrine transporter that is used for the treatment of attention deficit/hyperactivity disorder. The pharmacological activity of 4-HAT is similar to that of atomoxetine. We have developed and validated a simple, rapid and sensitive liquid chromatography analytical method with tandem mass spectrometry (LC-MS/MS) for the determination of 4-HAT and N-DAT in human plasma. After liquid-liquid extraction with methylt-butyl ether, chromatographic separation of analytes was performed using a reversed-phase Luna C18column (2.0 mm × 100 mm, 3 μm particles) with a mobile phase of 10 mM ammonium formate buffer (pH 3.5)-methanol (10:90, v/v) and quantified by MS/MS detection in ESI positive ion mode. The flow rate of the mobile phase was 250 μL/min and the retention times of 4-HAT, N-DAT and internal standard (IS, metoprolol) were 0.9, 1.0 and 1.0 min, respectively. The calibration curves were linear over the range of 0.05-20 ng/mL for 4-HAT and 0.1-20 ng/mL for N-DAT. The lower limits of quantification, using 200 μL human plasma, were 0.05 and 0.1 ng/mL for 4-HAT and N-DAT, respectively. The mean accuracy and precision for intra- and inter-day validation of 4-HAT and N-DAT were both within the acceptable limits. This LC-MS/MS method showed improved sensitivity for quantification of the two main metabolites of atomoxetine in human plasma compared with previously described analytical methods. The validated method was successfully applied to a pharmacokinetic study in humans.
Highlights
► A sensitive LC-MS/MS assay method for two metabolites of atomoxetine was developed. ► LLOQ was 0.05 ng/mL for 4-hydroxyatomoxetine and 0.1 ng/mL forN-desmethylatomoxetine. ► The validated method was successfully applied to a pharmacokinetic study in humans.Determination of landiolol, an ultra-short-acting β1-receptor antagonist, in human plasma by liquid chromatography-tandem mass spectrometry
31 December 2011, 21:55:15
Publication year: 2011
Source: Journal of Chromatography B, Available online 30 December 2011
Qun He, Meiyun Shi, Xidong Liu, Yantong Sun, Lianghai Hu, ...
A method for the determination of landiolol, an ultra-short-acting β1-adrenoreceptor antagonist, in human plasma has been developed and validated. With the addition of pyridostigmine bromide to stabilize landiolol in the blood/plasma samples, and bisoprolol as internal standard, plasma samples were subjected to liquid-liquid extraction with diethyl ether:dicholoromethane (60:40, v/v) prior to assay by liquid chromatography-tandem mass spectrometry. Separation was performed on a TC-C18column (150 × 4.6 mm, 5 μm) using a mobile phase of methanol:10 mM ammonium acetate containing 1% formic acid (65:35, v/v) in a run time of 3.5 min. Detection involved electrospray ionization in the positive ion mode followed by multiple reaction monitoring of the precursor-to-product ion transitions of landiolol atm/z510.1→157.2 and bisoprolol atm/z326.3→116.1. The method was linear over the concentration range 0.5-500 ng/ml with a lower limit of quantitation of 0.5 ng/ml. Intra- and inter-day precisions (as relative standard deviation, RSD) were < 4.4% and < 10.0%, respectively, with accuracy (as relative error, RE) < 10.0%. The method was successfully applied to a clinical pharmacokinetic study involving a continuous infusion of landiolol hydrochloride to healthy Chinese volunteers.
Source: Journal of Chromatography B, Available online 30 December 2011
Qun He, Meiyun Shi, Xidong Liu, Yantong Sun, Lianghai Hu, ...
A method for the determination of landiolol, an ultra-short-acting β1-adrenoreceptor antagonist, in human plasma has been developed and validated. With the addition of pyridostigmine bromide to stabilize landiolol in the blood/plasma samples, and bisoprolol as internal standard, plasma samples were subjected to liquid-liquid extraction with diethyl ether:dicholoromethane (60:40, v/v) prior to assay by liquid chromatography-tandem mass spectrometry. Separation was performed on a TC-C18column (150 × 4.6 mm, 5 μm) using a mobile phase of methanol:10 mM ammonium acetate containing 1% formic acid (65:35, v/v) in a run time of 3.5 min. Detection involved electrospray ionization in the positive ion mode followed by multiple reaction monitoring of the precursor-to-product ion transitions of landiolol atm/z510.1→157.2 and bisoprolol atm/z326.3→116.1. The method was linear over the concentration range 0.5-500 ng/ml with a lower limit of quantitation of 0.5 ng/ml. Intra- and inter-day precisions (as relative standard deviation, RSD) were < 4.4% and < 10.0%, respectively, with accuracy (as relative error, RE) < 10.0%. The method was successfully applied to a clinical pharmacokinetic study involving a continuous infusion of landiolol hydrochloride to healthy Chinese volunteers.
Highlights
► A novel method for determination of landiolol in plasma by LC-MS/MS was developed. ► Landiolol in blood/plasma samples is stabilized by pyridostigmine bromide. ► The plasma samples were prepared by liquid-liquid extraction. ► The LLOQ of the method is 0.5 ng/ml which is the lowest reported so far. ► The method was successfully applied to a clinical pharmacokinetic study of landiolol.DEVELOPMENT AND OPTIMIZATION OF SIMPLIFIED LC-MS/MS QUANTIFICATION OF 25-HYDROXYVITAMIN D USING PROTEIN PRECIPITATION COMBINED WITH ON-LINE SOLID PHASE EXTRACTION (SPE)
27 December 2011, 23:59:53
Publication year: 2011
Source: Journal of Chromatography B, Available online 27 December 2011
Denis Thibeault, Nicolas Caron, Rose Djiana, Richard Kremer, David Blank
25-hydroxyvitamin D, the most useful marker of the vitamin D status of an individual, has seen an exponential growth of its routine measurement in recent years. Several methods are currently offered but the most specific is LC-MS/MS. However, the routine use of this technique in the clinical laboratory makes it essential to improve key steps of this method for high throughput delivery. Importantly, the preanalytical steps of this assay and the efficacy of the separation system need to be optimized prior to MS detection. In this report we replaced the standard and time consuming liquid-liquid extraction method of vitamin D metabolites with hexane (LLE) combined with centrifugation (LLE/centrifugation) by a simpler protein precipitation with extraction (PPE) in acetonitrile combined with a fast separation process using a 96-well plate filtration system (PPE/filtration). This rapid extraction was then followed by an on-line solid phase extraction (SPE) using a selective chromatographic separation. We also optimized the operational and consumable costs, by using an inexpensive guard column as a trapping column to significantly enhance the lifespan of the analytical column 2-3 times as compared to conventional chromatography. The LC-MS/MS technique permits the measurement of both 25-hydroxyvitaminD2(25-OH D2)and the 25-hydroxyvitaminD3(25-OH D3) metabolites in electrospray ionization (ESI) mode. The chromatographic system consisted of a 2.1 × 50 mm C18 3.5 μM column with a 2.1 × 20 mm C18 3.5 μM guard column connected with two 6 ports switching valves. Quantifications were done using the isotopic dilution technique with hexadeutered 25-OH D3and 25-OH D2.The ion suppression problem with phospholipids was also evaluated and optimized to minimize this effect through the chromatography process and the on-line SPE trapping. Calibration curves were prepared by diluting a commercial high calibrator Chromsystems (München, Germany) with either pure triple stripped blank serum or diluted in 6% phosphate buffer saline at pH 7.2. Linearity was tested up to 160 nmol/L for 25-OH D3and 75 nmol/L for 25-OH D2. Low limit of quantification (LLOQ) were established at 3 nmol/L for 25-OH D2and 4 nmol/L for 25-OH D3. Inter-assay and intra-assay precision (CV%) was determined using 3 levels of commercial controls (Utak, CA 91355, USA) for 25-OH D2and 25-OH D3. Results obtained for intra-assay and inter-assay precision (CV%) were 1.1 to 3.4% and 5 to 8.9% respectively for the PPE/centrifugation technique and 2.0 to 3.1% and 4.6 to 6.6% for the PPE/filtration technique. Accuracy was estimated with the same commercial controls: % bias was -11.2 to 4.9% with PPE/centrifugation and -3.2-6.1% with PPE/filtration. 25-OH D2and 25-OH D3concentrations in human serum with LLE were compared to the new extraction methods using either PPE/centrifugation or PPE/filtration. Correlations comparing the two methods revealed a slope approximately 1.0 ± 0.3 with R ≥ 0.98 with a bias < 1 nmol/L. In summary, the new LC-MS/MS method described in this report using an on-line SPE technique with a simple off-line pre-treatment is faster, cost-effective, more reliable and more robust than current and widely used LLE/centrifugation methods coupled with LC-MS/MS.
Source: Journal of Chromatography B, Available online 27 December 2011
Denis Thibeault, Nicolas Caron, Rose Djiana, Richard Kremer, David Blank
25-hydroxyvitamin D, the most useful marker of the vitamin D status of an individual, has seen an exponential growth of its routine measurement in recent years. Several methods are currently offered but the most specific is LC-MS/MS. However, the routine use of this technique in the clinical laboratory makes it essential to improve key steps of this method for high throughput delivery. Importantly, the preanalytical steps of this assay and the efficacy of the separation system need to be optimized prior to MS detection. In this report we replaced the standard and time consuming liquid-liquid extraction method of vitamin D metabolites with hexane (LLE) combined with centrifugation (LLE/centrifugation) by a simpler protein precipitation with extraction (PPE) in acetonitrile combined with a fast separation process using a 96-well plate filtration system (PPE/filtration). This rapid extraction was then followed by an on-line solid phase extraction (SPE) using a selective chromatographic separation. We also optimized the operational and consumable costs, by using an inexpensive guard column as a trapping column to significantly enhance the lifespan of the analytical column 2-3 times as compared to conventional chromatography. The LC-MS/MS technique permits the measurement of both 25-hydroxyvitaminD2(25-OH D2)and the 25-hydroxyvitaminD3(25-OH D3) metabolites in electrospray ionization (ESI) mode. The chromatographic system consisted of a 2.1 × 50 mm C18 3.5 μM column with a 2.1 × 20 mm C18 3.5 μM guard column connected with two 6 ports switching valves. Quantifications were done using the isotopic dilution technique with hexadeutered 25-OH D3and 25-OH D2.The ion suppression problem with phospholipids was also evaluated and optimized to minimize this effect through the chromatography process and the on-line SPE trapping. Calibration curves were prepared by diluting a commercial high calibrator Chromsystems (München, Germany) with either pure triple stripped blank serum or diluted in 6% phosphate buffer saline at pH 7.2. Linearity was tested up to 160 nmol/L for 25-OH D3and 75 nmol/L for 25-OH D2. Low limit of quantification (LLOQ) were established at 3 nmol/L for 25-OH D2and 4 nmol/L for 25-OH D3. Inter-assay and intra-assay precision (CV%) was determined using 3 levels of commercial controls (Utak, CA 91355, USA) for 25-OH D2and 25-OH D3. Results obtained for intra-assay and inter-assay precision (CV%) were 1.1 to 3.4% and 5 to 8.9% respectively for the PPE/centrifugation technique and 2.0 to 3.1% and 4.6 to 6.6% for the PPE/filtration technique. Accuracy was estimated with the same commercial controls: % bias was -11.2 to 4.9% with PPE/centrifugation and -3.2-6.1% with PPE/filtration. 25-OH D2and 25-OH D3concentrations in human serum with LLE were compared to the new extraction methods using either PPE/centrifugation or PPE/filtration. Correlations comparing the two methods revealed a slope approximately 1.0 ± 0.3 with R ≥ 0.98 with a bias < 1 nmol/L. In summary, the new LC-MS/MS method described in this report using an on-line SPE technique with a simple off-line pre-treatment is faster, cost-effective, more reliable and more robust than current and widely used LLE/centrifugation methods coupled with LC-MS/MS.
Thermo Fisher Scientific Names Winner of 2012 Winter Conference Award in Plasma Spectrochemistry
Submissions now being accepted for 2014 award
Thermo Fisher Scientific Inc., the world leader in serving science, has announced the winner of the 2012 Winter Conference Award in Plasma Spectrochemistry, Dr. J. Sabine Becker, head of Trace and UltraTrace Analysis, Central Division of Analytical Chemistry at the Research Center Juelich, Germany. The award, which honors scientists who have made the most noteworthy contributions to the field of plasma spectrochemistry, is sponsored by Thermo Fisher. Thermo Fisher will present the award and a check for $5,000 to Dr. Becker during the 2012 Winter Conference on Plasma Spectrochemistry to be held in Tucson, Ariz. January 9–14, 2012.
Dr. Becker’s distinguished career in analytical chemistry has focused on long-lived radionuclides, ultratrace and high-purity materials analysis, isotope ratio measurements, and micro and nanolocal elemental and trace analyses. Recently she established BrainMet, an Analytical Center of Excellence at the Research Centre Juelich for brain research imaging. Based on laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), BrainMet has introduced novel imaging techniques for metals, metalloids and non-metals in biological tissues. The approach provides quantitative mapping of essential and toxic elements in thin sections of diseased and healthy medical and biological tissue sections.
“As the leader in plasma spectrochemistry instrumentation, Thermo Fisher is pleased to sponsor an industry award that brings together the major figures in this field,” said Lothar Rottmann, global support manager, inorganic mass spectrometry at Thermo Fisher. “The Winter Conference award complements our objectives for advancement and innovation, and we look forward to honoring Dr. Becker for her remarkable achievements in this field.”
The Winter Conference Award in Plasma Spectrochemistry, established in 2009, is sponsored by Thermo Fisher to recognize scientists who have made noteworthy contributions over time or through a single, significant breakthrough. The award acknowledges achievements in conceptualization and development of novel instrumentation as well as the elucidation of fundamental events or processes involved in plasma spectrochemistry. Winners include authors of significant research papers or books that influence new advancements or pioneers of outstanding new applications that benefit the field of plasma spectrochemistry.
The Winter Conference on Plasma Spectrochemistry brings together international scientists experienced in applications, instrumentation and theory in an informal setting to examine recent progress in the field. The 2012 conference will feature developments in plasma spectrochemical analysis by inductively coupled plasma (ICP), dc plasma (DCP), microwave plasma (MIP), glow discharge (GDL, HCL) and laser sources.
Entry is now open for the next Winter Plasma Award in 2014 and Thermo Fisher invites scientists worldwide to submit their applications. Candidates should send their application with CV to wpc.award@thermofisher.com by December 31 2012. The award is judged by an independent award committee consisting of seven internationally recognized spectrochemical experts, including the previous award recipient. For further information, details, terms and conditions, please visit www.thermoscientific.com/wpcaward.
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