1.0) Description: Brown colour powder, free from any foreign matter.
2.0) Solubility : Soluble in water.
Tests:
3.1) pH: (Between 4.0 & 7.0)
Weigh 1gm of substance; add 49 gm of demineralized water. Stir well to form uniform dispersion.
Keep for 5 minutes. Check pH of the dispersion using calibrated pH meter.
3.2) Particle size: (Limit: NLT 99% w/w passes through 100# ASTM sieve)
Sieve test on wet slurry
Determine on 5gm of sample as 5% w/w dispersion in Dichloromethane (MDC) and Isopropyl alcohol
(IPA) using following procedure: –
- I) Add 33.25gm of Isopropyl alcohol in a 250ml beaker and put the beaker under stirrer.
- II) Start stirrer and continue stirring of IPA till it forms deep vortex.
III) Add 5gm sample slowly to the IPA while stirring. Stir this dispersion for 2 minutes.
- IV) To this dispersion add 61.75gm of Dichloromethane, stir till deep vortex is formed and then
continue stirring for 45 minutes.
- V) Weigh, clean and dry 100# sieve, record the weight of empty sieve.
- VI) Pass the sample dispersion through tarred 100-mesh sieve.
VII) Sieve it without applying any pressure. Whatever remains on mesh is allowed to pass through
sieve with the help of running tap water, after some times the condition comes, when no
single particle passes through the sieve, remove sieve and keep it in oven.
VIII) Dry the matter on the sieve by keeping sieve in oven at 1050C for 30 minutes.
- IX) Remove the sieve from oven, allow it to cool
- X) Weigh dried material on the sieve after it reaches to room temperature
Calculation: – Percentage w/w passed through 100 # Sieve=
= Weight of sample taken – Weight of remnant X 100
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Weight of sample taken
3.3) Bulk density: (Between 0.4 & 0.9 gm/cc)
Weigh 5gm substance and pour into a calibrated 50ml measuring cylinder. Gently level the substance in cylinder. Check volume occupied by substance.
Bulk Density = Weight of substance
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Volume occupied by substance
3.4) Ash: (NMT 35.00% w/w)
Weigh accurately 1 gm of the substance, in a suitable crucible that previously has been ignited, cooled
and weighed. Heat gently until the substance is thoroughly charred. Cool and then ignite at 800 ± 25°
for 30 minutes until the carbon is consumed. Cool in a desiccator, weigh and calculate the percentage of the residue by formula
% Ash = (Weight of crucible + residue) – Weight of empty crucible x 100
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Weight of sample
3.5) Arsenic: [Not more than 2 ppm]
This procedure is designed to determine the presence of trace amounts of arsenic (As) in a Instacoat
substance.Reagents:
Stannated hydrochloric acid (AsT): 1ml Stannous chloride solution AsT + 100ml Hydrochloric acid
1M Potassium iodide: Dilute 166gm of Potassium iodide to 1000ml with water.
Standard Preparation: Dilute 4ml of arsenic standard solution (1ppm As) to 15ml with water.
Test Preparation: Take 2gm of Instacoat substance in a crucible & ignite it at 600°C take residue in a
Arsenic test bottle Add 15 ml water.
Apparatus: The apparatus consists of a 100-ml bottle or conical flask closed with a rubber or ground
glass stopper through which passes a glass tube (about 20 cm X 5 mm). The lower part of the tube is
drawn to an internal diameter of 1.0 mm, and 15 mm from its tip is a lateral orifice 2 to 3 mm in
diameter.When the tube is in position in the stopper the lateral orifice should be at least 3 mm below the lower
surface of the stopper. The upper end of the tube has a perfectly flat surface at right angles to the axis
of the tube. A second glass tube of the same internal diameter and 30 mm long, with a similar flat
surface, is placed in contact with the first and is held in position by two spiral springs or clips. Into the
lower tube insert 50 to 60 mg of lead acetate cotton, loosely packed, or a small plug of cotton and a
rolled piece of lead acetate paper weighing 50 to 60 mg. Between the flat surfaces of the tubes place a
disc or a small square of mercuric chloride paper large enough to cover the orifice of the tube (15 mm X 15 mm).
Procedure: Take 15 ml of sample preparation and standard preparation into the Std & Spl AS-Test
Bottle, add 15 ml of stannated HCl AsT, 5 ml of 1M potassium iodide and 10 g of zinc AsT. Immediately assemble the apparatus and immerse the assembly in a water-bath at a room temperature such that a uniform evolution of gas is maintained.
Observation: After 40 minutes, any stain produced on the mercuric chloride paper is not more intense
than that obtained by standard solution.
Note: If required expose standard and test paper to Ammonia vapour, dry in air and compare the yellow stain.
3.6) Heavy Metals: [Not more than 10 ppm]
Lead Nitrate Stock Solution— Dissolve 159.8 mg of lead nitrate in 100 ml of water to which has been added 1 ml of nitric acid, then dilute with water to 1000 ml (100μg/ml). Prepare and store this solution in glass containers free from soluble lead salts.
Standard Lead Solution— On the day of use, dilute 10.0 ml of Lead Nitrate Stock Solution with water to 100.0 ml. Each ml of Standard Lead Solution contains the equivalent of 10 μg of lead.
pH 3.5 Acetate Buffer— Dissolve 25.0 g of ammonium acetate in 25 ml of water, and add 38.0 ml of 6 N hydrochloric acid. Adjust, if necessary, with 6N ammonium hydroxide or 6 N hydrochloric acid to a pH of 3.5 dilute with water to 100 ml, and mix.
Standard Preparation— Into a 50-ml color-comparison tube pipette 2 ml of Standard Lead Solution (10 μg of Pb), and dilute with water to 25 ml. Using a pH meter or short-range pH indicator paper as
external indicator, adjust with 1N acetic acid or 6N ammonium hydroxide to a pH between 3.0 and 4.0,
dilute with water to 40 ml, and mix.
Test Preparation— Weigh accurately quantity of the sample (calculated as per formula 2.0/1000L,
where L is the Heavy metal limit in percentage). Transfer the weighed quantity of the substance to a
suitable crucible, add sufficient sulfuric acid to wet the substance, and carefully ignite at a low
temperature until thoroughly charred. (The crucible may be loosely covered with a suitable lid during
the charring.)Add to the carbonized mass 2 ml of nitric acid and 5 drops of sulfuric acid heat cautiously until white
fumes no longer are evolved. Ignite, preferably in a muffle furnace at 500 to 600°C for 30 minutes.
Cool, add 4 ml of 6N hydrochloric acid, cover, digest on a steam bath for 15 minutes, uncover, and
slowly evaporate on a steam bath to dryness. Moisten the residue with 1 drop of hydrochloric acid, add
10 ml of hot water, and digest for 2 minutes.Add 6N ammonium hydroxide drop wise until the solution is just alkaline to litmus paper, dilute withwater to 25 ml, and adjust with 1N acetic acid to a pH between 3.0 and 4.0, using short-range pH
indicator paper as an external indicator. Filter through Whatman filter paper No. 42, rinse the crucible
and the filter with 10 ml of water, combine the filtrate and rinsing in a 50-ml color-comparison tube,
dilute with water to 40 ml, and mix.
Procedure— To each of the tubes containing the Standard Preparation and the Test Preparation, add 2
ml of pH 3.5 Acetate Buffer, then add 1.2 ml of thioacetamide–glycerin base TS, dilute with water to 50 ml, mix, allow to stand for 2 minutes, and view downward over a white surface the color of the solution from the Test Preparation is not darker than that of the solution from the Standard Preparation.
