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Online Worksheet Notes
How to use Drift Correction, single point
Issue
The primary factors limiting accuracy and precision using Inductively Coupled Plasma Mass
Spectrometry (ICP-MS) in matrix-matched external standardization are machine drift and
variation of the instrument response as a function of mass. In this case we assume the drift is
linear and changes proportional to the time and the sampling. An analytical procedure and an offline
data reduction algorithm have been developed which correct for these variations and
produce a significant improvement in analytical accuracy and precision. In this technique, a 'drift
correction' standard is analyzed after every group of samples (5 recommended).
The drift correction is calculated from the QC Drift Correction values: Insert diagram


Insert Diagrams & text from P2, 3 4 & http://www.online-lims.com/download/note_drift_correction.pdf


Online Worksheet includes two Drift Correction tools
1. Drift Correction, where only one DC-QC is used through the run
2. Two point drift correction, where two DC-QC’s are used through the run. This
method is not discussed in this note.
In order to run the drift correction, the Worksheet file needs to be configured in a predefined
format. The worksheet needs this format to know from where to load the DC-STD (Drift
standard sample) and the subsequent DC-QC (Drift QC samples).
Configure a worksheet where the DC-STD (Drift standard) is on the first row. The DC-STD
should start with a ‘~’ character (NOS: non-sample flag).
Column inserted by
the DC tool
Drift QC
standard
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The column header (Test ID’s) where the drift correction should be applied must have the ‘-DC’
suffix. When importing large batches from an ICP run, use the Test ID suffix from the import
dialog, as shown in the figure below. When running the DC a column is automatically inserted to
the right of the column identified with the ‘-DC’. The new column ID will have a ‘-COR’ suffix
and this column will include all drift corrected data.
All subsequent DC-QC (drift control samples) should match exactly the DC-STD entered in the
first row of the worksheet but without the ‘~’ character. We recommend inserting a DC-QC each
5 samples to get a higher precision.
Conclusion
The advantage of the drift correction tool is that the data accuracy is improved after the run,
saving a lot of time on ICP’s runs. Because the DC-column is inserted right beside the
instrument source data column, the technician is free to decide how to proceed.
The next screen shot shows a worksheet after the classical drift correction has been applied to an
ICP run.
Suffix that identifies towhich column the DCshould be applied