Glossary of Terms 169
P/N CLS151164 Rev. B LabChip GX Touch/GXII Touch User Manual PerkinElmer, Inc.
DNA Assay Analysis
DNA samples contain two marker peaks outside the limits of the
DNA fragment sizes the assay is designed to detect. The ladders
contain the same two marker peaks. The sample data is aligned to
the ladder data by matching the peak times of the two markers in
the sample data with the same two markers in the ladder data. The
size of each sample peak is calculated by linear interpolation
between the known ladder peak migration time and size using the
peak aligned migration time. The analysis settings can be changed
in the LabChip GX Reviewer software to perform the interpolation
using a local third order polynomial fit to the time instead of the size
relationship provided by the ladder.
The concentration of the sample peaks is calculated using the
known area and concentration of the ladder peaks. The molarity of
each sample peak is calculated using the sample concentration, the
DNA fragment size (in base pairs) attributed to the peak, and the
known molecular weight of the DNA base pair.
Electrokinetic Forces
Electrokinetic forces are used to move, switch, mix, and separate
the nucleic acid samples. Active control over voltage gradients
directs the movement of materials using the phenomenon of
electroosmotic flow or electromigration.
Electroosmotic Flow
A phenomenon that results from an electrical double layer formed
by ions in the fluid and surface electrical charges immobilized on
the capillary walls. When an electric field is applied, the bulk
solution moves towards one of the electrodes. This phenomenon
can be used to move fluids through microfabricated channels
Electrophoresis
A technique of separating molecules on the basis of their mobility.
An electrical potential is applied across a capillary containing a
sample in a fluid medium. Positive molecules migrate towards the
cathode and negative molecules migrate towards the anode at
different speeds depending on their electrophoretic mobility.
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