Selecta 4002627, Руководство пользователя

Страница: 34 / 48

INSTRUCTION MANUAL CODE 80187 REV D 01/2021 Page: 34
J
.P. SELECTA s.a.u. Autovía A-2 Km 585.1 Abrera 08630 (Barcelona) España Tel 34 937 700 877 Fax 34 937 702 362
e-mail: selecta@jpselecta.es - website: http://www.grupo-selecta.com
6 Sample distillation
To get good analysis’ results and a good performance of the distiller it is suggested to
follow a working routine.
6.1 Check levels of tanks
Before starting a batch analysis, check the following levels:
Steam generator water tank level
Refill it with demineralised water.
If the conductivity is low, add about 50mg of Salt (NaCl or Na2CO3) per 10 L. of water.
The water reservoir is 6 litres capacity, enough for analysing more than 20 samples.
Level of NaOH
Refill with NaOH 40% from the 2 litres flask. It is placed inside the unit.
Get the NaOH flask from the door placed on the left hand side cover.
The NaOH solution must be free of ammonia salts, to avoid its interference on the
result.
Boric acid preparation
Prepare enough quantity of Boric acid 4% with mixing of indicators. Remember that
a volume of 50 ml will be used on each distillation.
Tritation reagent preparation
Prepare enough quantity of tritation reagent, usually HCl or H
2
SO
4
0.25 Normality.
Note: See chapter 7 about the reagents.
Note:
The precision of the results are affected directly by the precision of the acid
normality used for tritation. This is a common cause of error , because, along the
time, opened bottles tends to increase its normality.
Also, often there are errors in concentration calculation to prepare the acid for tritation.
6.2 Unit warm-up.
In order to get the best results with your Kjeldahl distiller, you have to run a warm-
up step before starting samples’ analysis. For it just insert a sample tube with 25ml
of clean water and let distillate around 5 minutes. (Put an Erlenmeyer flask on the
cooler output)
Run also this warm up, if the unit has been 2 or 3 hour without working.
Almonds 5,18
Nuts 5,30
Nut-peanuts, nuts Brazil 5,41
Jello 5,55
Soya 5,71
Cebada, avena, centeno 5.83
wheat, whole flour 5,83
Flours (except the whole) 5,70
Rice 5,95
Corn 6,25
All the other foods 6,25
Saved 6,31
Milk and milky products 6,38