Standard for error correction

Overview

The Standard for error correction (previously named internal standard) functionality allows you to correct peak heights/areas in an evaluation by:

  • Defining a substance of the evaluation as Standard for error correction. This standard for error correction should be defined on each track, have the same quantity applied across all tracks and be known to behave similarly to the other substances defined in the evaluation in order for the standard for error correction to make sense.

  • Computing, for each track, the deviation of the peak height/area of the standard for error correction on this track compared to the average peak height/area on reference tracks.

  • For each peak of each other substance, applying the inverse the deviation (i.e. correcting) computed for the track where the peak is assigned.

Defining the standard for error correction

../../../_images/standard_error_correction_definition.png

In the Definition tab of the evaluation, use the Advanced options (A) button to make the Standard for error correction (B) field appear. In an evaluation, there can be only one standard for error correction. Because the standard for error correction is not itself calibrated, its calibration-related fields are hidden.

During the calibration

During the Calibration phase, displaying the standard for error correction substance makes a table appear where the measured deviations are shown for each track.

../../../_images/standard_error_correction_calibration.png

For each reference track (here, the tracks from 3 to and 7), the average height and area of the assigned peaks for the standard for error correction are computed and shown on the top information box (here, 0.2499 and 0.0058 respectively). The Deviation columns show the relative difference of the peak height/area compared to the average peak/area. For example, the track 3 had a peak height of 0.2495, which is 0.16% lower than the average height 0.2499. Therefore, all other assigned peak heights on track 3 should be corrected by 0.16%.

The Allowed deviation box defines a maximum deviation for the standard for error correction. If a deviation exceeds the limit, then the standard for error correction fails and no results are computed at all for the whole evaluation.

When displaying another substance, the tooltip gives the details of the standard for error correction:

../../../_images/standard_error_correction_calibration_tooltip.png

Here, the measured height of the peak was 0.2485, the correction to apply was 0.16%, therefore the peak height considered is 0.2489. Of course, the calibration curve is then computed by using the corrected reference points and the corrected sample points are used to deduct the resulting quantity and concentration.

In the results

The Results tab simply shows an information text indicating the correction with an standard for error correction, if any.