Proline
(proe' leen).

C5H9NO2 115.13
l-Proline     [147-85-3].
DEFINITION
Proline contains NLT 98.5% and NMT 101.5% of l-proline (C5H9NO2), calculated on the dried basis.
IDENTIFICATION
ASSAY
•  Procedure
Sample:  100 mg of Proline
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 proline (C5H9NO2) in the Sample taken:
Result = {[(VS VB) × N × F]/W} × 100
 VS = = volume of Titrant consumed by the Sample (mL) VB = = volume of Titrant consumed by the Blank (mL) N = = actual normality of the Titrant (mEq/mL) F = = equivalency factor, 115.1 mg/mEq W = = Sample weight (mg)
Acceptance criteria:  98.5%–101.5% on the dried basis
IMPURITIES
NMT 0.4%
Standard solution:  0.50 mL of 0.020 N hydrochloric acid
Sample:  0.73 g of Proline
Acceptance criteria:  NMT 0.05%
Standard solution:  0.10 mL of 0.020 N sulfuric acid
Sample:  0.33 g of Proline
Acceptance criteria:  NMT 0.03%
•  Iron 241: NMT 30 ppm
NMT 15 ppm
•  Related Compounds
System suitability solution:  0.4 mg/mL each of USP l-Proline RS and USP l-Threonine RS in 0.1 N hydrochloric acid
Standard solution:  0.05 mg/mL of USP l-Proline RS in 0.1 N hydrochloric acid. [Note—This solution has a concentration equivalent to 0.5% of that of the Sample solution. ]
Sample solution:  10 mg/mL of Proline in 0.1 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
Sample solution:  40 mg/mL in water
Acceptance criteria:  84.3 to 86.3
Dry a sample at 105 for 3 h: it loses NMT 0.4% of its weight.
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in well-closed containers.
USP l-Proline RS
USP l-Threonine RS
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
1-301-816-8594
(DS2010) Monographs - Dietary Supplements
Reference Standards RS Technical Services
1-301-816-8129
rstech@usp.org
USP35–NF30 Page 4437