Quality control methods for

Phloroglucinol TS. 
Procedure. Dissolve 1 g of phloroglucinol R in 100ml of ethanol (∼750g/l) TS. 
Phosphate buffer, pH 7.4, TS. 
Procedure. Dissolve 6.8 g of potassium dihydrogen phosphate R in 250 ml of 
water and add 393.4 ml of sodium hydroxide (0.1 mol/l) VS. 
Phosphomolybdic acid R. H
3
PO
4
,12MoO
3
,24H
2
O.
A suitable commercially available reagent. 
Phosphorus pentoxide R. P
2
O
5
. 
A suitable commercially available reagent. 
Polysorbate 20 R. Quality conforms to the monograph in The international 
pharmacopoeia, Vol. 4, p. 202. 
 
Polysorbate 80 R. Quality conforms to the monograph in The international 
pharmacopoeia, Vol. 4, p. 202. 
Potassium bromide R. KBr. 
A suitable commercially available reagent. 
Potassium chlorate R. KClO
3
. 
A suitable commercially available reagent. 
Potassium dichromate R. K
2
Cr
2
O
7
. 
A suitable commercially available reagent. 
Potassium dichromate (0.0167 mol/l) VS. Potassium dichromate R, dissolved in 
water to contain 4.904g of K
2
Cr
2
O
7 
in 1000 ml.

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Quality control methods for medicinal plant materials 
Method of standardization. Ascertain the exact concentration of the 0.0167 mol/l 
solution in the following manner: Place 25.0ml of the potassium dichromate 
solution into a glass-stoppered flask. Add 2 g of potassium iodide R, dilute with 
200 ml of water, add 5 ml of hydrochloric acid (∼420g/l) TS, allow to stand for 10 
minutes in a dark place, and titrate the liberated iodine with sodium thiosulfate 
(0.1 mol/l) VS, adding 3 ml of starch TS as the end-point is approached. Correct 
for a blank determined using the same quantities of the same reagents.