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Current Analytical Chemistry
ISSN: 1573-4110
Current Analytical Chemistry
Volume 3, Number 3, July 2007
Contents
Cyclodextrins Host- Guest Chemistry in Analytical
and Environmental Chemistry Pp. 171-181
Sayo O. Fakayode, Mark Lowry, Kristin A. Fletcher, Xiaodong
Huang, Aleeta M. Powe and Isiah M. Warner
[Abstract]
Recent Applications of Host-Guest Inclusion in Fluorescence-Based
Trace Analysis Pp. 183-195
Brian D. Wagner
[Abstract]
Application of Capillary Electrophoresis in Drug Metabolism
Studies Pp. 197-217
Jie Zhang, Jirí Konecný, Zdenek Glatz, Jos
Hoogmartens and Ann Van Schepdael
[Abstract]
The Expanding Role of Mass Spectrometry in Folate
Research Pp. 219-231
Bryant C. Nelson
[Abstract]
Gene Expression (Microarray) Data Analysis by Chemometric
Methods Pp. 233-237
David X. Zhu, Richard J. Goeke, David L. Baker, James
H. Hamburg, David E. Booth and Stephane E. Booth
[Abstract]
Relaxation During Adiabatic Radiofrequency Pulses
Pp. 239-251
Dennis J. Sorce, Shalom Michaeli and Michael Garwood
[Abstract]
Abstracts
[Back to top]
Cyclodextrins Host- Guest Chemistry in Analytical
and Environmental Chemistry
Sayo O. Fakayode, Mark Lowry, Kristin A. Fletcher, Xiaodong
Huang, Aleeta M. Powe and Isiah M. Warner
Native and modified cyclodextrins (CDs) have been shown to
dramatically affect the properties of guest molecules solubilized
within the relatively hydrophobic interior. By monitoring
changes in photophysical processes, researchers have been
able to determine the stoichiometry and association constants
of the resulting complexes. In addition, chemical modification
of the CD structure as well as the selective binding of analytes
within the CD cavity has lead to remarkable advances in analytical
and environmental applications of CDs. In this review, we
discuss a selection of fundamental studies performed in our
laboratory, primarily using fluorescence spectroscopy as a
tool to study the properties of CD host-guest complexes. In
addition, this review includes recent studies conducted in
other laboratories which are concerned with exploiting the
unique properties of CDs and their inclusion complexes in
order to study energy transfer through the use of photochemical
antennas as well as the development of chemical and environmental
sensors.
[Back to top]
Recent Applications of Host-Guest Inclusion in Fluorescence-Based
Trace Analysis
Brian D. Wagner
Host-guest inclusion complexes represent the simplest
example of a supramolecular system, in which a small “guest”
molecule becomes included within the interior cavity of a
larger, cage-like “host” molecule. This inclusion
can have a number of significant effects on the physical and
spectroscopic properties of the guest. One particularly useful
effect is the significant enhancement of the guest fluorescence,
which occurs for a wide range of guests, for a variety of
reasons. If the guest is an analyte of interest, then this
inclusion-induced fluorescence enhancement provides a simple,
convenient means to significantly increase the sensitivity
of its fluorescence-based trace analysis. This article will
provide a comprehensive review of the recent application of
host-guest inclusion to the spectrofluorimetric trace analysis
of a wide range of guests of interest, including pharmaceutical
and environmentally important compounds, in a variety of hosts,
including cyclodextrins and calixarenes.
[Back to top]
Application of Capillary Electrophoresis in Drug Metabolism
Studies
Jie Zhang, Jirí Konecný, Zdenek Glatz, Jos
Hoogmartens and Ann Van Schepdael
Capillary electrophoresis (CE) has been increasingly
employed for the separation of pharmaceutical agents and drugs.
This has arisen from the complementary mode of separation
afforded by CE when compared to high performance liquid chromatography
(HPLC). Qualities of CE such as high efficiency of separation,
short analysis time, remarkably low injection volume and a
variety of detection systems have facilitated acceptance of
this technology. Since different drug metabolite enantiomers
are formed in many metabolic pathways, the other indispensable
advantage of CE over HPLC is the possibility of chiral separation
without the need of special expensive columns. Recent advances
in automated systems have made CE even more popular. The focus
of this paper is to review recent studies and advances (mainly
from 2000) of drug metabolism by using CE. The review is divided
into two parts: (i) principles of CE separation of drugs and
their metabolites and (ii) application of CE in drug metabolism
studies. The first part introduces sample preparation, separation
and detection modes involved in CE drug metabolism studies.
To provide a deeper insight into the achievements, distinction
between drug metabolism analysis in vivo and in
vitro is made in the second part. Reported methods are
discussed and summarized.
[Back to top]
The Expanding Role of Mass Spectrometry in Folate Research
Bryant C. Nelson
Folate characterization has remained an important, yet complex
problem dating from the initial discovery (ca. 1931) by Lucy
Wills that yeast contained an active component capable of
curing macrocytic anemia in pregnant women. Since that time,
qualitative and quantitative analysis of folates has been
hindered by their inherent instability, multiplicity of forms
and minute levels in nature. Folate deficiency is recognized
as a serious health issue in many parts of the world, and
most recently, folate deficiency has been associated with
increased risk of developing cardiovascular disease. New,
more powerful analytical approaches, such as those based on
mass spectrometry (MS), are currently being applied to folate
characterization. Fast atom bombardment (FAB), electron-impact
(EI), plasma desorption (PD) and secondaryion MS techniques
have been used for structural characterization of folates.
Hyphenated techniques based on either liquid chromatography
(LC/MS or LC/MS/MS) or gas chromatography (GC/MS), as well
as matrix-assisted laser-desorption time-of-flight MS (MALDI-ToF
MS) and accelerator MS (AMS) have been used for folate quantitation.
A review of the past and current MS-based approaches to folate
analysis in relation to structural, nutritional and clinical
research is described in the present report. Recommendations
for future MS-based applications are also presented.
[Back to top]
Gene Expression (Microarray) Data Analysis by Chemometric
Methods
David X. Zhu, Richard J. Goeke, David L. Baker, James
H. Hamburg, David E. Booth and Stephane E. Booth
Three sets of optimal leukemia class predictors (genes) were
obtained by three different methods from three different authors
from the same set of data. We tested these three optimal sets
using back propagation neural networks (which were not used
by the original authors) with three fold cross validation
and leave one out cross validation. We found that the predictor
sets performed less well with the neural networks than with
the original methods though not in all cases. We discuss this
result and suggest methods to use in order to possibly take
advantage of this finding.
[Back to top]
Relaxation During Adiabatic Radiofrequency Pulses
Dennis J. Sorce, Shalom Michaeli and Michael Garwood
We treat in this review the general problem of relaxation
during an adiabatic radiofrequency pulses. In most of the
applications literature in Nuclear Magnetic Resonance (NMR)
the relaxation during a radio-frequency pulse has either been
neglected or avoided using the so-called “delta function
approximation” where relaxation during the short time
of the pulse is small, when the relaxations during the pulses
can be ignored. There has developed within the NMR research
community the study and use of pulses on the order of many
milliseconds where there is an explicit time-dependence in
the first rotating frame (FRF). The result of these developments
is that the time-dependence of relaxation during the radio
frequency pulse becomes important for the successful analysis
of NMR data. In this review we detail some of the theoretical
concepts for treating NMR relaxation that we have found necessary
in developing the successful fitting to data of NMR experiments
where the time dependence results from the use of adiabatic
pulses. We explicitly treat the case of identical spins ½,
then the situation of two distinct spins ½ both for
the case of the dipolar relaxation mechanism and for two site
chemical exchange.
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