Section 5: Instrument Maintenance
5.1 Cleaning The Cells and Pipette
Cleaning Overview
The VP-ITC uses fixed in place cells in order to provide maximum sensitivity and stability.
These cells must be cleaned routinely to maintain the high performance of the instrument. Dirty
cells will contribute greatly to cell filling problems, repeatability problems and possibly
misinterpretation of data. Inadequate cleaning is the cause of
most
problems experienced with
the VP ITC.
The importance of adequate cleaning cannot be stressed enough!
The cleanliness of the syringes must not be overlooked. This includes the injection and filling
syringes. These syringes are cleaned with the same cleaning solutions used for the cells. Be
careful not to expose the syringes to extreme temperature changes as the thermal shock could
break the glass.
Cleaning The Cells
There are three methods of cleaning the cells. The simplest is manually rinsing the cells with
buffer solution using the filling syringe. The second method involves using the cleaning device
and is detailed in
Section 3.7 Using the ThermoVac for Cleaning the ITC Sample Cell
method involves filling the cells with a cleaning solution and allowing them to soak at an elevated
temperature. The first two methods involve some physical agitation, which is necessary to
adequately clean the cells. The soaking method generally uses an aggressive cleaning agent after
the others have failed. Rinsing with water after using any cleaning agent is important.
!
WARNING:
The cells of the VP-ITC are fabricated from Hastelloy C-276, and should
never be cleaned with strong
acids
of any kind. Please consult the booklet provided on corrosion resistance of Hastelloy C-276 before
using any substances that have corrosive properties.
Reference Cell Cleaning
The VP-ITC reference cell doesn't require special cleaning but should be rinsed every week or
two using the long needle syringes.
Routine Sample Cell Cleaning
The VP-ITC sample cell need not be cleaned with detergent solution after each experiment, since
rinsing with water or buffer from a syringe is often adequate. However, after every 3-5
experiments (or at the end of each day’s experiments) solids that cannot be removed by rinsing
may adhere to the cell interior and these can cause baseline problems if not removed periodically
by a thorough cleaning with detergent solution.
For routine cleaning prepare a 5% solution (v/v % with distilled or deionized water) of Contrad-
70
1
at room temperature. Using the glass needle cell filling syringe enter the solution into the
sample cell and allow to sit for 10-15 minutes.
1
Contrad-70 (referred to as Decon-90 in Europe), manufactured by Decon laboratories, contains
dodecylbenzenesulfonic acid, potassium hydroxide, sodium citrate and sodium laurel ether sulfate.
Sources: Decon Laboratories, Bryn Mawr, PA 19010 USA - 1.610.520.0610 – Decon Catalog # 1003
Thomas Scientific, P.O. Box 99, Swedesboro, NJ 08085-0099 - 1.609.467.2000 -Thomas Cat. #2901-C30
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