(al' a neen).
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C3H7NO2 89.09
l-Alanine     [56-41-7].
Alanine contains NLT 98.5% and NMT 101.5% of C3H7NO2, as l-alanine, calculated on the dried basis.
•  Procedure
Sample:  80 mg of Alanine
Titrimetric system 
Mode:  Direct titration
Titrant:  0.1 N perchloric acid VS
Endpoint detection:  Potentiometric
Blank:  3 mL of formic acid in 50 mL of glacial acetic acid
Analysis:  Dissolve the Sample in a mixture of 3 mL of formic acid and 50 mL of glacial acetic acid, and titrate with 0.1 N perchloric acid VS. Calculate the percentage of C3H7NO2 in the portion taken:
Result = [(V B) × N × F × 100]/W
V== Sample titrant volume (mL)
B== Blank titrant volume (mL)
N== titrant normality (mEq/mL)
F== equivalency factor: 89.09 mg/mEq
W== weight of the Sample (mg)
Acceptance criteria:  98.5%–101.5% on the dried basis
Inorganic Impurities 
•  Residue on Ignition 281: NMT 0.15%
•  Chloride and Sulfate, Chloride 221: A 1.0-g portion shows no more chloride than corresponds to 0.70 mL of 0.020 N hydrochloric acid (0.05%).
•  Chloride and Sulfate, Sulfate 221: A 1.0-g portion shows no more sulfate than corresponds to 0.30 mL of 0.020 N sulfuric acid (0.03%).
•  Iron 241: NMT 30 ppm
•  Heavy Metals, Method I 231: NMT 15 ppm
Organic Impurities 
•  Procedure
Adsorbent:  0.25-mm layer of chromatographic silica gel mixture
Standard solution:  0.05 mg/mL of USP l-Alanine RS. [Note—This solution has a concentration equivalent to 0.5% of that of the Sample solution. ]
System suitability solution:  0.4 mg/mL each of USP l-Alanine RS and USP Glycine RS
Sample solution:  10 mg/mL of Alanine
Spray reagent:  2 mg/mL of ninhydrin in a mixture of butyl alcohol and 2 N acetic acid (95:5)
Developing solvent system:  Butyl alcohol, glacial acetic acid, and water (60:20:20)
Application volume:  5 µL
Samples:  Standard solution, System suitability solution, and Sample solution
Proceed as directed for Chromatography 621, Thin-Layer Chromatography. After air-drying the plate, repeat the development process. After air-drying a second time, spray with Spray reagent, and heat to 100–105 for 15 min. Examine the plate under white light. The chromatogram obtained from the System suitability solution exhibits two clearly separated spots.
Acceptance criteria 
Individual impurities:  Any secondary spot of the Sample solution is not larger or more intense than the principal spot of the Standard solution, NMT 0.5%
Total impurities:  NMT 2.0%
•  Optical Rotation, Specific Rotation 781S: +13.7 to +15.1
Sample solution:  100 mg/mL in 6 N hydrochloric acid
•  pH 791: 5.5–7.0, in a solution (1 in 20)
•  Loss on Drying 731: Dry a sample at 105 for 3 h: it loses NMT 0.2% of its weight.
•  Packaging and Storage: Preserve in tight containers, and store at controlled room temperature.
•  USP Reference Standards 11
USP l-Alanine RS Click to View Structure
USP Glycine RS Click to View Structure
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Huy T. Dinh, M.S.
Scientific Liaison
(DS2010) Monographs - Dietary Supplements
Reference Standards RS Technical Services
USP35–NF30 Page 2081
Pharmacopeial Forum: Volume No. 27(5) Page 2973