Method
for the estimation of Levo dopa content
Reagent Required:
Anhydrous
formic acid, Anhydrous glacial acetic
acid , Dioxan , 0.1M Perchloric acid,
Crystal
violet indicator (0.5% w/v solution in Anhydrous glacial acetic acid)
Glass wares and
Apparatus Required:
250mL
conical flask, Burette
Procedure:
Weigh accurately about 0.3gm of sample
dissolve, heating if necessary, in 5 ml of Anhydrous formic acid and add 25 ml
of anhydrous glacial acetic acid and 25 ml
of dioxin. Titrate with 0.1M Perchloric acid,
Using 0.1 ml of crystal violet indicator and
titrating to a green end-point. Carry out a blank titration.
1
ml of 0.1M Perchloric acid is equivalent to 0.01972 g of C9H11NO4.
Calculation:
Percentage
of Levo dopa is calculated as:
Titre X 0.01972 x Normality x 100
= -----------------------------------------------------
Weight of sample X 0.1
Method for
preparation of 0.1M Perchloric acid:
Mix
8.5 ml of Perchloric acid with 500 ml of anhydrous glacial acetic acid and 25
ml of acetic anhydride, cool and add anhydrous glacial acetic acid to produce
1000 ml.
Standardization:
Weigh
accurately about 0.35 gm of potassium hydrogen phthalate, previously powdered
lightly and dried at 1200 C for 2 hours and dissolve it in 50 ml of
anhydrous glacial acetic acid. Add 0.1 ml of crystal violet solution and
titrate with the Perchloric acid solution until the violet colour change to
emerald-green. Perform a blank determination and make any necessary correction.
(1
ml of 0.1M Perchloric acid is equivalent to 0.02042 gm of C8H5KO4.)
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