Monosodium Glutamate
(mon'' oh soe' dee um gloo' ta mate).
Monosodium Glutamate contains NLT 99.0% and NMT 100.5% of C5H8NNaO4·H2O.
•  A.
Sample solution:  1 in 30
Analysis:  To 1 mL of the Sample solution add 1 mL of ninhydrin TS and 100 mg of sodium acetate, and heat in a boiling water bath for 10 min.
Acceptance criteria:  An intense, violet blue color is formed.
•  B.
Sample solution:  1 in 10
Analysis:  To 10 mL of the Sample solution add 5.6 mL of 1 N hydrochloric acid.
Acceptance criteria:  A white, crystalline precipitate of glutamic acid is formed on standing. Precipitation is promoted by agitation. When 6 mL of 1 N hydrochloric acid is added to the turbid solution, the glutamic acid dissolves on stirring.
•  C. Identification Tests—General, Sodium 191: It meets the requirements of the pyroantimonate precipitate test.
•  Procedure
Sample:  250 mg
Titrimetric system 
Mode:  Direct titration
Titrant:  0.1 N perchloric acid VS
Blank:  100 mL of glacial acetic acid with a few drops of water
Endpoint detection:  Potentiometric
Analysis:  Wet the Sample with a few drops of water. Dissolve in 100 mL of glacial acetic acid. Titrate with 0.1 N perchloric acid VS. Perform a blank determination.
Calculate the percentage of monosodium glutamate (C5H8NNaO4·H2O) in the Sample taken:
Result = [(V B) × N × F × 100]/W
V== volume of Titrant consumed by the Sample (mL)
B== volume of Titrant consumed by the Blank (mL)
N== actual normality of the Titrant (mEq/mL)
F== equivalency factor, 93.56 mg/mEq
W== weight of the Sample (mg)
Acceptance criteria:  99.0%–100.5%
•  Chloride and Sulfate, Chloride 221: A 280-mg portion shows no more chloride than corresponds to 1.0 mL of 0.020 N hydrochloric acid (0.25%).
•  Lead 251: NMT 10 ppm
•  Heavy Metals, Method II 231: NMT 20 ppm
•  Clarity and Color of Solution
Sample solution:  1.0 g in 10 mL of water
Standard solution:  To 0.2 mL of a solution of sodium chloride containing 10 µg/mL of chloride ion (Cl), add 20 mL of water, and mix. Then add 1 mL of 5 N nitric acid, 0.2 mL of dextrin solution (1 in 50), and 1 mL of silver nitrate TS, and allow to stand for 15 min.
Analysis:  Compare the Sample solution with the Standard solution (see Spectrophotometry and Light-Scattering—Visual Comparison 851).
Acceptance criteria:  The Sample solution is colorless and has no more turbidity than the Standard solution.
•  Optical Rotation, Specific Rotation 781S
Sample solution:  100 mg/mL in 2 N hydrochloric acid
Acceptance criteria:  +24.8 to +25.3, determined at 20
•  pH 791: 6.7–7.2, in a solution (1 in 20)
•  Loss on Drying 731: Dry a sample at 100 for 5 h: it loses NMT 0.5% of its weight.
•  Packaging and Storage: Preserve in tight containers.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Robert H. Lafaver, M.S.
Scientific Liaison
(EXC2010) Monographs - Excipients
USP35–NF30 Page 1872
Pharmacopeial Forum: Volume No. 28(3) Page 826