Hach-Lange DR 5000 brewerie analysis, supplementary software LZV570 - Manual (Page 47)

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Working procedures
2.12.1.1 Executing the test with the sipper module
Information about the installation, module configurations and
sample introduction of the sipper module can be found in the user
manual of the DR 5000 Spectrophotometer (15.3.3. Installation
Sipper Module, page 133).
Obtaining the calibration curve
The factor 1 = 0.037 is an empirical variable and has to be
individually determined from a calibration line. The factor is the
gradient of the calibration line.
• Pipette 40 ml beer into each of four 50 ml measuring flasks.
• Pipette respectively 0.40 ml, 0.80 ml, 1.60 ml and 3.20 ml iron
standard solution (5 mg Fe
3+ /ml) into the measuring flasks.
• Add 2 ml Ferrozin reagent and 1 ml ascorbic acid solution to
each measuring flask.
• Make up to the mark with H
2
O.
• Measure the absorbance of the solution in a 40 mm rectangular
cuvette at 560 nm against the corresponding blank value
solution.
Deduct the absorbance of the sample from the absorbance values of the
standard solutions.