Quality control methods for

Glycerol R. Propane- 1,2,3-triol with small amounts of water, C
3
H
8
O
3
. Contains 
not less than 970g/kg of C
3
H
8
O
3
. 
Description. A clear, almost colourless, syrupy and hygroscopic liquid; odourless. 
Miscibility. Miscible with water and ethanol (∼750g/l) TS; practically immiscible 
with ether R and chloroform R. 
Mass density (ρ
20
). Not less than 1.256kg/l.
Refractive index
. Not less than 1.469.
)
(
20
D
n
Acrolein and other reducing substances. Mix 1 ml with 1 ml of ammonia (∼100g/l) 
TS and heat in a water-bath at 60°C for 5 minutes; the liquid is not coloured 
yellow. Remove from the water-bath and add 3 drops of silver nitrate (40g/l) TS; 
the liquid does not become coloured within 5 minutes. 
Sulfated ash. Not more than 0.5 mg/ml. 
A suitable commercially available reagent. 
Glycerol-ethanol TS. 
Procedure. Mix equal volumes of glycerol R, water and ethanol (∼750g/l) TS. 
Glycine R. Aminoacetic acid, C
2
H
5
NO
2
.
A suitable commercially available reagent. 
 
Helium R. He. Contains not less than 999.95 ml of He per litre.
A suitable commercially available reagent. 
 
Hexane R. n-Hexane, C
6
H
14
. 
Description. A colourless, mobile, highly inflammable liquid. 
Boiling range. Distils completely over a range of 1°C between 67.5 and 69.5°C. 
Mass density (ρ
20
). 0.658-0.659kg/l. 
Refractive index (
). 1.374-1.375. 
20
D
n
A suitable commercially available reagent. 
 
Hide powder R. 
A suitable commercially available reference material.