Quality control methods for

 
2-Propanol R. Isopropyl alcohol; C
3
H
8
O.
A suitable commercially available reagent. 
 
Propylene glycol R. Propane diol, C
3
H
8
O
2
.
A suitable commercially available reagent. 
 
Pyridine R. C
5
H
5
N. 
A suitable commercially available reagent. 
Quinine hydrochloride R. C
20
H
24
N
2
O
2
,HCl,2H
2
O. Quality of substance 
conforms to the monograph in The international pharmacopoeia, vol. 2, p. 248. 
Saponin R. 
A suitable commercially available reference material. 
 
Silica gel R. 
A suitable commercially available material for column chromatography. 
 
Silica gel, desiccant, R. 
Description. An amorphous, partly hydrated SiO
2
, occurring in glassy granules of 
varying sizes. It is frequently coated with a substance that changes colour when 
the capacity to absorb water is exhausted. Such coloured products may be 
regenerated (i.e., may regain their capacity to absorb water) by heating at 110°C 
until the gel assumes the original colour. 
Loss on drying. Ignite 2 g, accurately weighed, at 950 ± 50°C to constant weight; 
the loss is not more than 60 mg/g. 
Water absorption. Place about 10 g in a tared weighing-bottle, and weigh. Then 
place the bottle, with the cover removed, for 24 hours in a closed container in 
which 80% relative humidity is maintained by being in equilibrium with sulfuric 
acid having a relative density of 1.19. Weigh again; the increase in weight is not 
less than 310 mg/g. 
A suitable commercially available reagent. 
Silver nitrate R. AgNO
3
. 
A suitable commercially available reagent.