These test methods of determination of chloride content. or determination of chloride.
Reagents
a. Dilute Nitric Acid, 10% w/w or approximately 1N.
b. Calcium Nitrate solution, 20% w/v aqueous solution
c. Silver Nitrate solution, 0.1(N) standardized.
d. Methyl Orange indicator, 0.1% w/v solution in 95%
Rectified Spirit.
e. Potassium Chromate solution, 5% w/v aqueous solution
Procedure of Chloride Content as NaCl
Dissolve about 10 gm of the sample (W), accurately weighed
in about 100 ml of hot water in a tall 250 ml beaker, add 20 ml of Calcium
Nitrate solution, mix, cool, and filter through a Whatman No 1 filter paper, collecting
the filtrate in a 250 ml volumetric flask. Wash the filter free from chlorides
using Water, dilute the filtrate, and wash to 250 ml with water, cooling to 20
deg C, if necessary, and mix.
Pipette 100 ml of the prepared solution into a conical
flask, neutralize with the dilute Nitric acid to Methyl Orange pink, and
titrate with 0.1(N) Silver Nitrate solution, using Potassium Chromate as an indicator (V1 ml). Carry out a blank determination using the same quantity of
all reagents except the sample. Note the volume (V2)
Calculation of Chloride Content as NaCl
= 14.6 x (V1-V2) x N/W
Chloride content, %w/w (calculated as NaCl) =
Where,
V1 = Volume in ml of 0.1(N) Silver Nitrate solution required
for the material.
V2 = Volume in ml of 0.1(N) Silver Nitrate solution required
for the blank.
W = Weight of the sample taken in gm.
N = Actual normality of 0.1N Silver Nitrate solution 4 is
the correction factor
Lather value test in Soap
It consists of a three-speed kitchen blender with a glass
container of 1000 ml capacity, one 1000 ml and one 500 ml capacity graduated
measuring cylinder of IS std 878:1975. ( The liquidizer blade type that is
usually fixed to a Philips mixie is suitable.)
Preparation of sample :
Particle Size Reduction of Sample: The bathing bar sample
shall be grated through a 1.70 mm sieve (see Note ). It may be necessary to
clean the sieve more often during grating in the case of a bathing bar that is
soft and sticky. If the bar is too dry and gets powdery during the grating
operation, second sieving of the gratings through a 500-micron sieve is needed
and particles are passing through this sieve shall be rejected. The sieved
gratings shall be stored in airtight containers before use in lather
measurements.
[ NOTE: Reduction of particle size of bathing bars needs a
certain extent of skill. A set of sieves as
mentioned in the method can be used in conjunction with a
food grater. Food graters with openings of various sizes & shales are
available and the suitable type should be chosen to grate bathing bars having
different stickiness, moisture and other characteristics. The amount of manual
pressure applied by an operator during the grating operation also decides the
average particle size and particle size distribution. With some experience, the
operator should be able to get particles suitable for use in lather
measurement. ]
Preparation of standard solution :
Prepare a 1 % W/V solution of Sodium Lauryl Sulphate (ref
std IS 3986:1981)in 300 ppm water ( Ca: Mg - 3:2 as per IS 3785:1976).
Procedure :
1. Measurement of Lather Volume
100 ml of the solution of Sodium Lauryl Sulphate shall be
poured into the blender jar of a mixie fixed with a 450W motor covered and
blended on low speed for exactly 60 seconds. The blender shall be operated at an
input voltage of 230+ / - 10 V at the low setting( popular kitchen mixies have a nearly identical speed of rotation). The blender jar is then held inverted over
the 1000 ml or 500 ml capacity measuring cylinder and any lather adhering to
the jar shall be scooped out and allowed to drain. The lather volume shall be measured
after levelling off the top surface of the foam.
All experiments are to be carried out at 27 +/- 2 deg C .
All apparatus and chemicals involved should also be
maintained at the above temperature. The lather volume obtained with 1 %
solution of sodium lauryl sulphate should be 600 +/- 100 ml. [NOTE: 1. If the lather volume generated is less than 500 ml, use a 500 ml cylinder, higher lather
volume needs a 1000 ml capacity cylinder.
2. Measurement of the temperature of water drained out of the foam
is essential despite maintaining a constant temperature
environment. Depending upon the atmospheric temperature prevailing in the
laboratory at the time of measurement and the nature of the mixie. the starting
temperature of the water has to be a few
Test Method
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lower or higher than the temperature at which measurement is needed.]
2. Measurement of Lather Volume of Sample
Take 100 ml of 300 ppm hard water ( Ca: Mg - 3:2 as per IS
3785:1976) in the blender jar and add 5 gm of grated bathing bar sample to the
water in the blender jar, cover and blend at low speed for exactly 60 seconds.
Pour the lather quickly into the cylinder IS std 878:1975 and measure the
lather volume immediately after levelling the top surface of the foam. Only
the top height should be read.
Repeat 1 and 2 for the next two samples. Take three
determinations for each sample and report the average value (see note ) The
value for sodium lauryl sulphate determined during each measurement should be
used to normalise the value of the bathing bar based on the standard at 600
ml.
[NOTE: 1. If the lather volume generated is less than 500 ml,
use a 500 ml cylinder, higher lather volume needs a 1000 ml capacity cylinder.
2. Measurement of the temperature of water drained out of the
foam is essential despite maintaining a constant temperature
environment. Depending upon the atmospheric temperature prevailing in the
laboratory at the time of measurement and the nature of the mixie. the starting
temperature of the water has to be a few degrees lower or higher than the
temperature at which the measurement is needed.]