Valine
(vay' leen).
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C5H11NO2117.15
l-Valine    [72-18-4].
DEFINITION
Valine contains NLT 98.5% and NMT 101.5% of l-valine (C5H11NO2), calculated on the dried basis.
IDENTIFICATION
ASSAY
•  Procedure
Sample:  110 mg of Valine
Blank: Mix 3 mL of formic acid and 50 mL of glacial acetic acid.
Titrimetric system 
Mode: Direct titration
Titrant: 0.1 N perchloric acid VS
Endpoint detection: Potentiometric
Analysis: Dissolve the Sample in 3 mL of formic acid and 50 mL of glacial acetic acid. Titrate with the Titrant. Perform the Blank determination.
Calculate the percentage of valine (C5H11NO2) in the Sample taken:
Result = {[(VS VB) × N × F]/W} × 100
VS== Titrant volume consumed by the Sample (mL)
VB== Titrant volume consumed by the Blank (mL)
N== actual normality of the Titrant (mEq/mL)
F== equivalency factor, 117.2 mg/mEq
W== Sample weight (mg)
Acceptance criteria: 98.5%–101.5% on the dried basis
IMPURITIES
•  Residue on Ignition 281: NMT 0.1%
•  Chloride and Sulfate, Chloride 221
Standard solution: 0.50 mL of 0.020 N hydrochloric acid
Sample: 0.73 g of Valine
Acceptance criteria: NMT 0.05%
•  Chloride and Sulfate, Sulfate 221
Standard solution: 0.10 mL of 0.020 N sulfuric acid
Sample: 0.33 g of Valine
Acceptance criteria: NMT 0.03%
•  Iron 241: NMT 30 ppm
•  Heavy Metals, Method I 231: NMT 15 ppm
•  Related Compounds
System suitability solution: 0.4 mg/mL each of USP l-Valine RS and USP l-Phenylalanine RS in 0.1 N hydrochloric acid
Standard solution: 0.05 mg/mL of USP l-Valine RS in 0.1 N hydrochloric acid. [Note—This solution has a concentration equivalent to 0.5% of the Sample solution. ]
Sample solution: 10 mg/mL of Valine in 2 N hydrochloric acid
Chromatographic system 
Mode: TLC
Adsorbent: 0.25-mm layer of chromatographic silica gel mixture
Application volume: 5 µL
Developing solvent system: Butyl alcohol, glacial acetic acid, and water (3:1:1)
Spray reagent: 2 mg/mL of ninhydrin in a mixture of butyl alcohol and 2 N acetic acid (95:5)
System suitability 
Suitability requirements: The chromatogram of the System suitability solution exhibits two clearly separated spots.
Analysis 
Samples: System suitability solution, Standard solution, and Sample solution
After air-drying the plate, spray with Spray reagent, and heat between 100 and 105 for 15 min. Examine the plate under white light.
Acceptance criteria: Any secondary spot of the Sample solution is not larger or more intense than the principal spot of the Standard solution.
Individual impurities: NMT 0.5%
Total impurities: NMT 2.0%
SPECIFIC TESTS
•  Optical Rotation, Specific Rotation 781S
Sample solution: 80 mg/mL in 6 N hydrochloric acid
Acceptance criteria: +26.6 to +28.8
•  pH 791
Sample solution: 50 mg/mL of solution
Acceptance criteria: 5.5–7.0
•  Loss on Drying 731: Dry a sample at 105 for 3 h: it loses NMT 0.3% of its weight.
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in well-closed containers.
•  USP Reference Standards 11
USP l-Phenylalanine RS Click to View Structure
USP l-Valine RS Click to View Structure
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/QuestionContactExpert Committee
MonographHuy T. Dinh, M.S.
Scientific Liaison
1-301-816-8594
(DS2010) Monographs - Dietary Supplements
Reference StandardsRS Technical Services
1-301-816-8129
rstech@usp.org
USP35–NF30 Page 4991
Chromatographic Column— 
Chromatographic columns text is not derived from, and not part of, USP 35 or NF 30.