Edition: BP 2025 (Ph. Eur. 11.6 update)
(Ph. Eur. monograph 2730)
DEFINITION
Mixture of ethers of mixed macrogols with linear and branched fatty alcohols, mainly C₁₃H₂₈O. It contains a variable quantity of free C₁₃H₂₈O and it may contain free macrogols. The number of moles of ethylene oxide reacted per mole of branched C₁₃H₂₈O is 3 or 4 (nominal value).
CHARACTERS
Appearance: Colourless liquid.
Solubility: Practically insoluble in water, soluble or dispersible in ethanol (96 per cent), practically insoluble in light petroleum.
IDENTIFICATION
A. Gas chromatography (2.2.28).
Test solution: Dissolve 0.200 g of the substance to be examined in acetone R and dilute to 10.0 mL with the same solvent.
Reference solution: Dissolve 0.35 g of lauryl alcohol R, 0.35 g of tridecyl alcohol R, 0.15 g of myristyl alcohol R and 0.15 g of ethylene glycol monododecyl ether R in acetone R and dilute to 100.0 mL with the same solvent. Dilute 1.0 mL of the solution to 10.0 mL with acetone R.Column:
material: fused silica;
size: l = 30 m, Ø = 0.25 mm;
stationary phase: methylpolysiloxane R (film thickness 0.25 µm).
Carrier gas: hydrogen for chromatography R or helium for chromatography R.
Flow rate: 1 mL/min.
Split ratio: 1:50.
Temperature:
| Time (min) | Temperature (°C) |
|---|---|
| 0 – 1 | 120 |
| 1 – 24 | 120 → 350 |
| 24 – 34 | 350 |
Injection port: 300 °C
Detector: 350 °C
Detection: Flame ionisation.
Injection: 1 µL.
Retention time:
Lauryl alcohol = about 6.7 min;
Tridecyl alcohol = about 7.8 min;
Myristyl alcohol = about 9 min;
Ethylene glycol monododecyl ether = about 9.3 min.
System suitability (Reference solution):
resolution: minimum 5 between the peaks due to myristyl alcohol and ethylene glycol monododecyl ether.
Results:
The sum of the areas of the peaks eluting between the peak due to lauryl alcohol and the peak due to tridecyl alcohol is greater than the area of the peak due to tridecyl alcohol and the area of the peak due to lauryl alcohol.
B. Hydroxyl value (see Tests).
C. Iodine value (see Tests).
D. Saponification value (see Tests).
E. Dissolve or disperse 0.1 g in 5 mL of ethanol (96 per cent) R. Add 10 mL of dilute hydrochloric acid R, 10 mL of barium chloride solution R1 and 10 mL of a 100 g/L solution of phosphomolybdic acid R. A precipitate is formed.
TESTS
Appearance of solution: The solution is not more intensely coloured than reference solution BY5 (2.2.2, Method II). Dissolve 5.0 g in ethanol (96 per cent) R and dilute to 50 mL with the same solvent.
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 1.0, determined on 5.0 g.
Hydroxyl value (2.5.3, Method A): See Table 2730.-1.
Table 2730.-1
| Ethylene oxide units per molecule (nominal value) | Hydroxyl value |
|---|---|
| 3 | 165 – 185 |
| 4 | 145 – 160 |
Iodine value (2.5.4): Maximum 2.0.
Saponification value (2.5.6): Maximum 3.0, determined on 10.0 g.
Ethylene oxide and dioxan (2.4.25): Maximum 1 ppm of ethylene oxide and 10 ppm of dioxan.
Water (2.5.12): Maximum 3.0 per cent, determined on 2.00 g.
Sulfated ash (2.4.14): Maximum 0.2 per cent.
Ignite a silica crucible at 600 ± 50 °C for 30 min, allow to cool in a desiccator over a suitable desiccant and weigh. Evenly distribute 1.0 g in the crucible and weigh. Dry at 100-105 °C for 1 h and ignite in a muffle furnace at 600 ± 25 °C until the substance is thoroughly charred. Carry out the test for sulfated ash (2.4.14) on the residue obtained, starting from “Moisten the substance to be examined…”.
STORAGE
In an airtight container.
LABELLING
The label states the number of moles of ethylene oxide reacted per mole of C₁₃H₂₈O (nominal value).
