PlasmaQuant MS product family
Detector calibration
89
Prepare two detector calibration solutions, i.e., Solution A and Solution B, which
must contain all the analytes of interest. Solution A is used to calibrate the medium
attenuation factor, and Solution B is used to calibrate the high attenuation factor.
To avoid possible detector over-range, it is recommended that the concentration
for Solution A be around 1 µg/L and the concentration for Solution B be 50 µg/L.
The solution concentration levels for specific analyte/s may vary depending on the
sensitivities and the background interferences. A lower concentration may be
required for a given isotope/analyte with higher sensitivity or higher background,
and vice versa, a higher concentration may be needed for an isotope with lower
sensitivity.
9.3
Detector calibration worksheet
To perform a detector calibration, you must use/create a worksheet that is specially
designed for the detector calibration task. There is a specific detector calibration
worksheet, named D
ETECTOR
C
ALIBRATION
T
EST
.
MSWS
, supplied with the software (in the
Supplied Worksheet folder). This worksheet, however, only calibrates the attenuation
factors for the isotopes/elements presented in the standard tuning solution. You can
either modify this worksheet to your needs or create a new detector calibration
worksheet.
The following describes some key steps on how to create a detector calibration
worksheet. Refer to the software help for details about creating/developing a new
ASpect MS worksheet.
Most users measure other elemental isotopes that are not in the supplied worksheet.
To do this, you must create a worksheet to use in the detector calibration routine; it
should contain all the same isotopes as those intended to be used in a worksheet
analysis of unknown samples. One way to simplify the process of creating a suitable
worksheet is to create a worksheet that is intended to be used for analysis. After that
worksheet has been created successfully and is in a semi-final “ready to run” form (that
is, the worksheet is ready to run, except that the attenuation factors are missing), then
make a copy of this worksheet (Save As).
The reason for making a copy and using the copy for the detector calibration routine is
because worksheet settings need to be slightly different for this routine than those in
the worksheet that is used for analysis. A worksheet intended to be used for detector
calibration must be checked (and modified if required) so that only one isotope should
be chosen per element entry in the E
LEMENT
page of the M
ETHOD
E
DITOR
.
For example, by default, three isotopes are selected for lead; only one should be
selected per each line entry for calibration of the attenuation mode. Refer to the
screen capture below, which shows a correct entry for multiple isotopes of lead. This is
because factors need to be determined on a per mass basis.