Assay of Methyldopa

Molecular Formula: C₁₀H₁₃NO₄  

Molecular Weight: 211.21 

Material Required: Methyldopa 0.2 g, anhydrous formic acid: 15 mL, glacial acetic acid: 30 mL, dioxane: 30 mL, 0.1 N perchloric acid, and crystal violet solution. 

Procedure: Weigh accurately about 0.2 g of methyldopa and dissolve in a mixture of  15 mL of anhydrous formic acid, 30 mL of glacial acetic acid, and 30 mL of dioxane. Add  0.1 mL of crystal violet solution and titrate with 0.1 N perchloric acid. Perform a blank determination and make any necessary corrections.

Reaction:

Factor calculation: 

1 mole of perchloric acid ≅ 1 mole of methyldopa 

1000 mL of 1N HClO₄ ≅ 211.21 g of C₁₀H₁₃NO₄  

1 mL of 0.1N HClO₄ ≅ 0.021121 g of C₁₀H₁₃NO₄  

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