NEW BRUNSWICK SCIENTIFIC BioFlo 415, Manual To Operations

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BioFlo 415
y
M1360-0050 User’s Guide
Take note that silicon tubing should not be used with hydrochloric acid (HCL),
sulfuric acid (H2SO4)) or sodium hydroxide solutions since this material deteriorates
rapidly when in contact with such solutions. Another reason for avoiding HCL is that
HCL (and to a lesser extent H
2
SO
4
) causes corrosion of stainless steel. NaOH
solutions equal to or less than 20% can be used in silicon tubing at temperatures less
than 120
°
F without destroying the tubing. Solutions of sulfuric acid less than 10%
can cause moderate damage to silicon tubing.
23.4 Acid & Base
Question: What concentration and type of acid and base should be used?
Answer:
The acid solution is 2 - 3N H2SO4. The base solution is either
5N NaOH or NH4OH ~ 29% (which is the standard commercially available
concentration.) Note that these are fairly concentrated. The acid can affect the
stainless steel parts of the fermentor vessel. To avoid damage to the entry ports, it is a
good idea to use a sterile, disposable needle at the end of the addition tubing and to
add the acid (or base) through the disposable needle. The needle will corrode, but it
saves the fermentor vessel. Insert the needle though a septum port so that the drip
point is away from stainless steel components and fairly close to the liquid level. You
may also use a more diluted solution of the acid or base. However, take note that this
may cause the complication of adding a larger volume of liquid to the vessel. Also, it
is not a good idea to add acid and base through a single double or triple port adapter.
The combined effects of both causes rapid corrosion of the adapter.
The pump setting is usually 20.0 - 25.0 under acid or base mode. For these
concentrations of acid and base, Marprene tubing should be used. If you are using
silicon tubing, reduce the concentration of H
2
SO
4
to less than 8% (about 5%) and use a
20% solution of NaOH. When selecting an acid for use in fermentation, select the
lowest possible concentration that allows for pH control.
23.5 Glucose Feed
Question: What is the proper concentration of glucose feed?
Answer:
The glucose is 50% concentration. The feed rate is not usually a constant
value as this will differ not only from run to run, but it will vary greatly over the
course of a run, depending upon the organism's growth. This operation can be
controlled automatically by
BioCommand Plus
, NBS' proprietary Windows
®
-based
software.