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Current Analytical Chemistry
ISSN: 1573-4110
Current Analytical Chemistry
Volume 1, Number 3, November 2005
Contents
Mass Spectrometry for the Analysis of Highly Charged Sulfated
Carbohydrates Pp.223
Lianli Chi, Jonathan Amster and Robert J. Linhardt
[Abstract]
Liquid Chromatography-Ion Trap-Mass Spectrometry and its Application
to Determine Organic Contaminants in the Environment and Food
Pp.241
Vicente Andreu and Yolanda Picó
[Abstract]
Identification of Degradation Products by Adopting GC or HPLC/MS
Techniques Pp.267
Paola Calza, Claudio Medana, Claudio Baiocchi and
Ezio Pelizzetti
[Abstract]
New Applications, Processing Methods and Pulse
Sequences Using Diffusion NMR Pp.289
J.C. Cobas, P. Groves, M. Martín-Pastor and A.
De Capua
[Abstract]
Ligand Screening by Saturation-Transfer Difference
(STD) NMR Spectroscopy Pp.307
V.V. Krishnan
[Abstract]
Flow Injection-Capillary Electrophoresis (FI-CE):
Recent Advances and Applications Pp.321
Grady Hanrahan, Froseen Dahdouh, Keith Clarke and Frank
A. Gomez
[Abstract]
Recent Advances in On-line Solvent Extraction Exploiting
Flow Injection/Sequential Injection Analysis Pp.329
Manuel Miró, José Manuel Estela and Víctor
Cerdà
[Abstract]
Particle Separation in Microfluidic Devices —
SPLITT Fractionation and Microfluidics Pp.345
Yonghao Zhang, Robert W. Barber and David R. Emerson
[Abstract]
Protein Sequence and Structure Databases: A Review
Pp.355
Marcos J. Araúzo-Bravo and Shandar Ahmad
[Abstract]
The Role of Atomic Spectrometric Techniques in the
Determination of Chemical Elements in Atmospheric Aerosols
Pp.373
Patricia Smichowski, Darío Gómez and Griselda
Polla
[Abstract]
Abstracts
[Back to top]
Mass Spectrometry for the Analysis of Highly Charged
Sulfated Carbohydrates
Lianli Chi, Jonathan Amster and Robert J. Linhardt
Sulfated polysaccharides and their oligosaccharide components
play an important biological role in physiological and pathophysiological
processes. Glycosaminoglycans, such as heparin, are currently
used as pharmaceutical agents to control coagulation. Moreover,
there are intensive efforts in developing rapid approaches
for the analysis of such bioactive carbohydrates to assess
their pharmacological activity and in glycomic applications.
Soft ionization methods of mass spectrometry have been applied
with recent success in the analysis of sulfated carbohydrates.
This review will examine the application of mass spectrometry
in the compositional analysis and structural characterization
of these important highly charged molecules.
[Back to top]
Liquid Chromatography-Ion Trap-Mass Spectrometry and
its Application to Determine Organic Contaminants in the Environment
and Food
Vicente Andreu and Yolanda Picó
Recent experiences with liquid chromatography-quadrupole
ion trap-mass spectrometry (LC-QITMS), as an analytical tool
for determining trace amounts of organic contaminants in food
and environmental samples, are addressed in this review. A
brief introduction to the fundamental theory for quadrupole
ion trap devices illustrates possibilities and limitations
of this technique. Special attention is paid to the impact
of sample preparation and chromatography on the ionization
efficiency of analytes isolated from complex food and environmental
matrices. The capacity to provide useful data for quantifying
organic contaminants, and the possibility of obtaining structural
information for identifying target and non-target compounds,
are discussed. The flexibility, high sensitivity and multi-stage
tandem mass spectrometric capability of the QIT are all illustrated.
Contemporary applications of this technique to study organic
contaminants in food and environment are presented.
[Back to top]
Identification of Degradation Products by Adopting
GC or HPLC/MS Techniques
Paola Calza, Claudio Medana, Claudio Baiocchi and Ezio
Pelizzetti
The persistence of pesticides and drugs in products destined
for human consumption is of great concern, in particular because
of their potential carcinogenic character. However, often
the transformation products formed through degradation processes
possess higher toxicity than the parent compounds. It is then
of primary importance not only to achieve their abatement
(through purification procedures), but also to detect and
identify the formed by-products, in order to evaluate their
formation kinetics, stability and toxicity.
For this purpose, in the present review we will study in depth,
the transformation pathways followed by molecules belonging
to different classes of compounds, i.e pesticides, drugs and
dyes and their derivatives in photo-assisted, environmental
and biological studies, where they have been identified and
characterized by means of hyphenated techniques. Particular
attention will be paid to degradation simulating models, such
as the photocatalytic process on titanium dioxide.
[Back to top]
New Applications, Processing Methods and Pulse Sequences
Using Diffusion NMR
J.C. Cobas, P. Groves, M. Martín-Pastor
and A. De Capua
Diffusion NMR, and in particular the DOSY processing method
(Diffusion Ordered SpectroscopY), is an attractive technique
to characterize mixtures without first having to separate
the components. As a result, DOSY can yield a vast amount
of analytical information. General applications of DOSY are
reviewed here although we emphasize specialist applications
that provide unique data. Such applications include the analysis
of kinetic products, the detection of impurities in complex
mixtures and the analysis of foodstuffs.
We also focus on recent applications, such as the incorporation
of DOSY into drug discovery protocols and as a filter in the
analysis of natural product extracts or compound libraries.
Depending on the characteristics of the sample under study,
a careful choice of DOSY NMR experiment and its processing
strategy is required to obtain optimum results. Moreover,
this review describes the strengths and weakness of the different
DOSY experimental and processing methods from the perspective
of its application by the analytical chemist to a larger variety
of sample types.
[Back to top]
Ligand Screening by Saturation-Transfer Difference
(STD) NMR Spectroscopy
V.V. Krishnan
NMR based methods to screen for high-affinity ligands have
become an indispensable tool for designing rationalized drugs,
as these offer a combination of good experimental design of
the screening process and data interpretation methods, which
together provide unprecedented information on the complex
nature of protein-ligand interactions. These methods rely
on measuring direct changes in the spectral parameters, that
are often simpler than the complex experimental procedures
used to study structure and dynamics of proteins. The goal
of this review article is to provide the basic details of
NMR based ligand-screening methods, with particular focus
on the saturation transfer difference (STD) experiment. In
addition, we provide an overview of other NMR experimental
methods and a practical guide on how to go about designing
and implementing them.
[Back to top]
Flow Injection-Capillary Electrophoresis (FI-CE):
Recent Advances and Applications
Grady Hanrahan, Froseen Dahdouh, Keith Clarke and Frank
A. Gomez
This paper presents a comprehensive review of how recent
advances in flow injection-capillary electrophoresis (FI-CE)
technology have led to enhanced separation capabilities of
a wide range of analytes in such areas as biological, environmental,
food, medical and pharmaceutical analysis. Significant developments
in design, detection methodology and applications made in
the last five years are reported. In addition, future perspectives
in FI-CE are considered.
[Back to top]
Recent Advances in On-line Solvent Extraction Exploiting
Flow Injection/Sequential Injection Analysis
Manuel Miró, José Manuel Estela and Víctor
Cerdà
In this paper, the state-of-the-art of automated solvent
extraction procedures exploiting flowing stream techniques
is thoroughly presented and discussed. While flow-injection
liquid-liquid extraction (FI-LLE) was originally associated
with the use of a solvent extractor involving a segmentor
and a phase separator, current analytical trends are focused
on the design and characterisation of novel strategies for
the removal of the classical instrumentation aimed at improving
the efficiency of phase separation as well as the repeatability,
sensitivity and accuracy of the analytical chemical assays.
Salient alternatives implemented in flow systems for on-line
sample processing and detection of the analytes in the phase
of interest, based on the principles of on-tube detection,
membrane-assisted LLE, iterative forward-backward flow, cloud-point
extraction, static-phase separation, single-drop solvent extraction,
and chromatomembrane separations, amongst others, are critically
compared in terms of analytical performance, instrumental
set-up and potential applications. Special emphasis is given
in the bulk of the text to the inherent capability of sequential
injection (SI) analysis to accommodate the new concept of
renewable phase extraction in open tubular reactors, so-called
wetting-film extraction (WFE), which is performed in the conduits
of the SI assembly without the need for any ancillary hardware,
thereby minimizing the risks of sample carryover. Its fundamental
background, critical experimental variables, hyphenation with
flow-through detectors, and analytical figures of merit are
thoroughly discussed and exemplified with selected applications
in the environmental and clinical field.
[Back to top]
Particle Separation in Microfluidic Devices —
SPLITT Fractionation and Microfluidics
Yonghao Zhang, Robert W. Barber and David R. Emerson
In recent years, microfluidic devices have been increasingly
used to separate particles such as colloids, macromolecules,
cells, beads and droplets. Miniaturisation often introduces
new functionalities and paradigms that are not possible at
conventional macroscopic scales. In this paper, split-flow-thin
fractionation techniques for particle separation are reviewed
and the underlying physics of particle migration is discussed.
The potential of these particle separation techniques in the
design of integrated microfluidic systems is described. We
then illustrate how numerical simulation can provide an increased
understanding of the fluid-particle motion. The advantages
of numerical simulation for rational design and operation
of microfluidic devices are highlighted through two practical
examples involving an ultrasonic cell washing system and a
quadrupole magnetic flow sorter.
[Back to top]
Protein Sequence and Structure Databases: A Review
Marcos J. Araúzo-Bravo and Shandar Ahmad
Several protein sequence and structure databases have emerged
from a worldwide effort to curate the information on protein
sequences and their structures. Sequences are written in different
formats and certain standards have evolved. On the other hand,
Protein Data Bank is the largest source of information on
protein structures, and sets standards on the way structural
information should be written. For handling large number of
protein structures and sequences in bioinformatics, a thorough
understanding of the formats and contents of these databases
is required. In this review, we deal with some of the most
common sequence and structure databases. Several protein structure
databases have emerged, dealing with special issues and varieties
of protein structures. We survey the contents and availability
of different databases and review their classification and
mutual linking. Certain quality and financial issues on these
databases are also touched upon.
[Back to top]
The Role of Atomic Spectrometric Techniques in the
Determination of Chemical Elements in Atmospheric Aerosols
Patricia Smichowski, Darío Gómez and Griselda
Polla
This review covers the application of atomic and mass spectrometric
techniques for the determination of metals and metalloids
in atmospheric aerosols. Atomic spectrometric methods based
on flame atomic absorption spectrometry (FAAS), electrothermal
atomic absorption spectrometry (ETAAS), atomic fluorescence
spectrometry (AFS), total reflection X-ray fluorescence (TXRF)
spectrometry and plasma based techniques such as inductively
coupled plasma optical emission spectrometry (ICP-OES) and
inductively coupled plasma-mass spectrometry (ICP-MS) are
reviewed, because a considerable amount of research is presently
performed in this field. The application of atomic and mass
spectrometric techniques for fractionation studies based on
the use of chemical sequential extractions for metal partitioning
in airborne particulate matter and fly ashes are also discussed.
This survey contains; 156 references and covers mainly the
literature published over the last decade.
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