Beckman Coulter Multisizer 4, User Manual

Page: 70 / 238

PN A51387A
B
3-16
Installing and Calibrating an Aperture Tube
Calibrating the Aperture
NOTE
If this is the first calibration run, the Old Kd value is assigned an estimated value based on
aperture size.
a. Click
(
Find Peak
)
to place cursors at or on either side of the peak of the calibration graph.
If you are performing a modal calibration, clicking
(
Find Peak
)
automatically places a
cursor on the modal channel. If you are performing a mean calibration,
(
Find Peak
)
automatically places two cursors on the graph, one on either side of the peak. The cursor(s)
define the mode or median used to calculate the new Kd.
b. Click
(
Print
)
to print the window. This button does not display a dialog box or allow you to
change print settings.
c.
In the Use New Kd for pane, select an option to use the new Kd for the next analysis run
only, all subsequent runs, or to update the aperture list.
d. Click
(
Accept New Kd
)
to enter the new Kd and close the window.
NOTE
When you calibrate the aperture, the Multisizer 4 runs an analysis to measure calibrator beads
of a predetermined size (ranging from a nominal modal value of 2 µm to 90 µm). Deviations in
the Analyzer’s measurement of the calibrator beads determine the calibration constant (Kd)
required for the Analyzer to measure the beads at their actual size.
The Kd takes into account many factors associated with the instrument and the aperture tube,
including fluid flow characteristics, electrical resistance with the electrolyte, and imperfections
of the orifice such as chip damage or wear.
Obtaining the Mean Kd
For consistent results, perform the aperture calibration procedure at least 10 times and calculate
the mean calibration constant (Kd). In future calibration runs, the Kd should be within 4% (+ or -) of
the mean Kd value.
To obtain the mean Kd:
1. Calibrate the aperture.
2. Record the Kd value.
3. Repeat the calibration procedure nine times until you have 10 Kd values.
4. Add the 10 values and divide by 10 to obtain the mean value.
NOTE
The mean Kd value is valid only for the aperture tube, electrolyte, and Analyzer combination
used for the calibration.