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:

http://rss.sciencedirect.com/publication/science/5787

Selected papers from the latest issue:

Common methods for the chiral determination of amphetamine and related compounds II. Capillary electrophoresis and nuclear magnetic resonance

22 October 2011, 22:12:50

Publication year: 2011
Source: TrAC Trends in Analytical Chemistry, Available online 21 October 2011
Justyna Małgorzata Płotka, Calum Morrison, Marek Biziuk
Amphetamine (AM) group and related ring-substituted substances are generally synthetic compounds, belonging to one of the most heavily abused drug groups in recent years. Some compounds in this class also originate from plants. Analysis of the enantiomers of AM-type compounds and metabolites is extremely important for a number of scientific disciplines. From studies of biological activity or mechanisms through determination of precursor molecules in a criminal investigation all use analytical procedures.This article reviews capillary electrophoresis and nuclear magnetic resonance as among the most common, useful methods for the chiral determination of AMs and AM-derived designer drugs in different matrices, including blood, hair, urine, and medicaments. We took into consideration articles published in the past 15 years. We describe commonly used types of chiral derivatization reagent and chiral stationary phase. Tables summarize basic information about conditions and reference data of each procedure. Other methods (e.g., gas chromatography, liquid chromatography and high-performance liquid chromatography, and thin-layer chromatography were described in Part I [Trends Anal. Chem. 30 (2011) 1139].

Highlights

► CE and NMR are useful techniques for the chiral determination of AM type compounds. ► Indirect or direct methods are used for the successful separation of enantiomers. ► CE enantioseparation offers many advantages even over the chromatographic techniques. ► Enantioseparation using microchip-CE with respect to drug analysis is possible. ► NMR techniques usually are complementary to chromatographic approaches.

Removal of sulfur from a solvent extract

22 October 2011, 22:12:50

Publication year: 2011
Source: TrAC Trends in Analytical Chemistry, Available online 21 October 2011
Agata Mechlińska, Lidia Wolska, Jacek Namieśnik
The presence of sulfur in a solvent extract that is to be analyzed chromatographically impairs and sometimes precludes proper interpretation of the chromatogram, as the sulfur peak masks the peaks of other compounds present in the sample, and sulfur also disrupts the operation of the mass detector. This means that discrepancies in the results can lead to erroneous interpretations and false assessments of environmental risk. For this reason, sulfur should be removed from an extract prior to chromatographic analysis and determined in a separate analytical run using an appropriate procedure.This article presents a critical analysis of known methods for removing elemental sulfur from solvent extracts prior to the final determination step of chemicals in the group comprising polychlorinated biphenyls, polyaromatic hydrocarbons and polybrominated diphenyl ethers.

Highlights

► Critical analysis of known methods of removing elemental sulfur from solvent extracts. ► Elemental sulfur is a serious interferent. ► Sulfur must be removed prior to chromatographic analysis & determined in a separate analytical run. ► Sulfur in extract preludes proper interpretation of the chromatogram & disrupts the operation of a mass detector.

Analytical methods for the quantification of volatile aromatic compounds

20 October 2011, 22:17:31

Publication year: 2011
Source: TrAC Trends in Analytical Chemistry, Available online 19 October 2011
Małgorzata Biniecka, Sergio Caroli
The investigation of odorants is not an easy task, which needs to be undertaken in the context of fit-for-purpose quality systems. To date, great attention has been paid to determination of the volatile fractions of odorants, since they are responsible for the attributes of global flavor [i.e. a combination of olfactory (aroma) and gustatory (taste) sensations produced by chemicals]. This kind of determination can be carried out by analytical techniques [e.g., gas chromatography (GC) combined with mass spectrometry and/or olfactometric GC]. Methods complementary to GC analysis are available, allowing assessment of the olfactory impact by an electronic nose (e-nose) or a panel of selected individuals. Also, we consider some innovative analytical techniques to study the effects of odorants in food during consumption.

Highlights

► Identification and quantification of volatile fractions of odorants. ► Global flavour as a combination of olfactory (aroma) and gustatory (taste) sensations. ► Gas-chromatography - mass spectroscopy analysis of odorants. ► Gas-chromatography – Olfactometry analysis of odorants. ► Electronic nose.

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:

http://rss.sciencedirect.com/publication/science/5293

Selected papers from the latest issue:

Theoretical study on resonance Raman scattering for C60molecules in benzene solutions

23 October 2011, 03:05:06

Publication year: 2011
Source: Vibrational Spectroscopy, Available online 21 October 2011
Ren-hui Zheng, Wen-mei Wei, Yuan-yuan Sun, Qiang Shi
Resonance Raman spectra for C60molecules in vacuum and benzene solutions have been studied based on density functional theory calculations underIhsymmetry. The displacement parameters of the potential energy minimum along normal coordinates between the ground and excited states for totally symmetric modes are determined, which are small. The solvent effect is found to have a slight influence on Raman intensities. Also, resonance Raman excitation profiles have been investigated.

Spectral inter-conversion analysis of thermally induced structural changes in polyethylene crystals

23 October 2011, 03:05:06

Publication year: 2011
Source: Vibrational Spectroscopy, Available online 21 October 2011
Liping Zhang, Shin Watanabe, Isao Noda, Yuqing Wu
Temperature dependence of conformational disordering in crystals of polyethylene was investigated by the inter-conversion analysis based on the combination of NIR and MIR spectra by means of the partial least-squares regression (PLS2). Two regression models were built based on the spectral range of 1500 - 1250 cmand 4400 - 4200 cmto make the prediction in a wider spectral range. The other models were explored in the relatively narrow two MIR range of 1365 - 1355 and 1471 - 1461 cm(due to the hexagonal phase); and three NIR range of 4354 - 4344 (corresponding to the hexagonal phase), 4327 - 4317 (relating to the orthorhombic phase) and 4261 - 4251 cm(previously unconfirmed conformation). Total of twelve PLS2 models were built based on these infrared spectral ranges and used to carry out the spectral inter-conversion analysis. By spectral inter-conversion, the conformational disordering induced by thermal stimulus was clearly differentiated, and the assignment of a band at 4256 cmin the NIR spectral range was confirmed. The qualitative analysis indicates that the temperature dependency of the band at 4256 cmin the NIR range is very similar to that of the bands at 1360 and 4349 cm(which corresponded to the hexagonal phase) indicating they have the common spectral origin. The quantitative comparison of the prediction deviation values between different multivariate spectral models firmly validate the assignment of the band at 4256 cmto the hexagonal sequence formed in the thermally induced conformational disordering.

Mechanisms of energy dissipation and ultrafast primary events in photostable systems: H-bond, excess electron, biological photoreceptors

23 October 2011, 03:05:06

Publication year: 2011
Source: Vibrational Spectroscopy, Available online 21 October 2011
Halina Abramczyk
The fundamental property of biological systems is photostability. Without photostability no life would be possible. Molecular structures responsible for harvesting of the solar energy must be photostable and resistant to photo-induced chemical changes or must find a way for a recovery. To answer the questions about the photostability we have to understand mechanisms of relaxation and energy dissipation upon an optical excitation. There is a common agreement that such channels are provided by some special features of the potential energy surfaces including the conical intersections. The mechanism that leads to decrease in the energy gap between the excited-state potential and the ground state energy surfaces is related to the coupling between the excited state (electronic or vibrational) and the intramolecular and intermolecular vibrational modes. When the potential energy surfaces approach each other nonadiabatic transitions are facilitated by their close proximity and the rate of radiationless transitions increases. The mechanism seems to be universal both for simple species such as H-bond systems, solvated electrons, and biologically important photoreceptor proteins such as bacteriorhodopsin. In order to study energy dissipation and dynamical alterations in the structure, a system is triggered with laser and monitored with excellent time-resolution. Ultrafast spectroscopies have played an important role in the study of a number of biological processes and have provided unique information about primary events and the mechanism of energy relaxation. Biological activity of molecules is frequently initiated by elementary chemical reactions such as energy and electron transfer, cis-trans isomerizations, or proton transfer. Many of these reactions are usually very fast and efficient and occur on picosecond and femtosecond timescales. This paper reviews recent progress of understanding light-energy collection and dissipation, with a special emphasis on the role of the vibronic coupling in H-bonded systems, solvated electrons and light-initiated biological photoreceptors. We will concentrate on the spectroscopic methods based on the linear and nonlinear responses such as the time resolved coherent anti-Stokes Raman spectroscopy (CARS) and the pump-probe transient femtosecond absorption spectroscopy. Detailed understanding the paths of energy dissipation will reveal mechanisms that mediate light-induced signal transduction as well as the role of photoreceptors in photostability protection and reparation mechanisms in living cells.

AMI ANNOUNCES 15th ANNUAL THERMOPLASTIC CONCENTRATES CONFERENCE

Applied Market Information LLC (AMI) will be hosting Thermoplastic Concentrates 2012 in Coral Springs, FL at the Ft. Lauderdale Marriot Coral Springs Golf Resort on January 31 – February 2, 2012. This will be the fifteenth annual edition of this conference focusing on the color concentrate industry. The entire conference will be launched with the annual golf tournament, sponsored by Cristal Global. All conference attendees are invited to attend the golf tournament for an additional registration fee.

The agenda for Thermoplastic Concentrates 2012 is divided into three sessions. Day one will begin with a Market Overview with reports on the current state of the industry given by AMI’s Research Director, Andrew Reynolds. Americhem will follow up with a forecast on color trends expected for 2012- 2013.

“Session 1- Pigment/Additives” will begin on day 1 with BASF presenting on coloration for sensitive applications followed by Columbian Chemicals Company providing insight on how to get the best from your carbon black.  This session will carry into the second day beginning with EMD Chemicals describing the influences of social trends and color. Selection of TiO2 in plastics will be discussed by Huntsman Pigments and Nubiola will speak on iron oxides and zinc ferrites innovating color solutions. FP-Pigments will then present on TiO2 replacement providing masterbatch optimization. The Shepherd Color Company will discuss inorganic pigments meeting regulatory and performance requirements. The Pigments/Additives session will conclude with an additive paper from R.T. Vanderbilt explaining hindered amine light stabilizers and sulfur.

“Session 2- Equipment/Technology” will include presentations from machinery manufacturers sharing the latest updates on improving performance.  Featured presentations will be given from Leistritz, Buss Inc., Coperion, K-Tron, as well as Maag-Automatik.

“Session 3- Business Forum” will be held on day 3 and will include presentations on a wide variety of topics including social media tips and organizational development. Attendees will hear from forward-thinking key players from AFI Global, Techmer PM, and O’Neil Color. The conference will conclude with a presentation by Andrew Reynolds comparing the current status and outlook for the thermoplastic concentrate market in North America.

There will be an exhibition running alongside the conference. The table tops will allow companies to display their services and products to a highly targeted audience. Also, all social gatherings and the cocktail reception will be hosted in the Exhibition Room.

The full conference brochure can be found at http://www.amiplastics-na.com/Events/Event.aspx?code=C450&sec=2213



Just Published: Journal of Chromatography A

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:

http://rss.sciencedirect.com/publication/science/5248

Selected papers from the latest issue:

Invited Review, submitted for consideration to The Journal of Chromatography A Technology Trends in Antibody Purification

21 October 2011, 03:11:25

Publication year: 2011
Source: Journal of Chromatography A, Available online 20 October 2011
Pete Gagnon
This article reviews technology trends in antibody purification. The first section discusses non-chromatography methods, including precipitation, liquid-liquid extraction, and high performance tangential flow filtration. The second addresses chromatography methods. It begins with discussion of fluidized and fixed bed formats. It continues with stationary phase architecture: diffusive particles, perfusive particles, membranes and monoliths. The remainder of the section reviews recent innovations in size exclusion, anion exchange, cation exchange, hydrophobic interaction, immobilized metal affinity, mixed-mode, and bioaffinity chromatography. The third section addresses an emerging trend of formulating process buffers to prevent or correct anomalies in the antibodies being purified. Methods are discussed for preventing aggregate formation, dissociating antibody-contaminant complexes, restoring native antibody from aggregates, and conserving or restoring native disulfide pairing.

Multidimensional Enantio Gas Chromtography/Mass Spectrometry and Gas Chromatography-Combustion-Isotopic Ratio Mass Spectrometry for the Authenticity Assessment of Lime Essential Oils (C. aurantifoliaSwingle andC. latifoliaTanaka)

21 October 2011, 03:11:25

Publication year: 2011
Source: Journal of Chromatography A, Available online 20 October 2011
Ivana Bonaccorsi, Danilo Sciarrone, Luisa Schipilliti, Paola Dugo, Luigi Mondello, ...
This article focuses on the genuineness assessment of Lime oils (C. aurantifoliaSwingle andC. latifoliaTanaka), by Multi Dimensional Gas Chromatography (MDGC) to determine the enantiomeric distribution of α-thujene, camphene, β-pinene, sabinene, α-phellandrene, β-phellandrene, limonene, linalool, terpinen-4-ol, α-terpineol and by Gas Chromatography Combustion Isotope Ratio Mass Spectrometry (GC-C-IRMS) to determine the isotopic ratios of α-pinene, β-pinene, limonene, α-terpineol, neral, geranial,β-caryophyllene, trans-α-bergamotene, germacrene B. To the author's knowledge this is the first attempt to assess the authenticity and differentiate Persian Lime from Key lime oils by GC-C-IRMS. The results of the two analytical approaches were compared. The simultaneous use of the two techniques provides more reliable capability to detect adulteration inCitrusessential oils. In fact, in some circumstance only one of the two techniques allows to discriminate adulterated or contaminated oils. In cases where only small anomalies are detected by the two techniques due to subtle adulterations, their synergic use allows to express judgments. The advantage of both techniques is the low number of components the analyst must evaluate, reducing the complexity of the data necessary to deal with. Moreover, the conventional analytical approach based on the evaluation of the whole volatile fraction can fail to reveal the quality of the oils, if the adulteration is extremely subtle.

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:

http://rss.sciencedirect.com/publication/science/5216

Selected papers just published:

DEVELOPMENT OF GC-MS/MS METHOD WITH PROGRAMMABLE TEMPERATURE VAPORIZATION LARGE VOLUME INJECTION FOR MONITORING OF 17β-ESTRADIOL AND 2-METHOXYESTRADIOL IN PLASMA

20 October 2011, 21:58:47

Publication year: 2011
Source: Analytica Chimica Acta, Available online 20 October 2011
A.K. Tsakalof, D.C. Gkagtzis, G.N. Koukoulis, C.S. Hadjichristodoulou
Monitoring of estradiol and its metabolites in biological samples is essential for the accurate diagnosis of a number of endocrine diseases. In this study, a sensitive, precise and specific GC-MS/MS method for the quantification of 17β-estradiol (17-BE) and its main metabolite, 2-methoxyestradiol (2MEOE), in plasma was developed and validated. Plasma concentrations of these steroids are currently investigated as diagnostic markers for pre-eclampsia, a systematic disorder of pregnancy and a leading cause of maternal and fetal morbidity and mortality worldwide.The method comprised treatment of the plasma sample by protein precipitation and subsequent isolation of steroids by solid phase extraction, derivatization of steroids by trifluoroacetic anhydride and GC-MS/MS analysis of the derivatized steroids. The large volume (10 μL) injection with the assistance of a Programmed Temperature Vaporization (PTV) injector in solvent split mode allowed a substantial increase in the sensitivity of the method.The ion trap MS was operated in optimized Product Ion Scan. By increasing the damping gas flow in the ion trap from the conventional 0.3 mL/min to 2 mL/min, ion fragmentation was reduced and the instrument response was enhanced substantially. As a result, mass spectra with predominant molecular ions were acquired and molecular ions of the steroids of interest were used as precursor ions thus increasing specificity of the method.Under optimized GC-MS/MS conditions in product ion mode, the Limit of Detection (LOD) of the analyzed steroids ranged from 18.4 pg*mLfor 17BE to 5.5 pg*mLfor 2MEOE (S/N = 3). The instrument response was linear in the investigated concentration range from 0.1 to 10 ng*mL-1 with R > 0.99 for 17BE and 2MEOE. The intra-batch accuracy obtained for quality control samples at the concentration levels of 0.1, 1, 3, 7 ng*mL-1 ranged from 94.9 to 109.9% for 17BE and from 99.9 to 104.5% for 2MEOE.

Highlights

► GC-MS/MS method for the quantification of 17β-estradiol and 2-methoxyestradiol in plasma. ► Increased sensitivity with Ion Trap operated under increased damping gas flow. ► Straightforward and efficient method for steroids’ isolation from plasma is described. ► LOD 5.5 and 18.4 pg*mL-1 for 2-methoxyestradiol and 17β-estradiol respectively.

Molecular criteria for discriminating museum Asian lacquerware from different vegetal origins by pyrolysis gas chromatography/mass spectrometry

20 October 2011, 21:58:47

Publication year: 2011
Source: Analytica Chimica Acta, Available online 19 October 2011
Anne-Solenn Le Hô, Martine Regert, Olivier Marescot, Chloé Duhamel, Juliette Langlois, ...
This paper focuses on the identification of several chemical markers of vegetal species of Oriental lacquers with the aim at providing a methodology consistent with sampling restrictions necessarily applied in the field of cultural heritage. The method proposed is based on rapid and easy single step thermally assisted hydrolysis–methylation (THM) pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) analysis that can be carried out with a minimum amount of matter (typically 10 μg for a sample collected on a museum or an archaeological object).The main contribution of this study is to provide multiple molecular criteria for discriminating the three Asian species used for making lacquers, namelyRhus vernicifluaStokes,Rhus succedaneaandMelanorrhoea usitata. Because these trees grow in specific areas, identifying the species involved in ancient lacquer coatings also provides geobotanical data and fruitful information on the exchange networks and trading routes developed by ancient societies.With this purpose, a systematic study of all pyrolysis products of lacquer coatings was carried out on modern dried lacquer films from authentified provenance. It was demonstrated that the whole pyrolysis products play a significant role in identifying the vegetal species. The chemotaxonomic value of homologous series of alkanes, alkenes and benzene derivatives, rarely explored until now, was assessed. It was shown that the combination of data related to five distinct groups of pyrolytic markers (composition and/or distribution of alkanes, alkenes and benzene, alkenyl-, alkylcatechol and phenol derivatives) provided new strong criteria to establish vegetal origin and provenance of Asian artworks, eventhough they have been largely altered over time.Case studies of archaeological Chinese lacquered artefacts and Japanese Buddhistic altar were thereafter successfully investigated to address informative potential and efficiency of these criteria on ancient and degraded lacquer coatings.

Highlights

► chemical geobotanical markers of Asian lacquers to discriminate vegetal species ► conservation of ancient lacquerware relies to a knowledge on their materials ► small specimens have to be extracted from the art works to preserve them

Capillary Electrophoretic Studies on Displacement and Proteolytic Cleavage of Surface Bound Oligohistidine Peptide on Quantum Dots

20 October 2011, 21:58:47

Publication year: 2011
Source: Analytica Chimica Acta, Available online 19 October 2011
Jianhao Wang, Jiang Xia
Subtle changes in the chemical structure or the composition of surface bound ligands on quantum dots (QDs) remain difficult to detect. Here we describe a facile setup for fluorescence detection coupled capillary electrophoresis (CE-FL) and its application in monitoring ligand displacement on QDs through metal-affinity driven assembly. We also describe the use of CE-FL to monitor amide bond cleavage by a specific protease, based on Förster resonance energy transfer (FRET) between Cy5 and QDs spaced by a hexahistidine peptide (H6-Cy5). CE-FL allowed separation of unbound QDs and ligand bound QDs and also revealed an ordered assembly of H6-Cy5 on QDs. In a ligand displacement experiment, unlabeled hexahistidine peptide gradually displaced surface bound H6-Cy5 until finally reaching equilibrium. The displacement intermediates were clearly separated on CE-FL. Proteolytic cleavage of surface bound H6-Cy5 by thrombin was monitored by CE-FL through mobility shift, peak broadening, and FRET changes. Enzymatic parameters thus obtained were comparable with those measured by fluorescence spectroscopy.

Highlights

► Capillary electrophoresis reveals details in QD-oligohistidine peptide binding; ► An ordered assembly of peptides on QDs was revealed; ► Intermediates of QD-peptide binding were found; ► Detailed displacement kinetics was revealed; ► Proteolysis of surface ligands causes mobility shift and peak broadening in CE

Protein Separation by Capillary Gel Electrophoresis: A Review

20 October 2011, 21:58:47

Publication year: 2011
Source: Analytica Chimica Acta, Available online 19 October 2011
Zaifang Zhu, Joann J. Lu, Shaorong Liu
Capillary gel electrophoresis (CGE) has been used for protein separation for more than two decades. Due to the technology advancement, current CGE methods are becoming more and more robust and reliable for protein analysis, and some of the methods have been routinely used for the analysis of protein-based pharmaceuticals and quality controls. In light of this progress, we survey 147 papers related to CGE separations of proteins and present an overview of this technology. We first introduce briefly the early development of CGE. We then review the methodology, in which we specifically describe the matrices, coatings, and detection strategies used in CGE. CGE using microfabricated channels and incorporation of CGE with two-dimensional protein separations are also discussed in this section. We finally present a few representative applications of CGE for separating proteins in real-world samples.

JEOL USA Partners with Chilean Agent Arquimed

JEOL USA, a leading supplier of scientific and industrial instrumentation including electron microscopes, mass spectrometers and nuclear magnetic resonance spectrometers, and headquartered in Peabody, Massachusetts, has entered an agreement with Arquimed, Ltda. making Arquimed JEOL’s exclusive agent in Chile. Arquimed, located in Santiago, has a 75-year history as one of Chile’s largest and most respected distributors of scientific, medical, educational, and industrial tools and equipment.

While JEOL USA has long had a presence in Chile and throughout Central and South America, this new partnership signifies increased local support in this active mining, manufacturing and research area.

“We are very impressed by Arquimed’s long history of representing excellent products through outstanding customer service, which is very similar to our own here at JEOL USA,” said Peter Genovese, President. “We look forward to building close and long relationships with our customers and the scientific community in Chile. Our partnership with Arquimed will be a key factor in fulfilling that objective.”

For more information about JEOL USA, Inc. or any JEOL products, visit www.jeolusa.com, or call 978-535-5900.

Humour with impact

Thought you might like this if you haven't seen it already ...

I'm afraid I can't cite the source as it was spotted on Facebook with no reference!