(Ph. Eur. monograph 1443)
Action and use
Non-ionic surfactant.
DEFINITION
Mixture of mainly mono- and diesters of polyoxyethylene glycerol ethers mainly with caprylic (octanoic) and capric (decanoic) acids. The average number of moles of ethylene oxide reacted per mole of substance is 6.
Macrogol 6 glycerol caprylocaprate may be obtained by ethoxylation of glycerol and esterification with distilled coconut or palm kernel fatty acids, or by ethoxylation of mono- and diglycerides of caprylic and capric acids.
CHARACTERS
Appearance
Pale yellow liquid.
Solubility
Partly soluble in water, freely soluble in castor oil, in glycerol, in isopropanol and in propylene glycol.
Viscosity
About 145 mPa·s.
IDENTIFICATION
A. Dissolve 1.0 g in 99 g of a mixture of 10 volumes of 2-propanol R and 90 volumes of water R. Heat the solution obtained to about 40 °C. A turbidity is produced. Allow to cool until the turbidity disappears. The cloud point is between 15 °C and 35 °C.
B. Saponification value (see Tests).
C. Composition of fatty acids (see Tests).
TESTS
Appearance
The substance to be examined is clear (2.2.1) and not more intensely coloured than reference solution Y2 (2.2.2, Method I).
Alkalinity
Dissolve 2.0 g in a hot mixture of 10 mL of ethanol (96 per cent) R and 10 mL of water R. Add 0.1 mL of bromothymol blue solution R1. Not more than 0.5 mL of 0.1 M hydrochloric acid is required to change the colour of the indicator to yellow.
Acid value (2.5.1)
Maximum 5.0, determined on 5.0 g.
Hydroxyl value (2.5.3, Method A)
165 to 225.
Saponification value (2.5.6)
85 to 105, determined on 2.0 g.
Composition of fatty acids
Gas chromatography (2.4.22, Method A).
Composition of the fatty-acid fraction of the substance:
caproic acid: maximum 2.0 per cent;
caprylic acid: 50.0 per cent to 80.0 per cent;
capric acid: 20.0 per cent to 50.0 per cent;
lauric acid: maximum 3.0 per cent;
myristic acid: maximum 1.0 per cent.
Ethylene oxide and dioxan (2.4.25)
Maximum 1 ppm of ethylene oxide and maximum 10 ppm of dioxan.
Water (2.5.12)
Maximum 1.0 per cent, determined on 1.00 g.
Total ash (2.4.16)
Maximum 0.3 per cent.
