Quality control methods for

Indian ink see Chinese ink TS. 
Indophenol blue R. C.I. 49700; C
18
H
26
N
2
O.
Description. A violet-black powder. 
Solubility. Practically insoluble in water; soluble in chloroform R. 
Homogeneity. Carry out the method for thin-layer chromatography, using silica 
gel G as the coating substance and dichloromethane R as the mobile phase. 
Apply 10 µl of a 0.1 mg/ml solution in dichloromethane R and develop. After 
removing the plate from the chromatographic chamber allow it to dry in air. 
Only one spot appears on the chromatogram. 
A suitable commercially available reagent. 
Iodine R. I
2
. 
A suitable commercially available reagent. 
Iodine TS. 
Procedure. Dissolve 2.6 g of iodine R and 3 g of potassium iodide R in sufficient 
water to produce 100 ml (approximately 0.1 mol/l). 
 
Iodine (0.1 mol/l) VS. Iodine R and potassium iodide R, dissolved in water to 
contain 25,38g of I
2
and 36.0 g of KI in 1000 ml. 
Method of standardization. Ascertain the exact concentration of the 0.1 mol/l 
solution by titrating 25.0 ml with sodium thiosulfate (0.1 mol/l) VS, using starch 
TS as indicator. 

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Quality control methods for medicinal plant materials 
Iodine (0.02 mol/l) VS. Iodine R and potassium iodide R, dissolved in water to 
contain 5.076g of I
2
and 7.2g of KI in 1000 ml. 
Method of standardization. Ascertain the exact concentration of the solution 
following the method described under iodine (0.l mol/l) VS. 
Iodine/ethanol TS. 
Procedure. Dissolve 10g of iodine R in sufficient ethanol (∼750g/l) TS to produce 
1000 ml. 
Iron(III) citrate R. Ferric citrate, C
6
H
5
FeO
7
, H
2
O. A suitable commercially 
available reagent. 
Lactic acid R. C
3
H
6
O
3
. Quality conforms to the monograph in The international 
pharmacopoeia, Vol. 4, p. 115.