World Congress on Biosensors 2014

World Congress on Biosensors 2014
Biosensors 2014

Wednesday 31 July 2013

Just Published: Talanta

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:
Talanta

Selected papers from the latest issue:

Stir bar sorptive extraction coupled to liquid chromatography-tandem mass spectrometry for the determination of pesticides in water samples: Method validation and measurement uncertainty

31 July 2013, 09:53:11
Publication date: 15 November 2013
Source:Talanta, Volume 116
Author(s): Christelle Margoum , Céline Guillemain , Xi Yang , Marina Coquery
Stir bar sorptive extraction followed by liquid desorption and high performance liquid chromatography with tandem mass spectrometry (SBSE-LD-LC-MSMS) has been developed for the determination of 15 pesticides or selected metabolites from different families (herbicides, insecticides, fungicides) in surface water samples. The optimization of parameters that could influence SBSE-LD efficiency was carried out by means of experimental design. Optimized conditions were established as follows concerning extraction time, stirring speed, aqueous medium characteristics (ionic strength and polarity) and back desorption solvent and time, respectively: 3h (800rpm), addition of 10% of sodium chloride, no addition of methanol as organic modifier, and 15min ultrasonic desorption in equivolume mixtures of acetonitrile-methanol. A specific and thorough cleanup procedure was developed and applied to each stir bar to avoid possible carry-over between consecutive extractions with the same stir bar. Pesticide quantification in water was achieved thanks to matrix matched calibration. Mean recoveries ranged from 93 to 101% (RSD <17%, n=30). Validated limits of quantification in matrix were between 0.02 and 1µgL−1, depending on the compound. A specific experimental design was conducted to evaluate the measurement uncertainty, which was comprised between 13 and 51%, whatever the pesticide and the concentration level. The applicability of the SBSE-LD-LCMSMS method was evaluated by analyzing surface water samples and by comparing with conventional solid phase extraction-LC-MSMS procedure.

Graphical abstract

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Investigating of labelling and detection of transthyretin synthetic peptide derivatized with naphthalene-2,3-dicarboxaldehyde

31 July 2013, 09:53:11
Publication date: 15 November 2013
Source:Talanta, Volume 116
Author(s): Mathilde Faure , Sonia Korchane , Isabelle Le Potier , Antoine Pallandre , Claude Deslouis , Anne-Marie Haghiri-Gosnet , Jean Gamby
Labelling and detection of a synthetic peptide (PN) mimicking a tryptic fragment of interest for the diagnosis of familial amyloidal polyneuropathy have been investigated optically and electrochemically. We decided to covalently label naphtalene-2,3-dicarboxyaldehyde (NDA), a fluorogenic and electroactive molecule on PN. First, the optimization of the labelling chemical reaction was performed by capillary electrophoresis coupled with laser induced fluorescence detection (CE-LIF). The analytical parameters such as separation efficiency and peak area were considered to propose this optimized derivatization reaction. The results obtained allowed us to establish the pH and ionic strength of the derivatization buffer, the molar ratio between NDA and PN and the reaction time of the labelling. Optimal conditions are obtained when [NDA]/[PN]=40, buffer pH of 9, buffer ionic strength of 70mM and reaction time of 15min. Second, differential pulse voltammetry (DPV) and cyclic voltammetry (CV) were also used to characterize NDA-labelled PN and different electroinactive amino acids (histidine, lysine, serine, threonine) which are in the PN sequence. The electrochemical detection experiments demonstrated that the labelled biomolecules could be also easily detected at low concentration. Moreover, the derivatization reaction could be followed to describe more precisely the labelling process of these biomolecules. Optimal conditions for labelling are obtained when [NDA]total/[CN-] ratio =1 and [NDA]total/[amino acid or peptide]=100 with a buffer having a pH=9 on a glassy carbon electrode. In all cases, an obvious oxidation peak for the N-2-substituted-1-cyanobenz-[f]-isoindole derivative (CBI) has been observed at 0.5–0.7V/SCE. The multi-labelling of PN and lysine were shown with DPV. We presumed this result to occur because of the shouldered shape of the DPV peak shape. These experiments confirm that NDA can be used as a derivative agent for PN, allowing for electrochemical and fluorescence detections with a limit of detection of labelled PN estimated at 0.2µM and 5µM, respectively.

Surface-enhanced Raman spectroscopy detection of polybrominated diphenylethers using a portable Raman spectrometer

31 July 2013, 09:53:11
Publication date: 15 November 2013
Source:Talanta, Volume 116
Author(s): Xiaohong Jiang , Yongchao Lai , Wei Wang , Wei Jiang , Jinhua Zhan
Polybrominated diphenylethers (PBDEs), one of the most common brominated flame retardants, are toxic and persistent, generally detected by the chromatographic method. In this work, qualitative and quantitative detection of PBDEs were explored based on surface-enhanced Raman spectroscopy (SERS) technique using a portable Raman spectrometer. Alkanethiol modified silver nanoparticle aggregates were used as the substrate and PBDEs could be pre-concentrated close to the substrate surface through their hydrophobic interactions with alkanethiol. The effect of alkanethiols with different chain length on the SERS detection of PBDEs was evaluated. It was shown that 1-hexanethiol (HT) modified substrate has higher sensitivity, good stability and reusability. Qualitative and quantitative SERS detection of PBDEs in real sea water was accomplished, with the measured detection limits at 1.2×102 μgL−1. These results illustrate SERS could be used as an effective method for the detection of PBDEs.

Determination of trace level cadmium in SRM 3280 Multivitamin/Multielement Tablets via isotope dilution inductively coupled plasma mass spectrometry

31 July 2013, 09:53:11
Publication date: 15 November 2013
Source:Talanta, Volume 116
Author(s): Steven J. Christopher , Robert Q. Thompson
Cadmium was quantified at 80.15±0.86ng/g (mean±95% expanded uncertainty) in NIST SRM 3280 Multivitamin/Multielement Tablets, using isotope dilution mass spectrometry. The method described utilized various precipitation and solid-phase extraction separation methodologies to isolate Cd from Sn and Mo, present respectively, at 11.1±0.9mg/kg and 70.7±4.5mg/kg in the tablet matrix. This allowed for measurement of 111Cd/113Cd and 111Cd/114Cd isotope ratios using both quadrupole collision cell technology inductively coupled plasma mass spectrometry (Q-CCT-ICP-MS) and sector field (SF)-ICP-MS equipped with a desolvating nebulizer system to mitigate the MoO+ and MoOH+ molecular ion interferences that typically affect the envelope of Cd isotopes.

On-chip electrochemical microsystems for measurements of copper and conductivity in artificial seawater

31 July 2013, 09:53:11
Publication date: 15 November 2013
Source:Talanta, Volume 116
Author(s): Grégoire Herzog , Waleed Moujahid , Karen Twomey , Conor Lyons , Vladimir I. Ogurtsov
The fabrication and characterisation of microelectrochemical sensors for Cu2+ and conductivity suitable for operation in the marine environment are presented. The impact of the designs on sensor performance and their adequacy to operate in real conditions are discussed. The sensors, tailored to voltammetric and impedimetric measurements, are fabricated on silicon using photolithographic and thin film deposition techniques. The impedimetric sensor is made of Pt interdigitated electrodes which are used for the measurement of conductivity. The voltammetric sensors are based on a three electrode electrochemical cell with on-chip Ag|AgCl reference and Pt counter and working electrodes, used for detection of copper by underpotential deposition-stripping voltammetry at microelectrode array. The sensors operated in the Cu2+ concentrations ranging from 0.48 to 3.97µM with a limit of detection of 0.115μM. The impact of the temperature, the pH and the salinity of the artificial seawater on the sensitivity for Cu2+ detection are also considered. Measurements of copper concentration and conductivity are validated using certified reference materials and standard solutions.

Detection of chemical residues in tangerine juices by a duplex immunoassay

31 July 2013, 09:53:11
Publication date: 15 November 2013
Source:Talanta, Volume 116
Author(s): P. Navarro , A.J. Pérez , J.A. Gabaldón , E. Núñez-Delicado , R. Puchades , A. Maquieira , S. Morais
A rapid duplex ELISA for the simultaneous determination of two of the most widely used organophosphorous insecticides in tangerine juices is described. To accomplish this aim, two individual enzyme-linked immunosorbent assays for chlorpyrifos and fenthion pesticides were integrated into one ELISA test. The strategy uses 96-well plates with specific wells coated with the corresponding haptenized conjugate. The optimized duplex ELISA was accomplished within 40min achieving a detection limit of 0.20±0.04µg/L and 0.50±0.06µg/L, for chlorpyrifos and fenthion, respectively in tangerine juice samples. The determination of residues of both pesticides was carried out by simple sample dilution, without any extra sample clean-up procedure. Results of testing precision, stability, and selectivity demonstrated that the assay provided reliable analytical performances for the simultaneous determination of residues of chlorpyrifos and fenthion in fruit juice samples below the established European maximum residue limits (MRL). In addition, the accuracy and reliability of this duplex bioanalytical method is demonstrated by analyzing blind spiked juice samples and the results, correlated well with those achieved using a well-established GC/MS method (recoveries between 95% and 106%).

Graphical abstract

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Semiautomated solid-phase extraction manifold with a solvent-level sensor

31 July 2013, 09:53:11
Publication date: 15 November 2013
Source:Talanta, Volume 116
Author(s): R.M. Orlando , S. Rath , J.J.R. Rohwedder
A semiautomated solid-phase extraction manifold for multiple extractions is presented. The manifold utilizes commercial solid-phase syringe cartridges and automatically introduces and elutes all the solvents during the extraction, reducing the typical workload and stress of the analyst. The manifold consists of a peristaltic pump with solenoid valves in a flow circuit that contains transmissive photomicrosensors. The photomicrosensors were used to control the solvent dispenser and the solvent level inside the cartridge. As solvent-level sensors, the photomicrosensors determined the exact time the solvent reached the top frit to avoid sorbent drying and accurately perform the solvent exchange. The repeatability of the manifold to introduce a particular volume of solvent into the cartridges was measured, and the precisions were between 0.05 and 2.89% (RSD). To evaluate the manifold, the amount of two fluoroquinolones in a fortified blank milk sample was determined. The results of the intra- and inter-day precision of multiple extractions from the fortified milk samples resulted in precisions better than 9.0% (RSD) and confirmed that the arrangement of the semiautomated manifold could adequately be used in solid-phase extraction with commercial cartridges. 

CMA Microdialysis Releases New Syringe Pump

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Harvard Apparatus
84 October Hill Road
Holliston, Massachusetts 01746 USA
Toll Free: 800-272-2775
Phone: 508-893-8999
Fax: 508-429-5732
E-mail: bioscience@harvardapparatus.com
Web: www.harvardapparatus.com

FREE Virtual Issue from Journal of Chromatography B


As the Publisher proudly responsible for this journal, I’m delighted to make some of the highly cited papers openly available for the next 12 months. I had originally decided just to share some of the papers that had an impact from an historical perspective, but then added some more recent articles that have generated a great deal of interest.
Please share with your friends and colleagues working in this area.
David Sleeman
Publisher - Journal of Chromatography B
July 2013

Tuesday 30 July 2013

Just Published: Trends in Analytical Chemistry

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:

Emerging green technologies for the chemical standardization of botanicals and herbal preparations

30 July 2013, 08:44:08
Publication date: October 2013
Source:TrAC Trends in Analytical Chemistry, Volume 50
Author(s): Ming Yuan Heng , Swee Ngin Tan , Jean Wan Hong Yong , Eng Shi Ong
As botanicals and many medicinal plants can be processed to become a food or a health supplement, a drug or cosmetics, chemical standardization is important for their quality control. Hence, the selection of appropriate extraction technologies and analytical techniques is required to provide a solvent-free solution for the chemical standardization of botanicals and herbal preparations.

Multiple comparisons in mass-spectrometry-based -omics technologies

30 July 2013, 08:44:08
Publication date: October 2013
Source:TrAC Trends in Analytical Chemistry, Volume 50
Author(s): Pietro Franceschi , Marco Giordan , Ron Wehrens
Survey technologies, such as metabolomics and proteomics, play increasingly important roles in the investigation of complex biological systems. These methods produce data sets that typically provide a huge amount of information using relatively few samples, so that finding differences between two groups, a fairly common question in this context, runs the risk of leading to many false positives. Often, the comparison is made on several thousand experimental variables, and strategies to correct for multiple-testing issues are necessary. We highlight the most important ideas, and assess their applicability in the fields of mass-spectrometry-based proteomics and (especially) metabolomics.

Independent Components Analysis with the JADE algorithm

30 July 2013, 08:44:08
Publication date: October 2013
Source:TrAC Trends in Analytical Chemistry, Volume 50
Author(s): D.N. Rutledge , D. Jouan-Rimbaud Bouveresse
Independent Components Analysis (ICA) is a relatively recent method, with an increasing number of applications in chemometrics. Of the many algorithms available to compute ICA parameters, the Joint Approximate Diagonalization of Eigenmatrices (JADE) algorithm is presented here in detail. Three examples are used to illustrate its performance, and highlight the differences between ICA results and those of other methods, such as Principal Components Analysis. A comparison with Parallel Factor Analysis (PARAFAC) is also presented in the case of a three-way data set to show that ICA applied on an unfolded high-order array can give results comparable with those of PARAFAC.

Applications of metal-organic frameworks as stationary phases in chromatography

30 July 2013, 08:44:08
Publication date: October 2013
Source:TrAC Trends in Analytical Chemistry, Volume 50
Author(s): Yuebo Yu , Yuqian Ren , Wei Shen , Huimin Deng , Zhiqiang Gao
As a new family of mesoporous and microporous materials, metal-organic frameworks (MOFs) are considered versatile materials for widespread technical applications. We summarize some of the eminent properties of MOFs and the development in the application of MOFs in chromatography, especially the advantages they could bring to gas chromatography (GC) and high-performance liquid chromatography (HPLC). The application of MOFs as novel stationary phases in chromatography in place of conventional materials has led to notable improvements in the performance of GC and HPLC. We highlight differences in chromatographic performance between MOFs and conventional sorbents, such as zeolites, before discussing the future prospects for MOFs in chromatography.

Creatinine sensors

30 July 2013, 08:44:08
Publication date: October 2013
Source:TrAC Trends in Analytical Chemistry, Volume 50
Author(s): C.S. Pundir , Sandeep Yadav , Ashok Kumar
The measurement of creatinine level in human blood and urine is clinically essential, because it reflects the renal, muscular and thyroid functions. This article reviews the current status of electrochemical enzymic/non-enzymic and immunosensors for creatinine. The performance of creatinine sensors could be improved by tailoring the properties of the interface with nanoparticles through engineering morphology, particle size, effective surface area, functionality, adsorption capability and electron-transfer properties. We expect these interesting properties of nanomaterials to find applications in miniaturized, smart sensing devices.

Mass spectrometry as a useful tool for the analysis of stabilizers in polymer materials

30 July 2013, 08:44:08
Publication date: October 2013
Source:TrAC Trends in Analytical Chemistry, Volume 50
Author(s): Christian W. Klampfl
The potential of mass spectrometry (MS) for the analysis of stabilizers in plastics materials is reviewed, discussing the strong and weak points of the different techniques. Direct analysis of plastics samples without any, or with only minor, preparation steps is possible with MS techniques. Here, the primary focus lies in the fast identification of stabilizers in plastics, which is a useful tool for screening larger sets of samples. Also, the possibility of spatially-resolved surface analysis by MS is discussed.

Advances in the analysis of legal and illegal drugs in the aquatic environment

30 July 2013, 08:44:08
Publication date: October 2013
Source:TrAC Trends in Analytical Chemistry, Volume 50
Author(s): Pablo Vazquez-Roig , Cristina Blasco , Yolanda Picó
We review the current methods developed for the analysis of legal and illegal drugs (LIDs) and their metabolites in environmental samples. We discuss the advantages and the pitfalls of multi-class methods with emphasis on new strategies for sample preparation and recent technical developments. Finally, we present the applicability of these methods to the analysis of LIDs in protected environmental areas.

The 12 principles of green analytical chemistry and the SIGNIFICANCE mnemonic of green analytical practices

30 July 2013, 08:44:08
Publication date: October 2013
Source:TrAC Trends in Analytical Chemistry, Volume 50
Author(s): Agnieszka Gałuszka , Zdzisław Migaszewski , Jacek Namieśnik
The current rapid development of green analytical chemistry (GAC) requires clear, concise guidelines in the form of GAC principles that will be helpful in greening laboratory practices. The existing principles of green chemistry and green engineering need revision for their use in GAC because they do not fully meet the needs of analytical chemistry. In this article we propose a set of 12 principles consisting of known concepts (i.e. reduction in the use of reagents and energy, and elimination of waste, risk and hazard) together with some new ideas (i.e. the use of natural reagents), which will be important for the future of GAC.

Coagulation monitoring devices: Past, present, and future at the point of care

30 July 2013, 08:44:08
Publication date: October 2013
Source:TrAC Trends in Analytical Chemistry, Volume 50
Author(s): Leanne F. Harris , Vanessa Castro-López , Anthony J. Killard
Automated technologies have revolutionised the monitoring of coagulation disorders in the central hospital laboratory setting, allowing for high throughput testing, improved accuracy and precision, accompanied by a marked reduction in human error. However, they still require trained operators and sample transportation. With the advent of point of care (POC) testing, the working principle of traditional coagulometers was used as the foundation for the development of miniaturised devices. A number of POC coagulation devices have been commercially available for many years now, allowing the patient to assume more control over the management of their own medication, e.g. warfarin. While POC devices for measuring anticoagulation have relied principally on clotting time tests, novel platelet function tests, and factor-specific assays based on enzymatic or immunoassay principles are becoming available, driven by the emergence of new anticoagulant drugs, in addition to the inability of clotting tests to accurately detect many thrombotic disorders. This review highlights recent progress in the development of POC coagulation monitoring technologies and examines their future potential in clinical diagnostics. 

North American Microplate Catalog

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Featured for the first time is a new glass lined plate for UHPLC applications, more sterile plate options, the budget priced MicroSeal heat sealer and a next generation Miniseal II semi-automatic microplate sealer. Combining uncompromising high quality with an affordable price - Porvair Sciences offers an extensive range of deep well, shallow well, storage, assay, SPE and protein precipitation microplates. Precisely manufactured in a class 10000 cleanroom facility to comply with SLAS / ANSI dimensions ensures Porvair microplates are completely compatible with all automated sample handling systems, microplate readers and washers.

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To request a copy of the North American 2013 catalog please visit www.porvair-sciences.com/USA-Microplates or contact Porvair Sciences Ltd. now on int.sales@porvair-sciences.com.

Monday 29 July 2013

Just Published: Vibrational Spectroscopy

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:
Vibrational Spectroscopy

Selected papers from the latest issue:

Vibrational spectroscopic study of poly(dimethylsiloxane)-ZnO nanocomposites

29 July 2013, 09:01:11
Publication date: September 2013
Source:Vibrational Spectroscopy, Volume 68
Author(s): L. Bistričić , V. Borjanović , L. Mikac , V. Dananić
A series of poly(dimethylsiloxane)-zinc oxide (PDMS-ZnO) nanocomposites having different concentrations of ZnO nanoparticles (0, 1, 5, 10 and 20wt%) have been prepared. Raman and FTIR-ATR spectroscopic analysis was performed in order to determine the interaction between the ZnO nanoparticles and PDMS polymer matrix. Density functional theory (DFT) using the (B3-LYP)/6-311++G(2df,2p) method was used to investigate the vibrational spectra of PDMS. A complete vibrational assignment is supported by the normal coordinate analysis, calculated Raman activities as well as IR intensities. The presence of ZnO nanoparticles in PDMS gives rise to significant differences in relative intensities of the characteristic vibrational bands with respect to the cross-linked polymer. The changes in relative intensities of Raman bands, as well as swelling measurements, were used to explain the effect of ZnO nanoparticles on the cross-linked structure of PDMS nanocomposites. It is established that ZnO nanoparticles influence the cross-linking density of the polymer matrix.

Spectroscopic analysis of pigments and inks in manuscripts: I. Byzantine and post-Byzantine manuscripts (10–18th century)

29 July 2013, 09:01:11
Publication date: September 2013
Source:Vibrational Spectroscopy, Volume 68
Author(s): Irena Nastova , Orhideja Grupče , Biljana Minčeva-Šukarova , Melih Ozcatal , Lenče Mojsoska
Pigments and inks used in six Byzantine manuscripts (covering the period from 10th to 15th century) and one 18th century post-Byzantine manuscript have been analyzed, using micro-Raman spectroscopy, ATR-FT-infrared spectroscopy and SEM–EDS. Micro-Raman spectroscopy allowed fast and in situ analysis of majority of pigments and inks used, except for the purple-red organic pigment, brown-purple ink and metallic pigments (silver and gold). The nature of the organic purple-red pigment and organic purple ink was revealed applying ATR-FTIR. In the analysis of the metallic pigment (silver and gold) as well as additional technique in characterizing organic purple-red dye and ink, SEM–EDS was used. Varieties of inks were used in the manuscripts. Gold and silver inks were used for capital letters and for emphasizing certain paragraphs. Red ink was identified as madder in illuminated manuscripts and as vermilion in simple texts. Gall ink was identified as black-brown ink in most of the manuscripts. In 18th century manuscript logwood was identified while in the 12th century manuscript, goethite was used as ink. The analysis of the pigments and inks revealed that over the course of 5 centuries, the pigments used for decoration in Byzantine manuscripts remained similar and traditional (mineral and organic), with pronounced variations in the 18th century post-Byzantine manuscript.

Temperature dependence of the microstructure of 1-butyl-3-methylimidazolium tetrafluoroborate in aqueous solution

29 July 2013, 09:01:11
Publication date: September 2013
Source:Vibrational Spectroscopy, Volume 68
Author(s): Huiyong Wang , Jianji Wang , Lamei Zhang
Many applications of ionic liquids (ILs) are closely related with their microstructure in mixtures. For example, morphology and pore size of the MCM-41 prepared in aqueous ILs are greatly dependent on the aggregation behavior of the ILs in water. Therefore, the study on the microstructure of ILs in aqueous solutions is of great importance. In this work, 1H NMR, dynamic light scattering and attenuated total reflection infrared spectroscopy have been used to investigate the temperature effect on the structures of aqueous 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) solutions. It was shown that the size of the IL aggregates becomes larger with decreasing temperature. When the system temperature is below the upper critical solution temperature (UCST) of the binary mixture at about 4°C, the aggregate size of the IL is larger than 1000nm. Additionally, the two-dimensional IR results reveal that at low IL concentrations, H2O can interact with [BF4] prior to the CH groups of the imidazolium ring, whereas cation and anion of the IL tend to form aggregate at high IL concentrations. With the decrease of temperature, the interactions between cation and anion of the IL become stronger, but those between the IL and water become weaker, thereby resulting in the growth of the aggregate of cation with anion of the IL. This result may give a reasonable explanation for the origin of the UCST behavior of aqueous [C4mim][BF4] solution.

Label free non-invasive imaging of topically applied actives in reconstructed human epidermis by confocal Raman spectroscopy

29 July 2013, 09:01:11
Publication date: September 2013
Source:Vibrational Spectroscopy, Volume 68
Author(s): Franziska D. Fleischli , Stephanie Mathes , Christian Adlhart
Raman spectroscopy has become a versatile tool for the in vivo characterization of skin. Here we describe use of Raman spectroscopy for high resolution optical cross sectioning to resolve skin constituents and administered drugs at the cellular level. Percutaneous penetration is typically studied using permeation cells with biopsies of animals or human skin. Although this technique provides valuable clinical data, little insight is gained in the microstructure of drug penetration (intercellular or transcellular) or in the mode of action of applied vehicles or penetration enhancers. Therefore, a Raman microspectroscopic method was combined with a confocal scanning setup to image the microstructure of commercially available skin models (SkinEthic®) and the spatial distribution of penetrated actives. The models’ microstructure was scanned without any special treatment or environment such as cutting, staining, freezing, or application of vacuum. The non-invasive Raman images reveal the layered structure of stratum corneum. This in particular for lipids while water tends to be more evenly distributed. When penetration of the hydrophilic active glycerol and the lipophilic octyl methoxycinnamate, OMC, was studied, a strong correlation between the local distribution of skin constituents and the hydrophilic/lipophilic character of the active was observed.

High-pressure Raman scattering of MgMoO4

29 July 2013, 09:01:11
Publication date: September 2013
Source:Vibrational Spectroscopy, Volume 68
Author(s): M.N. Coelho , P.T.C. Freire , M. Maczka , C. Luz-Lima , G.D. Saraiva , W. Paraguassu , A.G. Souza Filho , P.S. Pizani
In this paper, we present results of high-pressure Raman scattering studies in β-MgMoO4 from atmospheric to 8.5GPa. The experiments were carried out using methanol–ethanol as pressure medium. By analyzing the pressure dependence of the Raman data (change in the number of lattice modes, splitting of bands and wavenumber discontinuities) we were able to observe a phase transition undergone by the β-MgMoO4 at 1.4GPa, which is only completed at ∼5GPa. The transition was observed to be irreversible and the modifications in the Raman spectra were attributed to the changes in coordination of Mo ions from tetrahedral to octahedral. The transition possibly changes the original C2/m symmetry to C2/m or to P2/c. Implication on the phase transition for similar molybdate structures, such as α-MnMoO4, is also highlighted.

Effect of thermal annealing on the microstructure of P3HT thin film investigated by RAIR spectroscopy

29 July 2013, 09:01:11
Publication date: September 2013
Source:Vibrational Spectroscopy, Volume 68
Author(s): Linlin An , Yongxin Duan , Yuan Yuan , Lijuan Zhou , Jianming Zhang
The influence of thermal annealing on the structural ordering and orientation rearrangement of as cast P3HT thin film (<100nm) has been studied by reflection absorption infrared spectroscopy (RAIR). In order to erase the effect of temperature on the spectral intensity, two thermal procedures have been used to investigate the annealing-induced structural change of P3HT thin film. One is the continuous heating mode, in which the RIAR spectra were in situ collected during the heating process. The other is the stepwise heating mode, that is the isothermal annealing, and the spectra were ex situ collected at room temperature after the thermal treatment. It is found that thermal annealing can enhance the π–π interaction in P3HT crystal domain, whereas the improvement on the degree of crystallinity is not so obviously. Meanwhile, our results suggest that annealing-induced structural rearrangement on π–π stacking is irreversible, whereas the change on hexyl side chain packing is reversible.

Immobilised gold nanostars in a paper-based test system for surface-enhanced Raman spectroscopy

29 July 2013, 09:01:11
Publication date: September 2013
Source:Vibrational Spectroscopy, Volume 68
Author(s): Dora Mehn , Carlo Morasso , Renzo Vanna , Marzia Bedoni , Davide Prosperi , Furio Gramatica
Paper-based SERS active substrates were prepared adsorbing spherical and star-shaped gold nanoparticles on a standard filter paper support. Besides the deposition conditions, morphological parameters of the particles were found to strongly affect the enhancer properties of the substrates. The developed substrate was tested regarding surface homogeneity as well as in the quantitative analysis of malachite green, – a well documented Raman reporter dye – and proved to be capable also to detect the oxidation products of apomorphine, a well-known drug molecule used in Parkinson's disease. This material is simple to prepare, easy to handle and dispose and as such it could be a perfect target for further development of a new family of mass-produced, cheap solid SERS substrates. 

New Supercritical Fluid Extractor for the Processing of Natural Products

Supercritical Fluid Technologies (SFT) is pleased to introduce a new pilot scale supercritical extractor for the processing of natural products. The SFT-NPX-10 is designed to simplify the extraction of a wide variety of natural products, and to facilitate the transition from laboratory scale equipment to production processing systems.

The SFT-NPX-10 is designed to perform supercritical fluid extractions in either single or dual 10 Liter sample vessels with single or dual separators, resulting in maximum efficiency. A Coriolis mass flow meter guarantees precise mass flow measurement.  A pneumatic CO2 pump with an integral pre-chiller is used to maximize pumping efficiency.  A programmable controller is available as an upgrade for automated regulation of pressure, temperature and process cycles.


Using supercritical CO2 to perform extractions on botanicals, herbs, spices and other natural product materials has significant benefits over the use of traditional liquid solvents. While the supercritical fluid possesses many of the same characteristics of a liquid solvent, it adds the benefits of high diffusivity and pressure tunable solvency power. Additionally, no residual solvents are in either the extract or remaining biomass. There is no need to perform a distillation step since, upon dropping pressure, the CO2 becomes a gas. The extracted material is pure and in its natural state. The CO2 may be safely vented or optionally recycled for even greater efficiency. Since the solvency power of the fluid is pressure dependent, it is possible to “fractionate” to obtain multiple compositions from a single raw material. This makes practical some separations that are difficult or impossible to do with traditional liquid solvent and distillation processing.

Thursday 25 July 2013

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:

Analytical chemistry of the persistent organic pollutants identified in the Stockholm Convention: A review

25 July 2013, 08:50:21
Publication date: 6 August 2013
Source:Analytica Chimica Acta, Volume 790
Author(s): Weiguang Xu , Xian Wang , Zongwei Cai
Persistent organic pollutants (POPs) are major environmental concern due to their persistence, long-range transportability, bio-accumulation and potentially adverse effects on living organisms. Analytical chemistry plays an essential role in the measurement of POPs and provides important information on their distribution and environmental transformations. Much effort has been devoted during the last two decades to the development of faster, safer, more reliable and more sensitive analytical techniques for these pollutants. Since the Stockholm Convention (SC) on POPs was adopted 12 years ago, analytical methods have been extensively developed. This review article introduces recent analytical techniques and applications for the determination of POPs in environmental and biota samples, and summarizes the extraction, separation and instrumental analyses of the halogenated POPs. Also, this review covers important aspects for the analyses of SC POPs (e.g. lipid determination and quality assurance/quality control (QA/QC)), and finally discusses future trends for improving the POPs analyses and for potential new POPs.

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Simultaneous measurement of two enzyme activities using infrared spectroscopy: A comparative evaluation of PARAFAC, TUCKER and N-PLS modeling

25 July 2013, 08:50:21
Publication date: 6 August 2013
Source:Analytica Chimica Acta, Volume 790
Author(s): Andreas Baum , Per Waaben Hansen , Anne S. Meyer , Jørn Dalgaard Mikkelsen
Enzymes are used in many processes to release fermentable sugars for green production of biofuel, or the refinery of biomass for extraction of functional food ingredients such as pectin or prebiotic oligosaccharides. The complex biomasses may, however, require a multitude of specific enzymes which are active on specific substrates generating a multitude of products. In this paper we use the plant polymer, pectin, to present a method to quantify enzyme activity of two pectolytic enzymes by monitoring their superimposed spectral evolutions simultaneously. The data is analyzed by three chemometric multiway methods, namely PARAFAC, TUCKER3 and N-PLS, to establish simultaneous enzyme activity assays for pectin lyase and pectin methyl esterase. Correlation coefficients R pred 2 for prediction test sets are 0.48, 0.96 and 0.96 for pectin lyase and 0.70, 0.89 and 0.89 for pectin methyl esterase, respectively. The retrieved models are compared and prediction test sets show that especially TUCKER3 performs well, even in comparison to the supervised regression method N-PLS.

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Electrochemical immunoassay for thyroxine detection using cascade catalysis as signal amplified enhancer and multi-functionalized magnetic graphene sphere as signal tag

25 July 2013, 08:50:21
Publication date: 6 August 2013
Source:Analytica Chimica Acta, Volume 790
Author(s): Jing Han , Ying Zhuo , Yaqin Chai , Yanqing Yu , Ni Liao , Ruo Yuan
This paper constructed a reusable electrochemical immunosensor for the detection of thyroxine at an ultralow concentration using cascade catalysis of cytochrome c (Cyt c) and glucose oxidase (GOx) as signal amplified enhancer. It is worth pointing out that numerous Cyt c and GOx were firstly carried onto the double-stranded DNA polymers based on hybridization chain reaction (HCR), and then the amplified responses could be achieved by cascade catalysis of Cyt c and GOx recycling with the help of glucose. Moreover, multi-functionalized magnetic graphene sphere was synthesized and used as signal tag, which not only exhibited good mechanical properties, large surface area and an excellent electron transfer rate of graphene, but also possessed excellent redox activity and desirable magnetic property. With a sandwich-type immunoreaction, the proposed cascade catalysis amplification strategy could greatly enhance the sensitivity for the detection of thyroxine. Under the optimal conditions, the immunosensor showed a wide linear ranged from 0.05pgmL−1 to 5ngmL−1 and a low detection limit down to 15fgmL−1. Importantly, the proposed method offers promise for reproducible and cost-effective analysis of biological samples.

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Non-conductive nanomaterial enhanced electrochemical response in stripping voltammetry: The use of nanostructured magnesium silicate hollow spheres for heavy metal ions detection

25 July 2013, 08:50:21
Publication date: 6 August 2013
Source:Analytica Chimica Acta, Volume 790
Author(s): Ren-Xia Xu , Xin-Yao Yu , Chao Gao , Yu-Jing Jiang , Dong-Dong Han , Jin-Huai Liu , Xing-Jiu Huang
Nanostructured magnesium silicate hollow spheres, one kind of non-conductive nanomaterials, were used in heavy metal ions (HMIs) detection with enhanced performance for the first time. The detailed study of the enhancing electrochemical response in stripping voltammetry for simultaneous detection of ultratrace Cd2+, Pb2+, Cu2+ and Hg2+ was described. Electrochemical properties of modified electrodes were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The operational parameters which have influence on the deposition and stripping of metal ions, such as supporting electrolytes, pH value, and deposition time were carefully studied. The anodic stripping voltammetric performance toward HMIs was evaluated using square wave anodic stripping voltammetry (SWASV) analysis. The detection limits achieved (0.186nM, 0.247nM, 0.169nM and 0.375nM for Cd2+, Pb2+, Cu2+ and Hg2+) are much lower than the guideline values in drinking water given by the World Health Organization (WHO). In addition, the interference and stability of the modified electrode were also investigated under the optimized conditions. An interesting phenomenon of mutual interference between different metal ions was observed. Most importantly, the sensitivity of Pb2+ increased in the presence of certain concentrations of other metal ions, such as Cd2+, Cu2+ and Hg2+ both individually and simultaneously. The proposed electrochemical sensing method is thus expected to open new opportunities to broaden the use of SWASV in analysis for detecting HMIs in the environment.

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Determination of hormones in milk by hollow fiber-based stirring extraction bar liquid–liquid microextraction gas chromatography mass spectrometry

25 July 2013, 08:50:21
Publication date: 6 August 2013
Source:Analytica Chimica Acta, Volume 790
Author(s): Xu Xu , Fanghui Liang , Jiayuan Shi , Xin Zhao , Zhuang Liu , Lijie Wu , Ying Song , Hanqi Zhang , Ziming Wang
The hollow fiber-based stirring extraction bar liquid–liquid microextraction was applied to the extraction of hormones, including 17-α-ethinylestradiol, 17-α-estradiol, estriol, 17-β-estradiol, estrone, 17-α-hydroxyprogesterone, medroxyprogesterone, progesterone and norethisterone acetate, in milk. The present method has the advantages of both hollow fiber-liquid phase microextraction and stirring bar sorptive extraction. The stirring extraction bar was used as both the stirring bar of microextraction, and extractor of the analytes, which can make extraction, clean-up and concentration be carried out in one step. When the extraction was completed, the stirring extraction bar was easy isolated from the extraction system with the magnet. Several experimental parameters, including the type of extraction solvent, the number of hollow stirring extraction bar, extraction time, stirring speed, ionic strength, and desorption conditions were investigated and optimized. The analytes in the extract were derived and determined by gas chromatography mass spectrometry. Under optimal experimental conditions, good linearity was observed in the range of 0.20–20.00ngmL−1. The limits of detection and quantification were in the range of 0.02–0.06ngmL−1 and 0.07–0.19ngmL−1, respectively. The present method was applied to the analysis of milk samples, and the recoveries of analytes were in the range of 93.6–104.6% with the relative standard deviations ranging from 1.6% to 6.2% (n =5). The results showed that the present method was a rapid and feasible method for the determination of hormones in milk samples.

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Combination of computational methods, adsorption isotherms and selectivity tests for the conception of a mixed non-covalent–semi-covalent molecularly imprinted polymer of vanillin

25 July 2013, 08:50:21
Publication date: 6 August 2013
Source:Analytica Chimica Acta, Volume 790
Author(s): Kinga Puzio , Raphaël Delépée , Richard Vidal , Luigi A. Agrofoglio
A novel molecularly imprinted polymer (MIP) for vanillin was prepared by photo initiated polymerization in dichloromethane using a mixed semi-covalent and non-covalent imprinting strategy. Taking polymerisable syringaldehyde as “dummy” template, acrylamide was chosen as functional monomer on B3LYP/6-31+G(d,p) density functional theory computational method basis with counterpoise. The binding parameters for the recognition of vanillin on imprinted polymers were studied with three different isotherm models (Langmuir, bi-Langmuir and Langmuir–Freundlich) and compared. The results indicate an heterogeneity of binding sites. It was found and proved by DFT calculations that the specific binding of vanillin in the cavities is due to non-covalent interactions of the template with the hydroxyphenyl- and the amide-moieties. The binding geometry of vanillin in the MIP cavity was also modelled. The obtained MIP is highly specific for vanillin (with an imprinting factor of 7.4) and was successfully applied to the extraction of vanillin from vanilla pods, red wine spike with vanillin, natural and artificial vanilla sugar with a recovery of 80%.

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Use of a mobile phone for potentiostatic control with low cost paper-based microfluidic sensors

25 July 2013, 08:50:21
Publication date: 6 August 2013
Source:Analytica Chimica Acta, Volume 790
Author(s): Jacqui L. Delaney , Egan H. Doeven , Anthony J. Harsant , Conor F. Hogan
By exploiting its ability to play sounds, a mobile phone with suitable software installed can serve the basic functions of a potentiostat in controlling an applied potential to oxidise ECL-active molecules, while the resultant photonic signal is monitored using the camera in video mode. In combination with paper microfluidic sensors this opens significant new possibilities for low-cost, instrument-free sensing.

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A reliable and environmentally-friendly liquid-chromatographic method for multi-class determination of fat-soluble UV filters in cosmetic products

25 July 2013, 08:50:21
Publication date: 6 August 2013
Source:Analytica Chimica Acta, Volume 790
Author(s): Alberto Chisvert , Isuha Tarazona , Amparo Salvador
An environmentally-friendly analytical method for the simultaneous determination of 15 fat-soluble ultraviolet (UV) filters currently authorized by the European Union regulation on cosmetic products has been developed. The determination was performed by liquid chromatography with UV spectrophotometric detection. Different parameters, such as type of column, oven temperature, mobile phase composition and flow rate were studied. The best chromatographic separation was obtained under the following conditions: C18 column set at 60°C and gradient ethanol:water (containing 1% formic acid and 20mM of 2-hydroxypropyl-β-cyclodextrin) as mobile phase pumped at 1mLmin−1. 2-Hydroxypropyl-β-cyclodextrin was added as mobile phase modifier to achieve the complete resolution of some of the chromatographic peaks. The 15 target compounds were separated in less than 30min. The method was satisfactorily validated by analyzing three laboratory-made cosmetic samples besides of eleven commercially available cosmetic products containing different combination of the target UV filters. Good accordance of the found levels compared with those of the laboratory-made samples and those of the commercial samples (when available) was achieved. Moreover, excellent recoveries (97–104%) and good intra-day and inter-day precision values at different concentration levels, besides limits of detection values below the μgmL−1 level, were obtained. These good analytical features, as well as their environmentally-friendly characteristics, make the presented method suitable not only for routine analysis in cosmetics industries, but also as candidate reference method for sunscreen analysis.

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