Velp Scientifica
– UDK139 Operating Manual
10004762/B5
81
11 - Kjeldahl method to determine the protein content on canned
cat/dog food
Procedure
1) Sample:
homogenize the sample by a suitable device. For samples having a
humidity content up to 60%, weigh 2g of sample with an accuracy of
0.1mg, for
samples having a humidity content higher than 60% weigh 3g of sample with the
same accuracy.
2) Reagents for digestion:
for each sample add in the test tube:
2 catalyst tablets CM (code CT0006650)
15 ml concentrated sulphuric acid (96-98%)
shake gently the test tubes.
3) Digestion:
heat for 70 min at 420 °C.
4) Cooling:
let cool the test tubes to 50-60 °C.
5) Distillation-titration:
place in position the test tube with digested sample in the
unit UDK 139.
factor: 6.25
Addition of reagents:
dilution water=50ml
H
3
BO
3
=30ml
NaOH=60 ml
Titrant: HCl 0.2N
Distillation time= 4 min
Steam power= 100%
Press the button starting distillation cycle.
References:
AOAC, “Official methods of analysis”, method 984.13
268
