Buchi DuMaster D-480 User Manual download pdf (Page 183)

Operation Manual D-480 ©BÜCH Labortechnik AG

8 - Maintaining the instrument 183

The following table explains the characteristics relating to the sample, as displayed in the above

picture:

Characteristic

Description

Sample No. Shows the analysis number of the sample selected at the cursor.

Area Integral of the selected sample.

slope Slope of the curve at the calibration point of the selected sample.

{Element name}

theo

Theoretical absolute content of the selected sample

{Element name}

act

Absolute content of the selected sample, computed with the current curve

Diff. Difference between "theo" and "act", absolute

Diff. Difference between "theo" and "act", relative

Aids for assessing the calibration curve

The following aids are available for assessing the calibration curve:

 Via View > Zoom in / Zoom out you can display the graph so that you can visually check the

curve.

 You can click on the circle to select any sample. This displays the characteristics of the sample.

 You can also select a sample using the buttons and . This displays the

characteristics of the sample.

Assessing the calibration curve

The following are used to assess the calibration curve:

 Process standard deviation "Proc-SD"

 Quality factor "r"

 Coefficient "a", that corresponds to a calibrated blank value.

Process standard deviation "Proc-SD"

Use the following values for process standard deviation "Proc-SD" as guidelines:

Acceptable value Proc-SD = ± 3 µg in the lower range

Proc-SD = ± 15 µg in the upper range

Very good value Proc-SD = ± 1 µg

Quality factor "r"

Use the following values for quality factor "r" as guidelines:

Good value for linear calibration function r = 0.99 (r should tend to 1)

Good value for polynomial as calibration

function

r = < 2-4

Coefficient "a"

Use the following values for coefficient "a" as guidelines:

Acceptable range a = 1 x 10

-3

to 3 x 10

-2

or smaller

The range given here applies to calibration with one calibration range and, when calibrating with two

calibration ranges, only for the lower range, while "a" may be greater in the second range.

If you do not approximately achieve the listed values you can assume that:

 either you have selected the wrong calibration curve calculation mode,

 or the calibration measurement has failed (weighing error, etc.).

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Buchi DuMaster D-480 User Manual Page 183

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