Quality control methods for

Argon-methane R. 
A suitable commercially available reagent. 
Arsenic, dilute, AsTS. One millilitre contains 10 µg of arsenic. 
Procedure. Dilute 1 ml of strong arsenic AsTS with sufficient water to produce 
100 ml.
Note. Dilute arsenic AsTS must be freshly prepared. 
Arsenic, strong, AsTS. 
Procedure. Dissolve 0.132 g of arsenic trioxide R in 6 ml of sodium hydroxide 
(∼80g/l) TS, by gentle heating. Dilute the cooled solution with 20ml of water, 
and add 50 ml of hydrochloric acid (∼250g/l) TS and sufficient water to produce 
100 ml. 
Arsenic trioxide R. As
2
O
3
. 
A suitable commercially available reagent. 
Beads for gel chromatography. 
A suitable commercially available material for gel chromatography. 
Beef extract R. A residue from beef broth obtained by extracting fresh, sound, 
lean beef by cooking with water and evaporating the resulting broth at a low 
temperature, usually under reduced pressure until a thick pasty residue is 
obtained. 
A suitable commercially available reagent. 
Benzoic acid R. C
7
H
6
O
2
. Contains not less than 99.8% of C
7
H
6
O
2
. 
Description. Colourless, light, feathery crystals or a white, microcrystalline 
powder; characteristic, faint odour. 
Solubility. Slightly soluble in water; freely soluble in ethanol (∼750g/l) TS, ether 
R, and chloroform R. 
Methanol-insoluble substances. Dissolve 20g in 200 ml of methanol R and digest 
under complete reflux for 30 minutes. Filter through a tared filtering crucible, 

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Quality control methods for medicinal plant materials 
wash thoroughly with methanol R, and dry at 105°C; leaves a residue of not 
more than 1.0 mg. 
Assay. Dissolve about 0.5 g, accurately weighed, in 15 ml of ethanol (∼750g/l) TS, 
previously neutralized to phenol red/ethanol TS, add 20ml of water and titrate 
with sodium hydroxide (0.1 mol/l) VS, using phenol red/ethanol TS as 
indicator. Repeat the operation without the substance being examined and make 
any necessary correction. Each ml of sodium hydroxide (0.1 mol/l) VS is 
equivalent to 12.21 mg of C
7
H
6
O
2
.