BS EN ISO 4320:1998 download.Non-ionic surface active agents — Determination of cloud point index — Volumetric method — (ISO 4320:1977, including Erratum: 1980).
Determination of the cloud point index provides a way of characterizing weakly alkoxylated derivatives and their hydrocarbon hydrophobic groups.
This simple and rapid measurement is a valuable means for checking the level of alkoxylation of non-ionic derivatives intended, for example, for suiphonation.
1 Scope
BS EN ISO 4320 specifies a volumetric method for the determination of the cloud point index of non-ionic surface active agents.
2 Field of application
The method is applicable to weakly alkoxylated non-ionic surface active agents (1 to 5 oxyethylene groups) the hydrophobic group of which is provided by an alcohol, an alkylphenol or a fatty acid (provided that the last has a melting point lower than 30 °C), subject to the product being soluble in propan-1-ol to the extent of 1 g in 10 ml at 30 °C. It is equally applicable to lipophilic bases derived from alcohols, alkylphenols and fatty acids.
3 Reference
ISO 607, Surface active agents — Detergents — Met hods of sample division1.
4 Definition
For the purposes of BS EN ISO 4320, the following definition applies:
cloud point index
the number of millilitres of distilled water necessary to render cloudy, at a specified temperature, a solution containing a given mass of surface active agent in a given volume of solvent
5 Principle
Addition, at 30 °C, of distilled water to a propanol solution of the surface active agent until the appearance of cloudiness.
6 Reagents
6.1 Distilled water.
6.2 Propan-1-ol, complying with the following
requirements:
— assay (by gas chromatography) 99 % (rn/rn);
— density P20 0,804 to 0,805 g/ml:
— refractive index n ° 1,384 to 1,385;
— non-volatile matter < 0,005 % (in/rn);
— free acidity (expressed
as C2H5COOH) <0,01 % (rn/rn);
— water (determined by the Karl Fischer
method; see ISO 760) <0,2 Yo (rn/rn).
7 Apparatus
Ordinary laboratory apparatus, and in particular:
7.1 Beaker (see the figure) of height 80 mm and diameter 50 mm, with double walls permitting temperature stability, and having a mass less than 200 g, fitted with a polyethylene, polytetrafluoroethylene or an aluminium foil cover pierced with two holes allowing entry of the thermometer (7.2) and the burette (7.4).
7.2 Thermometer, STC/0,1/29/41, complying with
the requirements of ISOIR 654.
7.3 One-mark pipette, capacity 10 ml, complying
with the requirements of ISO 648.
7.4 Burette, capacity 50 ml, complying with the
requirements of class A of ISO 385.
7.5 Magnetic stirrer.
7.6 Bar magnet, coated with
polytetrafluoroethylene.
7.7 Water bath, with circulation, capable of being controlled to within ± 0,1 °C.
8 Sampling
The laboratory sample of the non-ionic surface active agent shall be prepared and stored according to the instructions in ISO 607.
9 Procedure
9.1 Test portion
Weigh 1,0 ± 0,1 g of the laboratory sample into the beaker (7.1), previously weighed to the nearest 0,01 g.
9.2 Determination
Add 10 ml of the propan-1-ol (6.2)to the beaker (7.1) containing the test portion (9.1). Introduce the bar magnet (7.6). place the beaker fitted with its cover on the magnetic stirrer (7.5) and insert the thermometer (7.2).
Fit the beaker (7.1) onto the water bath (7.7) and control the temperature at 30,0 ± 0,1 °C.
Start the water circulation and the stirrer (stir gently at first in order to avoid splashing the liquid on the walls of the beaker).
Ensure that the test portion is completely dissolved (the solution should be clear) and add, drop by drop, the water (6.1) from the burette (7.4) until the liquid remains cloudy.
Check that the temperature in the beaker is maintained at 30,0 ± 0,5 °C during the complete operation.
The results of the test depend upon the speed of introduction of the water. Hence, the period during which it is introduced should be between 20 and 30 mm, according to the quantity of water introduced.
Immediately after the cloud point is reached, allow the solution to equilibrate for 5 mm so as to verify that the turbidity does not disappear.
10 Expression of results
10.1 Method of calculation
The cloud point index of the product is expressed as the volume, in millilitres, of water added by the procedure specified in clause 9 to render opaque the solution of non-ionic surface active agent.
Take as the result the mean of at least three determinations, expressed to the nearest 0,05 ml (1 drop of water).
10.2 Repeatability
The maximum difference between the results of two determinations carried out in rapid succession on the same sample, by the same analyst using the same apparatus, should not exceed 2 % of the mean volume found.
10.3 Reproducibility
The difference between results obtained on the same sample in two different laboratories should not exceed 5 % of the mean volume found.
11 Test report
The test report shall include the following particulars:
a) all information necessary for the complete identification of the sample;
b) the reference to the method used:
c) the results obtained and the form in which they
are expressed;
d) the conditions of test:
— the temperature of the water bath,
— the temperature of the solution of the
product at the moment the turbidity appears,
— the time taken to dissolve the product.
— the exact length of time during which distilled water is introduced,
— the length of the determination,
— the nature of the change from clear to
cloudy, namely if the change is sharp or if there
is a state of opalescence before cloudiness,
— the mass of the test portion;
e) any operation not included in BS EN ISO 4320 or regarded as optional, as well as any incidents which may have affected the results.