Metrohm 754 Dialysis Unit - Manual (Page 30)

3.3 The dialysis procedure
754 Dialysis Unit
27
2 Measure the standard with dialysis
• Set the dialysis time in the program to 5 min (see section
3.3.2).
• Immerse sample suction tubing 26 26 in the standard used in
point 1.
• Start the program on the 732 IC Detector with the <PROG
R/S> key. Wait until the LED in the <PROG R/S> key stops
flashing, signalling the end of the evaluation.
3 Additional measurements
• Increase the dialysis time in the program (see section 3.3.2)
by 5 min increments until the measured values remain con-
stant.
• Take measurements as per point 2.
4 Determine optimum dialysis time
• Record the ratio of the peak surfaces, i.e. concentrations
measured with and without dialysis in relation to the dialysis
time (i.e. the recovery rate) and determine the optimum dialy-
sis time.
3.3.6 Setting the program time
Set the program time so that the chromatogram can be completely re-
corded and evaluated within this period.
3.3.7 Dialysis procedure
To analyse samples using dialysis you should preferably proceed as
follows:
1 Prepare acceptor solution
• To avoid malfunctions caused by air bubbles in the acceptor
channel, the ultrapure water used for the acceptor solution
should always be degassed for at least 10 min with vacuum,
N
2
or He.
2 Prepare sample
• To prevent blockages in the sample channel, samples con-
taining a high volume of (suspended/solid particles) should
always be centrifuged using a table centrifuge at 10,000
rev./min for 5 min.