Section 5: Instrument Maintenance
temperature drops. Top Job is a general purpose ammoniated household cleaner consisting of
ionic and non-ionic surfactants. The cells are then extensively rinsed and drained.
Detergent Wash:
The cleaning device is used as described in
Section 3.7 Using the ThermoVac
for Cleaning the ITC Sample Cell
(page 47). 200-400 ml or more of detergent solution is passed
through the cells. 300 ml or more of water is then passed through the cells to rinse the detergent
out.
Detergent Soak:
The cells are filled with a detergent solution such a 5% V/V aqueous Contrad-
70™ solution. The cells are not capped but covered with a damp paper towel. The thermostat
temperature is then set to 65
°
C for one hour. The cells are then cooled and rinsed with 300 ml or
more of water using the cleaning device. Do not exceed one hour unless advised by a MicroCal
engineer to do so.
Base Soak:
This is an extreme measure and should
only be preformed after consulting with a
MicroCal engineer or representative and should not be preformed on a regular basis. The cells
are filled with a 12% solution of sodium hydroxide. The cell is covered with a damp paper towel
placed over the cell port. The system is then thermostatted at 65
°
C. for one hour. The system is
then cooled and rinsed with water using the cleaning device.
Cleaning Agents
Your choice of cleaning agents will vary with the cell contamination. Below is a partial list of
several agents and their applicability.
Top Job (Mr. Clean):
Is manufactured by
Procter and Gamble and is available in many
supermarkets.
Dawn Dishwashing Detergent.
Also Manufactured by Procter and Gamble and is available in
many supermarkets. It is used as a mild protein cleaner.
Contrad-70:
An excellent biological cleaner for a wide variety of contaminations. It is
biodegradable and easily rinsed. This solution is an excellent agent for the VP ITC
Pepsin (.1% solution):
Used as a soaking agent to digest difficult protein problems.
EDTA (10% solution):
Used as a post cleaning rinsing agent to eliminate metal ion
contamination.
Organic Solvents:
Methanol, hexane, toluene and other solvents are used to remove lipid and
some polymer contamination.
A Word of Caution
Careful consideration should be put into the selection of a cleaning program. As mentioned previously
the cells of the VP ITC are constructed of Hastelloy. Hastelloy is highly resistant to attack from bases but
not from acids. Care should be exercised to avoid damage to the cells.
If the reservoir should overflow during your cleaning procedure, the fluid may contaminate the stir motor
bearing and damage it beyond repair. This must be avoided! If an overflow does occur, the injector
should be removed and the bearings on the underside should be wiped dry. If internal contamination is
suspected, you should consult with a MicroCal engineer for assistance.
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