Research
in the Frederick group focuses on developing new laser-based instrumental
methods. Our research falls into two basic areas: forensic applications
of Raman microspectroscopy and characterization of surface interactions
in capillary electrophoresis. Students involved in this work will
gain experience constructing instruments, interfacing computers
and instruments, working with optics and lasers as well as investigating
the complications associated with complex samples.
Forensic
Science Applications of Raman Microspectroscopy
Raman microspectroscopy is well suited to studying
samples which might be of interest in legal proceedings because
the sample remains unaltered after analysis allowing the same piece
of evidence to be tested and re-tested. In addition, because our
instrument uses a microscope, we can study small and/or heterogeneous
samples. One project which is currently under investigation in my
lab involves characterizing and quantifying simulated street drug
samples which are heterogeneous mixtures of cutting agents and non-pharmacologically
active drug surrogates. Other research projects involve identifying
lipstick smears on paper and glass, assessing the feasibility of
Raman spectroscopy to differentiate between different types and
brands of perfume and studying burning and aging of carpet fibers.
Characterization
of Surface Interactions in Capillary Electrophoresis
Electroosmotic flow is used in microchannel devices
to control nano-scale reactions or separations. This technology
is known by other names such as "lab on a chip" or "micro-total
analytical systems (micro-TAS) and is seen by many as the future
of analytical and biochemical assays. Therefore, understanding and
modifying electroosmotic flow (EOF) is a critical area of research
in capillary electrophoresis and microfabricated devices. Because
the magnitude of EOF is dependent on the chemistry at the interface
between the capillary surface and the solution, it is sensitive
to pH, ionic strength, temperature and adsorption of chemical species.
Of particular concern in biochemical separations is the tendency
of hydrophobic proteins to adhere to the capillary wall. Research
in the area of capillary coating materials which modify EOF and
prevent analyte interactions with the capillary wall has been actively
pursued by many groups. Regardless of the coating material and procedure,
magnitude of EOF is the principal method used to evaluate degree
and/or success of the method. Unfortunately, no protocol is currently
available for simply and quickly measuring EOF in coated capillaries
in real time and no procedure is available for studying EOF during
the coating process. Research in the Frederick group involves using
an optical flow monitoring method to measure EOF for the purpose
of studying coated capillaries and capillary coating procedures.
This work is currently supported by Research Corporation and the
National Science Foundation.
