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Ref. No, : ISO/R 894-1968 (E)
IS0
INTERN AT I ON A L ORGAN I Z AT 1 ON FOR STA N DARD IZATl O N
IS0 RECO M M EN DATI ON
R 894
SURFACE ACTIVE AGENTS
TECHNICAL SODIUM PRIMARY ALKYLSULPHATES
METHODS OF ANALYSIS
1st EDITION
December 1968
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 894, Surfàce active agents ~ Technical sodium primary alkylsulphates - Methods
of'analysis, was drawn up by Technical Committee ISO/TC 91, Surface active agents, the Secretariat of which is held
by the Association Franqaise de Normalisation (AFNOR).
Detailed work on this question by the Technical Committee led, in 1963, to the adoption of a Draft IS0
Recommendation.
In March 1967, this Draft IS0 Recommendation (No. 1035) was circulated to all the IS0 Member Bodies for
c
enquiry. It was approved, subject to a few modifications of an editorial nature, by the following Member Bodies :
Australia Hungary Romania
Austria Iran South Africa, Rep. of
Belgium Ireland Spain
Israel Switzerland
Brazil
ltaly Turkey
Canada
Czechoslovakia Japan U.A.R.
France Netherlands United Kingdom
Germany New Zealand Yugoslavia
Greece Portugal
No Member Body opposed the approval of the Draft.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council, which decided.
in December 1968, to accept it as an IS0 RECOMMENDATION.
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lSO/R 894-I968(E)
CONTENTS
Page
............................... 5
Introduction
........................... 6
Part 1 General
......................... 6
1. Scope
2. Field of application . 6
3. Preparation of sample . . 6
4. General principle . 7
l’art 11 Determination of water content . 8
1. Karl Fischer method. .
8
3. Azeotropic method .
9
Part I11 Measurement of pH . 11
Part IV Determination of free alkalinity or free acidity .
13
Part V ~ Determination of total alkalinity . 13
Part VI Determination of matter extractable by hexane . 14
Part VI1 Determination of matter extractable by diethyl ether after acid hydrolysis
(combined technical fatty alcohols) .
17
- Determination of the combined sulphur content arising from the sodium alkylsulphate
Part VI11
20
l’art IX . Determination of sodium sulphate content . 21
Part X ~ Determination of sodium chloride content . 23
Part XI - Report of the analysis . 24
Appendix Y ~ General scheme of analysis . 25
Appendix Z ~ Determination of water content (Karl Fischer method using two solutions) . 26
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ISO/R 894-1968(E)
IS0 Recommendation R 894 D ece m be r 1 968
SURFACE ACTIVE AGENTS
TECHNICAL SODIUM PRIMARY ALKY LSULPHATES
METHODS OF ANALYSIS
INTRODUCTION
The word “primary”, preceding the generic name for the products in the title, is intended to distinguish products
from those which, in accordance with current scientific usage, could be designated as technical sodium secondary
alkylsulphates. As shown in the general formula given below, the former are derived from primary alcohols, whereas
the latter may be considered as derived from secondary alcohols.
It is therefore the former which are the subject of this IS0 Recommendation. They are commonly known today as
technical sulphates of primary fatty alcohols.
In order to simplify the text of this IS0 Recommendation and avoid unecessary repetition, the word “primary” has
been omitted from the term “sodium aikylsulphates”, but it should be understood that only “sodium primary
alkylsulphates” are covered.
The general formula of the products which are the subject of this IS0 Recommendation is
R-CH2 -O-S03Na
where R is an aliphatic radical.
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ISO/R 894-1968(E)
PART I
GENERAL
1. SCOPE
This IS0 Recommendation describes the methods of analysis of technical sodium primary aikylsulphates. It
covers the following determinations :
Determination of water content.
Measurement of pH.
Determination of free alkalinity or free acidity.
Determination of total alkalinity.
Determination of matter extractable by hexane.
Determination of matter extractable by diethyl ether after acid hydrolysis (combined technical fatty alcohols).
Determination of the combined sulphur content arising from sodium alkylsulfate.
Determination of sodium sulphate content.
Determination of sodium chloride content.
It also describes in Appendices.
a general scheme of analysis;
( 1 )
a method for the determination of water, using the Karl Fischer technique with two solutions.
(2)
2. FIELD OF APPLICATION
This IS0 Recommendation applies only to technical sodium alkylsulphates in powder, paste or liquid form
(aqueous solution), free from any product extraneous to their manufacture.
3. PREPARATION OF SAMPLE
3.1 Procedure
In all cases, and as a first step, prepare a representative sample. The procedure depends on the physical nature
of the product.
3.1.1 Products in powder form. If a suitable conical divider is available, proceed in accordance with IS0 Recom-
mendation R 607, Surface active agents in powder form - Preparation of a reduced sample, until a reduced
sample of approximately 300 g is obtained.
If such a divider is not available, spread a representative mass of 1000 g of the product in powder form on a
sheet of white filter paper. Crush any large grains by means of a spatula. Then, using the method of alternate
quarters, prepare a representative sample of approximately 300 g.
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ISO/R 894-1968(E)
3.1.2 Products in paste form. First of all determine the pH value of the paste by means of contact electrodes or
a suitable indicator paper. If the pH is not below 7, the following procedure may be adopted : Stir the paste
with a stout glass rod, at the same time exposing it to a moderate heat of 40 to 50 "C (water bath or hot-
plate) until a homogeneous mass is obtained. While still stirring it, let it cool to a temperature between
15 and 30 OC, obtaining, in this way a very thick paste, which may be regarded as a representative sample.
The mass (including the glass rod) should be determined both before and after the operation in order to
determine any losses due to evaporation of water, which should be taken into consideration.
If, on the other hand, the pH value of the paste is below 7, add for each 50 g of paste 5 drops of 0.2
alcoholic solution of phenolphthalein, stir with a strong nickel spatula, then still stirring, add 0.5 N alce
holic potassium hydroxide drop by drop until a pink colour is obtained. Then proceed as specified above,
including the determination of mass before and after the operation (see Part III, section 2 and Part IV,
section 3 of this IS0 Recommendation).
3.1.3 Liquid products. If the liquid is homogeneous and clear, it may be regarded as a representative sample. If
the liquid is turbid, or if it contains a deposit, it should be stirred before the representative sample is taken.
If it contains a compact or crystalline deposit, it should be carefully heated to a temperature of about 30 "C
until the deposit can be uniformly distributed by stirring, or until the crystals disappear.
3.2 Storage
Liquid products or those in paste form should be kept in wide-necked flasks with ground-glass stoppers and not
in metallic containers.
4. GENERAL PRINCIPLE*
Preparation of an aqueous alcoholic solution of a test portion of the raw material, from which are isolated the
products extractable by hexane.
Evaporation to dryness of the residual aqueous alcoholic liquor in the presence of propan-2-01. Hot acid hydrolysis
of the dry residue and isolation from the acid reaction liquor of all products extractable by diethyl ether (combined
technical fatty alcohols).
On the residual acid aqueous liquid, determination of the total sulphate. The difference between the percentage of
total sulphate and inorganic sulphate determined separately, makes it possible to calculate the content of combined
sulphur arising from the sodium alkylsulphate.
On separate test portions of the representative sample of the raw material,
- determination of water content,
- measurement of pH,
~
determination of free alkalinity or free acidity,
- determination of total alkalinity,
-
determination of sodium sulphate content,
determination of sodium chloride content.
*
See the general scheme of the method in Appendix Y.
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ISO/R 894- 1 %8( E)
PART II
DETERMINATION OF WATER CONTENT
Depending on the amount of water in the product, carry out the determination according to one of the two
following methods :
The Karl Fischer method, applicable to products having up to 10 of water;
(a)
of water.
the azeotropic method, which should be used only for products containing more than 5
(b)
1. KARL FISCHER METHOD
1.1 Introduction
The Karl Fischer reagent is a solution containing anhydrous pyridinium sulphite and iodine, which are
transformed in the presence of the slightest trace of water into pyridinium sulphate and hydriodic acid
respectively.
It is possible to proceed in one of two ways, as follows :
by determining the water in the product directly with the Karl Fischer reagent as a single solution, but
(a)
since this liquid has reduced stability unless it has been specially stabilized, this technique is recom-
mended only when the determination has to be carried out frequently enough for the single reagent to
be used up each day or when the stabilized reagent is available;
by determining the water by means of the iodine solution after adding anhydrous pyridinium sulphite
(b)
solution to the product. These two liquids can be kept much longer apart than when mixed and this
technique, although also applicable in the other case, is particularly recommended when determinations
have to be carried out at more or less regular intervals.
1.2- Method using a single solution
*./Y.
In a solution or suspension in methanol of a test portion of the representative sample of the raw material
such that the water it contains requires a measurable quantity of Karl Fischer reagent, determine the water
in accordance with IS0 Recommendation R 760, Determination of water in chemical products by the
Karl Fischer method.
Reproducibility
The difference between the results obtained on the same sample, in different laboratories, should not exceed
0.2 g of water for 100 g of sample.
1.3 Method using two solutions
See Appendix Z
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ISO/R 894-1968(E)
2. AZEOTROPIC METHOD
2. I Principle
Entrainment of the water in the vapour state, by ,oiling xylene.
2.2 Reagent
Xylene, commercial quality (any isomer or mixture of isomers in any proportion) saturated with water.
2.3 Apparatus
2.3.1 Apparatus comprising the following :
a short-necked round-bottomedflask not less than 500 ml, connected to the tube, shown below, by
(a)
means of a ground-giass joint;
a graduated cylindrical tube, shown diagramatically below, with or without discharge tap;
(b)
a straight reflux condenser, connected to the tube by means of a ground-glass joint
(c)
2.3.2 Analytical balance.
Discharge
NOTE. - Before use, clean the graduated tube and the interior of the reflux condenser of all trace of fatty matter, for
example, by washing them successively in chromic/sulphuric acid mixture, then with distilled water, and finally with acetone.
Dry them. Perfect cleanliness of the apparatus is essential for the success of the test.
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ISO/R 894-1968(E)
Procedure
2.4
2.4.1 Test portion. Weigh, to the nearest 0.01 g, 10 to 50 g of the representative sample of the raw material into
the flask according to whether it is a liquid, a paste or a powder.
2.4.2 Determination. Add to the test portion 100 to 300 ml of xylene and a dry boiling aid, for example a few
fragments of pumice stone.
Attach the flask to the rest of the apparatus.
Heat gradually to boiling (2 to 3 drops per second) and maintain at this temperature until the distilled
xylene becomes clear and water no longer separates from it.
if drops of water adhere to the sides of the tube, remove them by warming the tube carefully, using a small
flame.
if foaming is troublesome during the determination, it can be eliminated by adding, for example, dry paraffin
wax or dry oleic acid to the flask.
Leave to settle until the water has completely separated without an emulsified layer.
Read the volume of the water in the graduated tube, at the standard reference temperature of 20 OC.
2.5 Expression of results
2.5.1 Method ofcalculation and formula. The percentage of water in the sample is equal to
1 O0
VX-
M
where
M is the mass, in grammes, of the test portion;
V is the volume, in millilitres, of the aqueous layer.
2.5.2 Reproducibility. The difference between results obtained on the same sample, in two different labora-
tories, should not exceed 1 g of water for 100 g of sample.
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ISO/R 894-1968(E)
PART III
MEASUREMENT OF pH
1. PROCEDURE
Using distilled or de-ionized water of pH between 6.5 and 7, prepare a solution 5 (m/m) of the representative
sample of the raw material (see section 2 below). Measure the pH to the nearest 0.1 unit, by means of a pH meter
suitable for this purpose.
Read the meter as rapidly as possible, i.e. between 30 seconds and 1 minute after immersion of the electrodes.
2. NOTE
In the case of products in paste form, a distinction has to be made between two cases,i.e. during preparation of
the sample (see Part I, clause 3.1.2 of this IS0 Recommendation), the raw material in paste form, to be analysed,
has shown on preliminary examination either
a pH not below 7, in which case, it is possible to apply the procedure described in section 1, to a test portion
(a)
of the representative sample of the raw material, prepared in accordance with Part I, clause 3.1.2 of this IS0
Recommendation, or
a pH below 7, in which case it is necessary to apply the procedure described in section 1 to a test portion of
(b)
the raw material as it is, whatever its state of homogeneity.
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E
ISO/R 894-1968(E)
PART IV
DETERMINATION OF FREE ALKALINITY OR FREE ACIDITY
1. DEFINITION
By “free alkalinity” or “free acidity” is understood alkalinity or acidity determined using phenolphthalein as
indicator under specified conditions. It is expressed as the alkali value or the acid value as the case may be.
2. PROCEDURE
Dilute or, where applicable, dissolve 10 g of the representative sample of the raw material (see section 3 below) in
100 ml of propan-2-01, 50 O/,, (v/v), previously neutralized in the presence of phenolphthalein, and determine either
the acidity or the alkalinity, by titration with a suitable 0.1 N standard volumetric solution (0.1 N potassium
hydroxide or O. 1 N hydrochloric or sulphuric acid).
3. NOTE
In the case of products in paste form, a distinction has to be made between two cases, i.e. during preparation of
the sample (see Part I, clause 3.1.2 of this IS0 Recommendation) the raw material in past form, to be analysed,
has shown on preliminary examination
a pH nor below 7, in which case it is possible to apply the procedure described in section 2 to a test portion
(a)
of the representative sample of the raw material, prepared in accordance with Part I, clause 3.1.2 of this IS0
Recommendation;
a pH below 7, in which case it is necessary to apply the procedure described in section 2, to a test portion of
(b)
the raw material as it is, whatever its state of homogeneity.
4. EXPRESSION OF RESULTS
Express the results as the acid value or alkali value, whichever is appropriate, i.e. in milligrammes of potassium
hydroxide required to neutralize 1 g of the representative sample of the raw material.
The acid value (or alkali value) is equal to
5.61
VX-
M
where
M is the mass, in grammes, of the test portion;
is the volume, in millilitres, of the standard volumetric solution used.
V
NOTES
1. If the standard volumetric solution used is not exactly of strength 0.1 N, a suitable correction factor should be used in calculating
the results.
2. When the value found is less than 0.3, express the result as follows :
Acid value or alkali value (as appropriate) < 0.3.
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ISO/R 894-1968(E)
PART V
DETERMINATION OF TOTAL ALKALINITY
1. INTRODUCTION
It may happen that on measuring the pH value, in accordance with Part III of this IS0 Recommendation, a pH
which is significantly greater that 7 is observed, and that on determining the alkalinity, in accordance with Part IV,
an alkali value significantly greater than 0.3 is obtained. In such a case, it is advisable to carry out the determination
of the total alkalinity as below.
2. DEFINITION
By “total alkalinity” is understood the alkalinity determined using methyl orange (or bromophenol blue) as
indicator under specified conditions. It is expressed as alkali value.
3. PROCEDURE
Weigh, to the nearest 0.001 g, about 5 g of the representative sample of the raw material into a 100 ml beaker.
Transfer the product quantitatively with 100 ml of distilled water into a 250 ml conical flask, heating if necessary.
Add 5 drops of methyl orange (or bromophenol blue) and titrate at room temperature with a solution of 0.1 N
sulphuric acid until a colour change to a brownish red (or to yellow depending on the indicator used) is observed.
4. EXPRESSION OF RESULTS
Express the results as the alkali value as defined in Part IV of this IS0 Recommendation.
The total alkalinity, expressed as the alkali value, is equal to
5.61
VX-
M
where
M is the mass, in grammes, of the test portion;
V is the volume, in millilitres, of the standard volumetric solution used.
NOTE. - If the standard volumetric solution used is not exactly of strength O. 1 N specified above, a suitable correction factor
should be used in calculating the results.
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ISO/R 894-1968(E)
PART VI
DETERMINATION OF MATTER EXTRACTABLE BY HEXANE
1. INTRODUCTION
Matter extractable by hexane consists of sulphur-free products as well as products containing sulphur, which, when
present, are non-ionizable in aqueous solution.
2. PRINCIPLE
Extraction, by means of hexane, of the products specified in section I, in the aqueous alcoholic solution of the test
portion, taking into consideration the volatility of the products in question.
3. REAGENTS
3.1 Ethanol. 50 "1, (v/v) solution in distilled water.
3.2 Ethanol. 96 (v/v) solution.
' 3.3 Hrxane. not less than 95 (v/v).*
3.4 Sodium hydroxide, approximately 0.1 N solution in distilled water.
3.5 Sodium sulphate, neutral and anhydrous, analytical reagent grade.
4. APPARATUS
Ordinary laboratory apparatus not otherwise specified, and the following items:
round-bottomed distillation jlask, 250 ml, with ground-glass neck;
fa)
20 cm long and inside diameter approximately 8 mm, with a ground-glass cone at its
fractionating column
(b)
lower end to fit into the neck of the distillation flask;
three separating funnels, 500 ml, with ground-glass stoppers;
(c)
80 cm long;
vertical condenser,
(d)
beakers, 100 and 400 ml;
(e)
v> conicaljlask, 300 ml;
(g) hotplate or water bath;
(h) analytical balance.
*
If hexane is not available, use freshly distilled light petroleum spirit, of boiling range 30 to 60 OC. In reporting the results, it should
be stated which of the two solvents has been used.
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ISO/ R 894 - 1968(E)
5. PROCEDURE
5.1 Test portion
Weigh, to the nearest 0.01 g, a quantity of the representative sample of the raw material, such that it contains
approximately 4 g of sodium primary aikylsulphate, into the 100 ml beaker.
Let Mo be the mass weighed
5.2 Determination
Dissolve or, if necessary, dilute the test portion in 50 ml of very hot distilled water (approximately 70 OC)
stixing with a glass rod, then add 50 ml of ethanol (3.2) while continuing to stir. Introduce the liquid obtained
into one of the 500 ml separating funnels (A). Wash the beaker alternately with small equal portions of very
hot distilled water and of ethanol (3.2) until the final volume is approximately 300 ml.
Check that the liquid is slightly alkaline to phenolphthalein, and if necessary render it alkaline by means of the
sodium hydroxide solution (3.4) until a pale pink colour is obtained with the indicator (3.6).
Shake to render the mixture homogeneous. Allow to cool
Add 50 ml of hexane (3.3).
Shake vigorously for approximately 30 seconds and allow to separate. Add the minimum quantity of ethanol
(3.2) necessary to break any emulsion that may be formed.
Transfer the lower layer into a second separating funnel (B).
Extract with another 25 ml portion of hexane (3.3).
Collect the lower layer in a third separating funnel (C) and transfer the upper layer into the first separating
funnel (A).
Extract the aqueous alcoholic phase three more times, each time using 25 ml of hexane (3.3).
Combine the hydrocarbon phases in the separating funnel (A) and transfer the aqueous alcoholic phase into
the 400 ml beaker after the last extraction.
Wash the separating funnels (B) and (C) three times, each time using 10 ml of ethanol (3.1).
Add the washings to the aqueous alcoholic phase in the beaker.
Wash the hydrocarbon extract with portions of ethanol (3.1) until the washings are no longer aikaline; add
the washings to the aqueous alcoholic phase.
This solution LI is used for the determination of the content of combined technical fatty alcohols and of the
content of combined sulphur originating from the sodium alkylsulphate.
Transfer the hydrocarbon layer quantitatively into a 300 ml conical flask containing anhydrous neutral sodium
sulphate (3.5), Shake the liquid and allow it to stand for 30 minutes, then filter through filter paper into the
distillation flask, previously tared. Wash the conical flask, the sodium sulphate and the filter five times, each
time using 10 ml of hexane (3.3). Pay particular attention to the edges of the filter paper, which should not
show any greasy marks.
Fit the fractionating column to the distillation flask, place the assembly on the hotplate or in the water bath
and disti! until almost all the solvent has passed over. Remove the fractionating column, cool to about 30 “C
and eliminate the last traces of solvent by a gentle current of air.
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ISO/R 894 - 1968( E)
To do this maintain the current of air and rotate the flask by hand in an inclined position above the hotplate
or water bath. In this way, the liquid in the flask will spread over the interior in a thin film and so assist in
the removal of the last traces of solvent.
It is advisable to bear in mind that lower alcohols, such as lauric alcohol for example, are fairly volatile,
particularly in the presence of traces of moisture, which, in some circumstances, may cause quite considerable
losses. Therefore, particular care is necessary in evaporating the solvent, especially while passing the current
of air.
For this purpose, first weigh the flask, cooled to room temperature and carefully dried, while there is still a
detectable odour of solvent. Note the mass, then reheat the flask to approximately 30 "C so as to liquefy the
contents and pass a current of air over them for a further minute. After cooling and drying the flask, weigh it
again and note the mass.
By repeating these operations and plotting successive weighings on a graph on millimetre squared paper, it will
be noted that, after a rapid drop, the curve reaches a practically horizontal lower level. The second weighing
on the horizontal part is regarded as the end of the operation and the mass noted is recorded as that of the
final dry residue.
Any difference between the last two weighings should be apparent only in the third significant figure.
6. EXPRESSION OF RESULTS
6.1 Method of calculation and formula
The percentage of matter extractable by hexane in the representative sample of the raw material is equal to
1 O0
M, x-
Mo
where
is the mass, in grammes, of the test portion;
Mo
is the mass, in grammes. of the residue obtained.
Ml
6.2 Reproducibility
The difference between results obtained on the same sample, in two different laboratories, should not exceed
1 g of matter extractable by hexane for 100 g of sample.
I
16
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m
ISO/R 894-1968(E)
PART VI1
DETERMINATION OF MATTER EXTRACTABLE BY DIETHYL ETHER
AFTER ACID HYDROLYSIS (combined technical fatty aicohols)
1. PRINCIPLE
Evaporation, to a fifth of its volume, of the aqueous alcoholic liquid resulting from the previous determination, then,
after the addition of propan-2-01, evaporation to dryness. It is very important that the solution remain alkaline
throughout the whole of this determination.
Dissolution of the dry residue in distilled water, then, after the addition of hydrochloric acid, acid hydrolysis, at
boiling point. When the hydrolysis is complete, cold extraction by diethyl ether of all the fatty substances released.
These fatty substances are constituted almost entirely of combined fatty alcohols, but they may, in some cases,
contain sulphonic derivatives (true sulphonics) and fatty acids, generally in very small proportions.
2. REAGENTS
2.1 Propan-2-ol, 98
solution (viv), rendered slightly alkaline with a 0.1 N sodium hydroxide solution in the
presence of phenolphthalein.
2.2 Hydrochloric acid, = 1 .I9 g/ml) analytical reagent grade, sulphate free.
2.3 Diethyl ether.
2.4
Hydrochloric acid, approximately 1 N solution in distilled water.
2.5 Sodium sulphate, neutral and anhydrous.
3. APPARATUS
Ordinary laboratory apparatus not otherwise specified, and the following items
saponification flask, 250 ml, fitted with a condenser;
(a)
three separating funnels, 500 ml;
(6)
300 ml;
(c) conicalflask,
(d) volumetric flask, 250 ml;
round-bottomed distillation flask, 250 ml, with ground-glass neck;
(e)
fractionating column, 20 cm long, inside diameter approximately 8 mm, with a ground-glass cone at its
cf)
lower end, which can be fitted to the neck of the flask;
straight condenser, 80 cm long;
(g)
(h) glass beads;
(i) beaker, 400 ml;
analytical balance, accurate to o. 1 mg.
(j)
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ISO/R 894-1%8(E)
4. PROCEDURE
4.1 Test portion
Use the aqueous alcoholic solution, LI, resulting from the determination of matter extractable by hexane
(see Part VI of this IS0 Recommendation) and corresponding to the test portion Mo.
4.2 Determination
Reduce the solution to approximately one fifth of its volume by evaporation on the water bath, using a
current of air. Add 20 ml of propan-2-01 (2.1) and evaporate to dryness.
Dissolve, heating if necessary, in 50 ml of distilled water and transfer quantitatively to the saponification flask
by means of distilled water, bringing the final volume to approximately 100 ml. Add two glass beads and then,
very carefully, 35 ml of hydrochloric acid (2.2). (Care is necessary to avoid losses from the flask due to over-
flow of the foam resulting from decomposition of any carbonates formed during the evaporation to dryness).
Attach the condenser and reflux for at least four hours. Cool and transfer quantitatively to one of the 500 ml
separating funnels (A). Wash the condenser and flask carefully and quantitatively with diethyl ether (2.3)
and distilled water, which is then added to the liquid in the separating funnel.
,
Shake in order to homogenize thoroughly.
Add 30 nil of diethyl ether (2.3). Shake vigorously and allow to settle.
Transfer the lower layer to a second separating funnel (B). Extract once again with 30 ml of diethyl ether (2.3).
Collect the lower layer in a third separating funnel (C) and transfer the upper layer to the first separating
funnel (A).
bxtract the aqueous phase three more times, each time using 30 ml of diethyl ether (2.3)
I
Combine the ethereal phases in separating funnel (A) and transfer the aqueous phase after the last extraction
into a 400 ml beaker.
Wash funnels (B) and (C) three times, each time using 20 ml of distilled water. Add the washings to the
aqueous phase contained in the beaker.
Wash the ethereal extract three times, each time using 15 ml of dilute hydrochloric acid (2.4), and add the
washings to the aqueous phase.
Evaporate the latter on the boiling water bath to less than 200 ml, then transfer quantitatively to the 250 ml
volumetric flask. Using distilled water, dilute to the mark; the solution thus obtained, Lz , is used for the
determination of the content of combined
...