(Ph. Eur. monograph 2444)
DEFINITION
Mixtures of high-molecular-mass macrogols (also known as polyethylene oxides). The type of high-
molecular-mass macrogol is defined by a number that indicates the nominal average molecular mass in the range of 100 000 to 7 000 000. A suitable stabiliser (e.g. butylhydroxytoluene) and a suitable flowability
agent (e.g. silicon dioxide) may be added.
CHARACTERS
Appearance
White or almost white, free-flowing powder.
Solubility
Freely soluble in water.
mp
Minimum 65 °C.
IDENTIFICATION
A. Infrared absorption spectrophotometry (2.2.24).
Comparison high-molecular-mass macrogol CRS.
B. Viscosity (see Tests).
TESTS
Solution S
Prepare a solution of the substance to be examined in a mixture of carbon dioxide-free water R and 2-
propanol R according to Table 2444.-1.
pH (2.2.3)
6.0 to 10.0 for solution S.
Viscosity (2.2.10)
Determine the dynamic viscosity of solution S at 25 °C using a rotating viscometer and a suitable spindle.
Table 2444.-1. – Solution S and viscosity
| Nominal average molecular mass |
Composition of solution S (g of substance / mL of carbon dioxide-free water R + mL of 2- propanol R) | Dynamic viscosity (mPa·s) |
Rotation speed (r/min) |
| 100 000 | 30 g / 570 | 12 – 50 | 50 |
| 200 000 | 30 g / 570 | 65 – 115 | 50 |
| 300 000 | 30 g / 570 | 600 – 1200 | 10 |
| 400 000 | 30 g / 570 | 2250 – 4500 | 2 |
| 600 000 | 30 g / 570 | 4500 – 8800 | 2 |
| 900 000 | 30 g / 570 | 8800 – 17 600 | 10 |
| 1 000 000 | 12 g / 588 | 400 – 800 | 10 |
| 2 000 000 | 12 g / 588 | 2000 – 4000 | 10 |
| 4 000 000 | 6 g / 594 | 1650 – 5500 | 2 |
| 5 000 000 | 6 g / 594 | 5500 – 7500 | 2 |
| 7 000 000 | 6 g / 594 | 7500 – 10 000 | 2 |
Ethylene oxide (2.4.25, Method A)
Maximum 1 ppm.
Carry out the test with the following modifications.
Stock solution: Dilute 0.5 mL of ethylene oxide stock solution R2 to 10.0 mL with propanol R. Dilute 1.0 mL
of this solution to 50.0 mL with propanol R.
Test solution: Weigh 0.50 g (MT) of the substance to be examined into a 10 mL vial (other sizes may be used depending on the operating conditions). Close and allow to stand at 70 °C for 30 min.
Reference solution (a): Weigh 0.50 g (MR) of the substance to be examined into an identical 10 mL vial and add 10 μL of the stock solution. Close and homogenise, and allow to stand at 70 °C for 30 min.
Reference solution (b): To 0.50 mL of ethylene oxide solution R3 in a 10 mL vial add 0.1 mL of a freshly
prepared 10 mg/L solution of acetaldehyde R. Close and homogenise, and allow to stand at 70 °C for
30 min.
Loss on drying (2.2.32)
Maximum 1.0 per cent, determined on 1.000 g by drying in an oven at 105 °C for 45 min.
Sulfated ash
Maximum 5.0 per cent, determined on 1.00 g.
Heat a silica crucible to redness for 30 min, allow to cool in a desiccator and weigh. Evenly distribute 1.00 g
of the substance to be examined 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 type of high-molecular-mass macrogol.
