standard testing procedure Calcium carbonate oyster shell powder

Storage Requirements:
Store protected from light and moisture.

Sampling:
Sample from each container / bag and collect a minimum of 5g from each of the randomely selected containers/bags into indiviually no toxic,

selfsealing transparent polyethylene bearing ‘Sample For Analysis’ label kept in another transperent self sealing polythene bag.

Afetr completion of sampling return rest sample on the same container. Collect control sample in Pet bottle/Glass bottle.

Quantity of Composite Sample:

15 g

Quantity of Control Samle:

2 X 15 g

Description: White, crystalline or microcrystalline powder.

Solubility: Practically insoluble in water and in ethanol (95%), slightly soluble in water containing

carbon dioxide or ammonium salt; It is soluble with effervescence in dilute acids.

Identification:
A. By Chemical: 0.2 ml of the filtrate (Solution A) gives reactions A and B of calcium salts
B. By Chemical: Gives reaction A of carbonates.

Substances insoluble in acetic acid: The residue weighs NMT 10mg (0.2 per cent).

Arsenic: The resulting solution complies with the limit test for arsenic (4ppm).

Heavy Metals: NMT 20ppm

Barium: The solution remains clear for not less than 15 minutes.

Iron: NMT 200ppm

Magnesium & alkali metals: The residue weighs not more than 5 mg (1.0 per cent).

Chlorides: NMT 250ppm

Sulphates: NMT 0.3 %

Loss on Drying: NMT 2.0%w/w

Assay: 98.0% to 100.5%w/w on the dried basis.

Description: White, crystalline or microcrystalline powder.

Reporting: Report as Complies/Does not comply.

Solubility: Use the following quantities:
It is soluble with effervescence in dilute acids : 1 g in 10 to 30ml.
Slightly insoluble in water containing carbon dioxide or ammonium salt : 0.1 g in 10 to 100ml .
Practically insoluble in water and ethanol (95%) : 0.01 g in 100ml or more.
Reporting: Report as Complies/Does not comply.

Identification:

(A) Dissolve 5.0g in 80 ml of 2M acetic acid when effervescence ceases, boil the solution for 1 minute,
allow to cool, dilute to 100 ml with 2M acetic acid and filter 0.2 ml of the filtrate (Solution A) gives
reactions a and b of calcium salts.
(a) To 0.2 ml of the add filtrate add 0.5 ml potassium ferrocynide solution, the solution remains
clear. Add about 50 mg of ammonium chloride, a white crystalline precipitate is formed.
(b) To 0.2 ml of the filtrate, add 0.2 ml of a 2% w/v solution of ammonium oxalate. A white
precipitate is obtained that is only sparingly soluble in dilute acetic acid but is soluble in HCl

Reporting: Report as Complies/Does not comply.

(B) Gives reaction A of Carbonates:
Suspend 0.1g of the substance in a test tube in 2ml water. Add 2ml of 2M acetic acid. Close the tube
Immediately using a stopper fitted with a glass tube bent at two right angles Heat gently and collect
the gas in 5ml of 0.1 M barium hydroxide. A white precipitate us formed
Reporting: Report as Complies/Does not comply.

Substances insoluble in acetic acid:
Wash any residue obtained in Identification test A with four quantities, each of 5 ml of hot water and dry at 100° for 1 hour;

the residue weighs not more than 10 mg (0.2 per cent).

Where: W1 = Weight of sample, W2 = Weight of sintered glass & W3 = Weight of sintered glass with residue.

Reporting: Report as Value.

Arsenic:
Dissolve 2.5g in15 ml brominated hydrochloric acid and 45ml of water and remove the excess of
bromine with a few drops of stannous chloride solution AST. The resulting solution complies with
the limit test for arsenic.

Reporting: Report as Complies/Does not comply.

Heavy Metals:
To 1g add 5 ml water, add 8 ml of dilute hydrochloric acid, the latter being added slowly, shake and
evaporate to dryness on a water-bath. Dissolve the residue in 20ml of water, filter, add to the filtrate
3 ml of dilute acetic acid and water to make 25ml. This solution complies for the limit test.

Reporting: Report as Complies/Does not comply.

Barium:
Dissolve 0.6 g in 10 ml of 2M acetic acid by boiling cool and add 10 ml of calcium sulphate solution,
the solution remains clear for not less than 15 minutes.

Reporting: Report as Complies/Does not comply.

Iron:
Dissolve 0.2 g in 5 ml water and 0.5 ml of iron-free hydrochloric acid. Boil and dilute to 40ml with water
the solution complies with the limit test for iron.

Magnesium & alkali metals:
Dissolve 1.0g in10 ml of dilute hydrochloric acid, neutralise the solution by adding dilute ammonia
solution. Heat the solution to boiling and add 50ml of hot ammonium oxalate solution. Cool, dilute to
100 ml with water & filter.
To 50ml of the filtrate, add 1.5 ml of dilute sulphuric acid evaporate to dryness on a water-bath, heat the residue
to redness, allow to cool and weigh. The residue weighs not more than 10 mg.

Reporting: Report as Value.

Chloride:
1g dissolved in water by the addition of 3 ml of nitric acid complies with the limit test for chlorides.

Reporting: Report as Complies/Does not comply.

Sulphates:
Suspend 50.0mg in 5ml of water and add drop wise sufficient dilute hydrochloric acid to effect solution. Add 2ml of
dilute hydrochloric acid; the resulting solution complies with the limit test for sulphates.

Reporting: Report as Value.

Loss on Drying:
Determined on 1.0 g by drying in an oven at 200°C till constant weight.

Reporting: Report in %.

Assay:
Weigh accurately about 0.1g and dissolve in 3ml of dilute hydrochloric acid and 10ml of water. Boil for
10 minutes, cool and dilute to 50ml with water. Titrate with 0.05M disodium edetate to within a few ml of the expected end-point, add 8 ml of

sodium hydroxide solution and 0.1g of calcon mixture and continue the titration until the colour of the solution changes from pink to a full blue colour.

1 ml of 0.05M disodium edetate is equivalent to 0.005004g of CaCO3.