Page 84 - Feed Lab

Estimation of Chloride as Sodium Chloride Suguna Management System Ver 1.0 / SOP / FQL / P2 - 1 1 Page 2 of 2

Standardization of silver nitrate
FThe 0.1N silver nitrate is standardization with 0.1N
sodium chloride using potassium chromate as
indicator. The end point is the appearance of
reddish tinge on the precipitate (Mohr's method).

PROCEDURE
FWeigh 10g for feed and 5 gram for dry fish /
Picture-7 Picture-8
fishmeal or high salt sample in a 250 ml beaker.
(Picture-9)
REAGENTS
F0.1N Silver nitrate: Dissolve approximate 1.699g FAdd 100 ml of distilled water, stir with glass rod for 5
of silver nitrate, AR grade in distilled water and to 10 minutes and filter. (Picture-10)
made up to 100 ml
FFrom this filtrate, withdraw aliquot of 10 ml and add
F0.1N Potassium thio cyanide: Dissolve 5 ml (for feed), 15 ml (for fish meal/ high salt sample)
approximately 0.978g of potassium thiocyanide, of 0.1 N silver nitrate + 5 ml of nitric acid + 3 ml of
AR grade in distilled water and made up to 100 ml. 5% ferric alum. (Picture-11)
F0.1N Sodium chloride: Dissolve approximately FBoil gently until all solids except silver chloride is
0.585g of sodium chloride, AR grade in distilled dissolved and cool. Titrate, 0.1N Potassium thio
water and made up to 100 ml cyanide until solution becomes reddish tinge
colour. (Picture-12)
F2% Potassium chromate w/v, AR grade
F Do the blank titration, taking 10 ml water + 10 ml 0.1
F5% ferric alum (16g of Ammonium ferric sulphate in N silver nitrate + 5 ml nitric acid + 3 ml 5% ferric
300ml of distilled water) alum. Boil and cool. Then titrate with 0.1N
potassium thio cyanide. From the titrate value we
F1:1 Nitric acid
can calculate the normality of potassium thio
cyanide.

Picture-9 Picture-10 Picture-11 Picture-12

58.45 X {(vol. of silver nitrate X N. of silver nitrate) -
CALCULATION
(Vol. of KSCN X N. of KSCN)} X 100 x 100
Percentage of chloride as sodium chloride = -------------------------------------------------------------
Sample weight, g x 10 x 1000
Note: If the end point (red colour) appears within 2-3
drops of 0.1N Potassium thiocyanide, reconfirm the REFERENCE:
result by adding more quantity of 0.1 N silver nitrate. 1. Bureau of Indian Standard IS 7874 1975
2. Association of Official Analytical Chemist 2000.

Prepared by : Approved by :
72 Director - Technical