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5.2.3
Sterilization
If your application requires aseptic monitoring, all tubing and connectors should be sterilized (autoclaved)
prior to use. The tubing, connectors and pump head should be assembled, the open ends of the tubing
should be clamped off (two clamps are provided) and the entire assembly (tubing with pump head) should
be sterilized along with the bioreactor.
If the tubing is connected to the bioreactor after sterilization, a
sterile connection must be made.
After sterilization the pump should be remounted onto the 2700. Refer to Section 8.1, Tubing
Replacement, before installing the tubing in the solenoid valve. The antiseptic cycle must be enabled (see
Section 5.2.1) and the antiseptic solution must be primed immediately after the tubing is reconnected (see
Section 5.3.1).
The 2730 may be used for process monitoring and/or control applications without the use of an antiseptic.
Refer to Section 5.2.1.
5.2.4
Make-Up Cycle
The make-up cycle occurs after the 2730 has pumped sample from the sample source for the user
programmed amount of time and the sipper is ready to aspirate. At this point, the solenoid valve switches
to the antiseptic position and the monitor pump flow rate changes from the user programmed rate to
approximately 580
µ
L per minute. This prevents the sipper from drawing all the sample out of the external
chamber and aspirating air. If the antiseptic cycle is disabled by the user, the solenoid valve still switches
to the antiseptic position and air or fluid is pumped through the antiseptic line during the make-up cycle.
The antiseptic line must be kept free from obstructions even if the antiseptic cycle is not used. A dry 0.2
micron filter may be inserted upstream from the solenoid valve to prevent contamination in the air from
entering the antiseptic line during the make-up cycle.
Warning: The antiseptic line must not be blocked off even if
the antiseptic cycle is disabled.
5.2.5
Autocalibration
In addition to setting monitoring parameters, you may want to consider your calibration strategy. In
default settings, autocalibrations are programmed to occur after every 5 samples or every 15 minutes,
whichever occurs sooner. Autocalibrations are also initiated if the temperature drifts more than 1°C in the
chamber housing the enzyme electrodes, or if the calibration current shifts by more than 2% from a
previous calibration, or if one of several sample errors (e.g., unstable baseline) is detected. However, all of
these parameters can be changed or disabled.
The Autocalibration Parameters are listed below. Refer to the YSI 2700 SELECT USER’S MANUAL,
Section 5, Menu Selections for more detail.
•
Temperature........Degrees C drift between calibrations
•
Time....................Time in minutes between autocalibrations
•
Sample ................Number of samples performed between autocalibrations
•
Cal Shift..............Precision as % compared to previous calibration
•
Sample Error.......On/Off to detect errors related to system problems
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