Appearance White crystalline powder Identification Positive Color of solution Clear, GY4 max Assay 99-100.5% PH 8.0-9.5 Related substances One: 0.5% max Others: 0.25% max Sulphate 0.02% max metals 0.002% max Selenium 0.003% max Solubility Easily soluble in water,slightly soluble in ethyl alcohol Water 6.0-8.0%

Appearance white or almost white crystalline Assay, （AgNO3 Titration method） ≥98.0% Identification A:Developing colour reaction: Crroesponds B:Developing colour reaction: Crroesponds C: Developing colour reaction: Crroesponds Acidity(PH) 6.0-7.0 Water 6.0%max Residue on igition Max 0.5% Microbial potency(anhydrous) 780u/mg

Appearance A white or light yellow powder, odorless, hygroscpic Identification A,B,C The positive reaction Soluility Very soluble in water, insoluble in acetone,chloroform,ether PH 5.5-7.5 Loss on drying 8.0% max Assay 600 I.U/mg min(dry)

Appearance White crystalline powder Assay 99.0-100.5%min Melting point 128-132℃ Specific optical rotation -15.7˚~-17.3˚ Residue on ignition 0.1% max Loss on drying 0.5%max metals 20ppm max Absence of reducing substance Accords with the specification Clarity and color of the solution Accords with the specification

Appearance white crystalline powder Optical Rotation -96˚~~ -106˚ metals Not more than 10ppm Arsenic Not more than 2ppm Loss on drying Not more than 5% Residue on Ignition Not more than 0.5% Assay Not less than 98.0%

Appearance A white crystalline powder Assay 98.0% to 101.0% Melting point About 185℃ Identification IR Similar with the Reference Spectrum Optical Rotation -15.5°～-17.5° Clearity and color of solution Clear and colourless Metals Not more than 10ppm Arsenic Not more than 2ppm Related Substances Total Not more than 2.0% GSSG Not more than 1.5% Loss on Drying Not more than 0.5% Residue on Ignition Not more than 0.1%

Appearance White or almost white crystalline powder Assay, dry base 99.0-101.0% Identification Melting point: 169.0-172.0 IR: per the spectrum of CRS TLC: As per BP2002 Chemical test: give reaction of primary Aromatic amines Appearance of solution The solution is clear and not more intensely colored than ref. solution Y5,BY5 or GY5 Acidity 0.3ml of 0.1M NaOH Related substances by TLC 0.5% max metals 20ppm max Loss on drying 0.5% max Sulfated ash 0.1% max

BP/EP/USP，99%

Description A white or almost white crystalline powder Identification Conform with spectrum off the reference standard Enantiomer ≤0.50% Related substance 5-Flucytosine ≤0.20% Total impurities ≤1.0% Residual solvents Ethanol ≤0.50% Dichloromethane ≤0.06% DMF ≤0.088% Ethyl acetate ≤0.50% Toluene ≤0.089% Residue on ignition ≤0.20% Specific optical rotation -133゜～-143゜ Water ≤0.50% Metal ≤20ppm Loss on drying ≤1.0% Assay 98.0%-102.0%

Assay 99% Boiling point 528.7 oC at 760 mmHg Appearance White villous crystallization

Appearance White or yellowish white ，crystalline powder or colourless or almost colourless crystals Solubility Slightly soluble in water ，very slightly soluble in ethanol（96%）.It is freely soluble indilute mineral acids. Identification A．IR IR spectrum is concordant with Methyldopa CRS. B.Enantiomeric purity D-Methyldopa not more than 0.5% Appearance of solution Not more intensely coloured than reference solution BY6 or B6. Acidity (0.1M NaOH) Not more than 0.5ml/g. Absorbance(on anhydrous basis) 122~137 Related substances Impurity A Not more than 0.15% Impurity B Not more than 0.15% Impurity C Not more than 0.15% Unspecified impurities Not more than 0.05% Total impurities Not more than 0.5%

Appearance White or pale yellow amorphous powder Solubility Practical insoluble in water,very soluble in ethanol(96%),slightly soluble in hexane Identification Conforms Appearance of solution Clear,color ≤GY5 Related Substances Method A Impurity A ≤1.5% Impurity B ≤0.5% Impurity C ≤1.5% Impurity D ≤2.5% Impurity E+F ≤1.7% Impurity G ≤1.5% Impurity L ≤0.5% Any other individual impurity before impurity G ≤0.5% Method B Impurity H+I ≤1.0% Impurity J ≤0.5% Impurity K ≤0.5% Any other individual impurity after impurity G ≤0.5% Total impurity ≤7.0% metals ≤ 20ppm Water ≤ 1.3% Sulphated Ash ≤0.2% Assay(on the anhydrous basis) 92.0%~~102.0% Antioxidant Assay 0.3%~~0.6% Residual Solvents Methanol ≤3000ppm Ethanol ≤5000ppm Dichloromethane ≤600ppm Propenol ≤50ppm Triethylamine ≤320ppm N-Heptane ≤5000ppm Methylcyclohexane ≤1180ppm 1,4-Dioxane ≤380 Butyl Ac3tate ≤5000ppm Dinethyl Sulfixide ≤5000ppm