Hach-Lange DR 5000 brewerie analysis, supplementary software LZV570 - Manual (Page 30)

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Working procedures
• Potassium hexacyanoferrate(III), K
3
[Fe(CN)
6
], 8%: prepare
freshly each day
• Phenol standard solution:
Dissolve 1.000 g phenol in H
2
O giving 1000 ml (1ml = 1mg).
The solution must be clear and colourless. Use this solution to
prepare dilutions with which to obtain the calibration curve
between 0.02 and 0.1 mg/l when needed.
• Ammonia, dilute (1+4):
Dilute 1 part conc. ammonia (d = 0.91) with 4 parts H
2
O.
Sample preparation
1. Steam distillation
a. Introduce 50 g coarse malt and 500 ml H
2
O (for beer
analyses 300 ml) into a distillation flask.
b. Add 3 ml copper sulphate solution.
c. Add phosphoric acid until the pH is less than 4.
d. Add silicone antifoam emulsion.
e. Carry out steam distillation until 300 ml have been
obtained.
2. Colour reaction
a. Add 10 ml ammonium chloride solution to all of the
distillate (or correspondingly less in the case of genuine
smoke-dried malts or whisky malts, for example 100 ml).
To prepare a blank value solution, use 300 ml H
2
O instead
of the distillate and add 10 ml ammonium chloride solution.
b. Shake.
c. Adjust the pH of the distillate and blank value solution to
10.2 ± 0.1 by adding ammonia.
d. Transfer to 1 l separating funnels.
e. Add 3 ml 4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one
and 3 ml potassium hexacyanoferrate(III) to each funnel.
f. Shake.
g. Leave to stand for 3 min.
h. Extract by adding 10 ml chloroform to each funnel and
shaking each funnel 3 times (1 min).
i. Wait 10 min for phase separation to occur.
j. Filter the chloroform extracts through a paper filter into
25 ml measuring flasks.
k. Rinse the filters with a little chloroform.
l. Fill each flask up to the mark with chloroform.