Quality control methods for

Ethanol (∼710 g/l) TS. A solution of about 950ml of ethanol (∼750g/l) TS diluted 
with water to 1000 ml. 
Ethanol (∼375 g/l) TS. A solution of about 525ml of ethanol (∼750g/l) TS diluted 
with water to 1000 ml. 
 
Ethanol (∼188 g/l) TS. A solution of about 260m1 of ethanol (∼750g/l) TS diluted 
with water to 1000 ml. 
 
Ethanol (
∼150 g/l) TS. A solution of about 210m1 of ethanol (∼750g/l) TS diluted with 
water to 1000 ml.
Ether R. C
4
H
10
O. 
A suitable commercially available reagent. 
Ether/light petroleum TS1. 
Procedure. Dilute 60 ml of ether R with sufficient distilled light petroleum R to 
produce 1000 ml. 
 
Ether/light petroleum TS2. 
Procedure. Dilute 150ml of ether R with sufficient distilled light petroleum R to 
produce 1000 ml. 
Ether/light petroleum TS3. 
Procedure. Dilute 500 ml of ether R with sufficient distilled light petroleum R to 
produce 1000 ml. 
Ethyl acetate R. C
4
H
8
O
2
. 
A suitable commercially available reagent. 
Fast yellow R. C.I. 13015; E105; C
12
H
9
N
3
Na
2
O
6
S
2
.
Description. An orange-yellow to red powder. 
Solubility. Freely soluble in water; slightly soluble in ethanol (∼750g/l) TS; 
practically insoluble in ether R and chloroform R. 
A suitable commercially available reagent. 
Ferric ammonium sulfate R. FeH
4
NO
8
S
2
,12H
2
O. This reagent should be free of 
chlorides. 
A suitable commercially available reagent. 
Ferric ammonium sulfate (0.25 mol/l) VS. Ferric ammonium sulfate R, 
dissolved in nitric acid (∼750 g/l) TS to contain 120.5 g of . FeH
4
NO
8
S
2
,12H
2
O
in 
1000 ml.
Procedure. Dissolve 120.5 g of ferric ammonium sulfate R in a sufficient quantity 
of nitric acid (∼750g/l) TS to produce 1000ml. The reagent should be free of 
chlorides.