4 - Setting Up the XLP 6000 for Your Application
Optimizing XLP 6000 Performance
Cavro® XLP 6000 Modular Syringe Pump Operating Manual, 734237-C, en
4 - 7
should be slow (to avoid cavitation) and dispense fast (to promote breakoff).
Since cavitation and breakoff will affect both accuracy and precision, speed
settings may be optimized separately for aspiration and dispense.
Using aspirate/dispense commands, set start speed [v] and top speed [V] to
meet application throughput goals.
–
Send the command [v50IA6000OA0R]. Repeat with increasing start
speed (increase “v_” value) to find the maximum value.
–
Send the command [v
x
V
x
IA6000OA0R] to set top speed equal to start
speed (
x
). Repeat with increasing top speed (increase “V_” value) to the
maximum value that does not overload the plunger or cause cavitation.
Now optimize start speed and top speed for dispensing using a similar
approach.
10
Set cutoff speed and slope.
Using aspirate/dispense commands, set slope [L] and cutoff speed [c] to attain
reproducible breakoff. Note that cutoff speed controls only dispensing.
To optimize the slope, send the command [v
x
V
x
L14IA6000OA0R]. Repeat
with modified slope (“L_” value) to achieve the overall time suited to your
application without plunger overload.
To optimize the cutoff speed, start with the maximum cutoff speed allowed for
your application (the lower of 2700 Hz or the top speed). Send the command
[c
x
IA6000OA0R] and monitor the dispense for plunger overload or any
splattering of the fluid dispensed outside of the dispense vessel. If any of
these conditions occur, lower the cutoff speed until the pump can dispense the
fluid with clean breakoff.
Another condition that affects breakoff is the formation of inertial air gaps. This
is seen as a small air gap inside the tubing at the tip. This occurs to a greater
extent on larger reagent syringes, and it enhances the breakoff of liquid from
the tip of the tubing. If an inertial air gap is not desired in the application,
lowering the cutoff speed and/or the top speed will remove the inertial air gap.
However, this may not give a clean breakoff of the fluid.
In some instances it may not be possible to improve fluid breakoff. Clean
breakoff is important to accuracy and precision; it is a concern especially
when using slow speeds because drops will usually adhere to the tip.
For example, using a 2.5 mL reagent syringe (P/N 5133, dispense tubing and
de-ionized water with a surfactant added):
–
[S24IA6000OA0R] - will leave a drop on the tip
–
[S24IA6000OA5S1A0R] - no drop will be left
–
[V100IA6000OA0R] - will leave a drop on the tip
–
[V100IA6000OA5V5500A0R] - no drop will be left
Increasing the cutoff speed and ramp (slope) may also improve the fluid
breakoff. Smaller I.D. tubing may improve breakoff, especially for smaller
syringes.
Note: It may not be possible to achieve good fluid breakoff under any
circumstance, especially with syringes smaller than 500 µL or with some fluids.
