Difference between revisions of "Talk:Oxygen flux - instrumental background"
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=== Troubleshooting === | === Troubleshooting === | ||
Ticket#2020040710000012 | Ticket#2020040710000012 (I knos that this need to get out, just to remember): | ||
The customer have a background file with a drop on O2 slope neg. after event P003 right in the place that usually is made the mark, as showed in the figure below resulting in a lower intercept (a<sup>0</sup>) of -5.5782: | The customer have a background file with a drop on O2 slope neg. after event P003 right in the place that usually is made the mark, as showed in the figure below resulting in a lower intercept (a<sup>0</sup>) of -5.5782: | ||
Revision as of 12:37, 28 April 2020
Intercept (a0) for high oxygen backgrounds
What does the intercept (a0) for high oxygen backgrounds actually mean? Can it be used as a quality control parameter?
Unlike for the situation of backgrounds spanning atmospheric saturation to low oxygen, in high O2 backgrounds the data point with the lowest oxygen concentration is far removed from the y axis . So while the two parameters intercept and slope describe the background adequately for correction the descriptive value of the intercept alone is rather small. (Basically the regression line can be rotated slightly without much effect on the calculation in its valid range - but the intercept will be shifted drastically by this slight rotation.) Considering your very high O2 level I also think that your values are not that unusual. If you want me to have a look on the files please feel free to send them. If there is a suspicion that the chamber is leaky you could record a background at standard conditions - any problem of the chamber should also be visible in such a background. So one could express it in the following way:
- Instrumental oxygen background covering the range from atmospheric saturation to low oxygen is BOTH: A way to determine the background parameters and a very powerful instrumental performance test, checking (inter alia) for too high back diffusion, visible in the obtained background parameters.
- Instrumental oxygen background at high oxygen levels is a way to determine the background parameters. Very massive problems in back diffusion will also be detected.
Fasching Mario 09:48, 31 January 2014 (CET)
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Troubleshooting
Ticket#2020040710000012 (I knos that this need to get out, just to remember):
The customer have a background file with a drop on O2 slope neg. after event P003 right in the place that usually is made the mark, as showed in the figure below resulting in a lower intercept (a0) of -5.5782:
Answer: For instance, if you see after the event P003 the mark J°4 is set on a non stable signal that can happen due to oxygen back diffusion, which occur when the TIP2k-Filter papers (meant to soak up any extruded liquid during the instrumental background correction) have moved within the stopper. I would make the mark on the more stable signal before the drop and but is always better repeat the background. Additionally, it is better if you analyze it using the layout 02-Calibration Background which will help you to choose more stable marks.
