High performance capillary electrophoresis - T.E.A.M.

where
DP = pressure difference across the capillary
d = capillary inside diameter
t = time
h = buffer viscosity
L = total capillary length
Typical injection pressures and times range from 25 to
100 mbar and 0.5 to 5 s, respectively. Using equation (28),
the sample plug volume and length loaded, as a function of
applied pressure, time, and capillary dimensions, is given in
table 16.
Injection 10 µm 25 µm 50 µm 75 µm 100 µm
pressure V p
I p
V p
I p
V p
I p
V p
I p
V p
I p
x time, mbars (nl) (mm) (nl) (mm) (nl) (mm) (nl) (mm) (nl) (mm)
Instrumentation/Operation
Table 16
Injection volume and plug length as a
function of pressure, time and capillary id
25 0.0008 0.01 0.03 0.06 0.5 0.25 2.6 0.59 8.2 1.04
50 0.0016 0.02 0.06 0.12 1.0 0.50 5.2 1.18 16.4 2.08
75 0.0024 0.03 0.09 0.18 1.5 0.75 7.8 1.77 24.6 3.13
100 0.0032 0.04 0.12 0.24 2.0 1.00 10.4 2.26 32.8 4.16
150 0.0048 0.06 0.18 0.36 3.0 1.50 15.6 3.54 49.2 6.26
V p
= plug volume L = 75 cm h = 1
I p
= plug lengths T= 25 °C
For siphoning injection, the pressure differential for use in
equation (28) is given in
DP= rgDH (29)
where p = buffer density
g = gravitional constant
Dh = height differential of the reservoirs.
A typical siphoning injection is obtained by raising the
sample reservoir 5 to 10 cm relative to the exit reservoir for
10 to 30 seconds, depending on the conditions. Siphoning is
typically used in systems without pressure injection capabilities.
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