Packaging and storage—
Preserve in well-closed containers.
Specific rotation 
781S
:
between
9.8
and
11.2
.
Test solution:
50 mg per mL, in 1 N hydrochloric acid.
Chloride 221—
A solution containing 0.35 g shows no more chloride than corresponds to 0.20 mL of 0.020 N hydrochloric acid (0.04%).
[NOTE—If necessary, dissolve the test specimen by heating to near boiling and adding 1 mL of nitric acid.
]
Sulfate 221—
A solution containing 1.2 g shows no more sulfate than corresponds to 0.50 mL of 0.020 N sulfuric acid (0.04%).
[NOTE—If necessary, dissolve the test specimen by heating to near boiling and adding 1 mL of 3
N hydrochloric acid.
]
Iron 241:
0.003%.
[NOTE—If necessary, use 2 mL of hydrochloric acid to dissolve the test specimen.
]
Heavy metals, Method II 231:
0.0015%.
Chromatographic purity—
Adsorbent:
0.25-mm layer of chromatographic silica gel mixture.
Diluted ammonia solution—
Transfer 16 mL of concentrated ammonia to a 100-mL volumetric flask, and dilute with water to volume.
Test solution—
Transfer about 0.1 g of Tyrosine, accurately weighed, to a 10-mL volumetric flask, dissolve in Diluted ammonia solution, and dilute with water to volume. Apply 5 µL.
Standard solution—
In a suitable flask, dissolve an accurately weighed quantity of USP L-Tyrosine RS in 1 mL of Diluted ammonia solution, and dilute with water to volume to obtain a solution having a known concentration of about 0.05 mg per mL. Apply 5 µL. [NOTE—This solution has a concentration equivalent to about 0.5% of that of the Test solution.]
System suitability solution—
Dissolve about 10 mg of USP L-Tyrosine RS and about 10 mg of USP L-Phenylalanine RS in 1 mL of Diluted ammonia solution, dilute with water to 25.0 mL, and mix. Apply 5 µL.
Spray reagent—
Dissolve 0.2 g of ninhydrin in 100 mL of a mixture of butyl alcohol and 2 N acetic acid (95:5).
Developing solvent system—
Prepare a mixture of isopropyl alcohol and ammonium hydroxide (70:30).
Procedure—
Proceed as directed for
Thin-Layer Chromatography under
Chromatography 621. Dry the plate between 100
and 105
until the ammonia disappears completely. Spray with
Spray reagent, and heat between 100
and 105
for about 15 minutes. Examine the plate under white light. The chromatogram obtained from the
System suitability solution exhibits two clearly separated spots. Any secondary spot in the chromatogram obtained from the
Test solution is not larger or more intense than the principal spot in the chromatogram obtained from the
Standard solution: not more than 0.5% of any individual impurity is found; and not more than 2.0% of total impurities is found.
Organic volatile impurities, Method IV 467:
meets the requirements.
Assay—
Transfer about 180 mg of Tyrosine, accurately weighed, to a 125-mL flask, dissolve in 6 mL of formic acid, add 50 mL of glacial acetic acid, and titrate with 0.1 N perchloric acid VS, determining the endpoint potentiometrically. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 18.12 mg of C9H11NO3.
;)
