ANKOM TDF Dietary - Manual (Page 60)

Operator’s Manual
pg. 60
Rev E 12/2/14
SDF / TDF – Kjeldahl Method
To determine the protein content within the SDF or TDF residue, follow the procedure below.
1. Cut the filter bag 8 -10 mm above the filter.
2. Fold the remainder of the filter bag in thirds from side to side.
3. With your Heat Sealer set to “6” (setting may vary depending on heat sealer and power source), press the arm
down for 3 to 4 seconds to seal the polypropylene edge of the filter bag. Repeat if necessary.
4. Label the folded, sealed filter.
5. Repeat steps 1 – 4 for all SDF bags that will be used for determining protein content.
6. Run a Kjeldahl procedure on each filter bag using 27 ml of H
2
SO
4
, 13 g of K
2
SO
4
, and 45 mg of CuSO
4

5H
2
O in a
system with 250 ml tubes that have a 42 mm diameter. Pellets can be used if an equivalent amount of K
2
SO
4
is
added. To slow down the rate of foaming during the digestion process, ramp up the temperature slowly.