Cost Effective Quantification of Trace Level edta (Ethylene Di-amine Tetra Acetic Acid) by Titrimetry in Active Pharmaceutical Ingredients

Standardization
Accurately weigh and transfer about 0.06 g of potassium bromated into a clean and dry iodine flask. Note down the 
weight as W (g). Add about 50 ml water, 20 ml of hydrochloric acid solution and about 2.0 g potassium Iodide to the 
iodine flask and stopper immediately and allow to stand in the dark for exactly 10 minutes. Rinse the stopper and the 
inner walls of the flask with water and titrate with sodium thiosulphate solution until colour changes to pale yellow. 
Add 3 ml of starch solution as indicator and continue the titration until the blue colour is discharged. Note down the 
volume of sodium thiosulphate solution consumed in ml as V
(1) 
ml. Perform a blank titration in duplicate and note 
down the average volume of sodium thiosulphate solution consumed in ml as V
(2) 
ml.
Molarity (M)=W(g)/(V
(1)
-V
(2)
) × 0.02784
W(g)=Weight in g of potassium bromate
V
(1) 
ml=Volume in ml of sodium thiosulphate solution consumed in the titration
V
(2) 
ml=Average Volume in ml of sodium thiosulphate solution consumed in the blank titration
Repeat the mean of two values.
Note
The difference between the two values should not be more than 0.5%.Restandardize the solution as frequently as 
supported by laboratory stability data. In the absence such data, re-standardize the solution weekly. Whenever 0.01 M 
or 0.05 M or lower molar solutions required, dilute appropriately from 0.1 M and use.
 

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Nagaraju et al
Der Chemica Sinica, 2017, 8(1):175-183
Pelagia Research Library
178
Preparation of standard solution
Accurately weighed 1.5211 g of EDTA.2Na (Equivalent to 1.1948 g of EDTA) in a 250 ml volumetric flask sonic ate 
to dissolve by adding water to make up to the mark with water.