Who am I
Analytical Chemistry Webbed
The Barnett Institute
Dept. of Chem. & Biochem. at
Texas Tech University
An Integrated LC/MS/UV/ELSD/CLND System for Combinatorial Chemistry
Devices for Multiple Channel Electrospray Mass Spectrometry
How to achieve high throughput, small sample requirement, low cost,
lack of cross contamination? Multiple channel plastic devices which are
interfaced to a mass spectrometer could be one of the feasible approaches.
We developed an automated high throughput (720 samples/hr) ESI-MS system
based on a microfabricated platic 96-well plate to which 96 channels and
96 ESI tips are incorporated. The feasibility of the system has been demonstrated
through the high throughput analysis of peptides and proteins as well as
IC50 determination in HIV-1 enzyme inhibition assays.
Other type of microfabricated plastic devices
have also been tested.
The inlet of a capillary is joined to an open stream of buffer formed on
an inclined narrow surface and a constant voltage is applied to the capillary.
A drop of sample falls directly to the capillary inlet and then is washed
away quickly. Thus, a short sample plug with limited dilution by the stream
of buffer is injected in electrokinetic mode. No moving parts are involved
and no adjustment of voltage is necessary in the injection process. The
method is simple, reproducible, easy to automate and should prove to be
a valuable complement to the present injection techniques for capillary
A micro (~0.0013 mL) organic drop is suspended inside a flowing aqueous
drop from which the analyte is extracted. The aqueous phase is continuously
delivered to the outer drop and is aspirated away from the bottom meniscus
of the drop. After the sampling/extraction period, a wash solution replaces
the sample/reagent in the aqueous layer, resulting in a clear outer aqueous
drop housing a colored organic drop containing the extracted material.
This also results in an automatic backwash. The color intensity of the
organic drop, related to the analyte concentration, is monitored by a light
emitting diode (LED) based absorbance detector. After the analytical cycle,
the organic drop is removed and replaced by a new one. This unique micro
extraction system is simple, flexible, permits automated backwashing, consumes
only micro quantities of organic solvents and is capable of being coupled
with other analytical systems. This concept should prove valuable for preconcentration
and matrix isolation on a micro scale.
Like to see more drops? Please go to
Analytical Chemistry Systems Using Liquid Drops