Buchi DuMaster D-480, Руководство по эксплуатации

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Operating instructions DuMaster D-480 ©BÜCHI Labortechnik AG
4 - Understanding the instrument and planning its use 56
Conditioning samples
Conditioning samples are measured with standard substances at the start of every series of analyses.
They are used to check...

... the correct run of the analysis.

... the proper condition of the instrument.

... flow and pressure behavior of the gases.
Daily factor determinations
Determination of the daily factor serves...

... to fine-tune instrument calibration to room conditions at the time of analysis.

... to assess the condition of the instrument by observing daily factor fluctuations and drift trends.
When to perform routine measuring work
Perform routine measuring work...

... at least once a day.

... additionally when measuring breaks last longer than 2 hours.
If a series of analyses exceeds a duration of 5-6 hours (carousel completely loaded), it is advisable to
determine the daily factor additionally at the end of the series.
Formulae for blank value determination and compensation
Blank samples and blank values
Blank samples are samples...

... that do not contain sample substance.

... that have a key word for identification by the software as blind samples.
Despite the lack of sample substance, a peak area value is computed on the basis of various factors
when analyzing blank samples. This peak area value is referred to as a blank value. In order to
compensate for this, the averaged blank value is subtracted from the measured peak area value of
every individual analysis sample.
Blank value determination
In blank value determination, the peak area values of the blank samples are averaged. The blank
value is computed according to this formula:
where:
/b = blank value
b
i
= peak areas of the individual blank samples
n = number of blank samples
i = index from 1 to n
Blank value compensation
The peak areas of the other samples are compensated with the aid of this formula:
where:
a
comp
= compensated peak area
a = measured peak area of the sample
/b = blank value