Page 139 - Feed Lab

Suguna Management System Ver 1.0 / SOP / FQL / P3 - 04 Page 1 of 1

4. Determination of Chromium (DPC Method)

Add 5-6 drops of solution A and then add 2-3
PRINCIPLE
drops of solution B (freshly prepared).
Leather meal is waste by-products from hide ( Picture -2)
trimmings, which contain chromium salts. When a
sample is ashed, the visible dark green chromium FA red-violet color indicates the presence of
salts develops. Diphenyl carbazide is an excellent chromium. (Picture -3)
reagent to react with chromium in dilute sulphuric
acid (0.1 M H SO ) which produces a violet colour
4
2
and will fade within 10-15 minutes.

REAGENTS
FSolution A: 0.1M H SO 4
2

FSolution B: Dissolve 1-2 g diphenyl carbazide
in 100 ml of acetone (freshly prepared).
Picture - 1 Picture - 2
PROCEDURE
0
FAsh fish meal / MBM test sample at 600 C for
90 minutes (before that Ignite the sample on a
burner till smoke cease off) and examine for the
presence of dark green chromium salts. Dark
green particle of ash is a conductive evidence
of the adulteration of leather meal in the
sample. (Picture -1)

Picture - 3
FTo confirm the presence of chromium, place a
small amount of ash into a white spot plate.

Prepared by : Approved by :
125 Director - Technical