Buchi DuMaster D-480 Instrukcja Użytkownika Pobierz pdf (Strona 138)

Operation Manual D-480 ©BÜCH Labortechnik AG

7 - Using the instrument 138

Animal feed, approx. 500 mg medium fat content 50 mgFeed 250 ml/min, 100 sec

Cheese, sausage, appr. 500 mg high fat content 500fatCheeseSausage 300 ml/min, 150 sec

Blank value with O

Blank with O2 80 ml/min, 60 sec

Blank value without O

Blank without O2 50 ml/min, 1 sec

Beer, milk, soil, appr. 500 mg medium fat content 500mgBeerMilkSoil 120 ml/min, 60 sec

Starch, approx. 400 mg 400mgStarch 250 ml/min, 150 sec

Soil, approx. 250 mg 250mgSoil 100 ml/min, 60 sec

Optimize O

dosing

If your sample matrix is always the same, it is advisable to optimize oxygen dosing for reasons of

costs. Proceed as follows:

 Measure a typical sample of known element content several times with the same sample weight

(max. ± 2 mg fluctuation).

 Systematically increase O

cut off threshold until you get a false low reading or a substantial

widening of the N peak.

 Set the O

cut off threshold of the last successful measurement before the false low reading

occurred. These settings are optimal for this matrix and sample weight.

 Check whether oxygen dosing is generally usable. To do so, measure several known samples of

similar matrix.

Example for optimization of oxygen dosing

cut off threshold = 30 %, total O

amount = 589 ml

cut off threshold = 40 %, total O

amount = 478 ml

Performing measurements

What you need to know

You must have read the Oxygen dosing values (on page 137) section so that you can set the

correct values for measuring.

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Buchi DuMaster D-480 Instrukcja Użytkownika Strona 138