Lysine Hydrochloride Tablets
Lysine Hydrochloride Tablets contain NLT 90.0% and NMT 120.0% of the labeled amount of C6H14N2O2·HCl, as l-lysine hydrochloride.
•  A. Thin-Layer Chromatographic Identification Test
Standard solution:  0.4 mg/mL of USP l-Lysine Hydrochloride RS in water
Sample solution:  A filtered solution in water, equivalent to 0.4 mg/mL of lysine hydrochloride from powdered Tablets
Chromatographic system 
Mode:  TLC
Adsorbent:  0.25-mm layer of chromatographic silica gel
Application volume:  10 µL
Developing solvent system:  Isopropyl alcohol and ammonium hydroxide (70:30)
Spray reagent:  2 mg/mL of ninhydrin in a mixture of butyl alcohol and 2 N acetic acid (95:5)
Samples:  Standard solution and Sample solution
Develop the plate, and dry at 100–105 until the ammonia disappears completely. Spray with Spray reagent, and heat at 100–105 for 15 min. Examine the plate under white light.
Acceptance criteria:  The RF value of the principal spot from the Sample solution corresponds to that from the Standard solution.
•  Procedure
Sample:  A portion of the powder from NLT 20 finely powdered Tablets, equivalent to 75 mg of lysine hydrochloride
Blank:  Proceed as directed in the Analysis without the Sample.
Titrimetric system 
Mode:  Direct titration
Titrant:  0.1 N perchloric acid VS
Endpoint detection:  Potentiometric or visual
Analysis:  Dissolve the Sample in 5 mL of mercuric acetate TS with gentle heating. Cool, then add 50 mL of glacial acetic acid. Add 3 drops of crystal violet TS when needed. Titrate with Titrant. Perform the Blank determination.
Calculate the percentage of the labeled amount of l-lysine hydrochloride (C6H14N2O2·HCl) in the portion of 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, 91.33 mg/mEq
W== nominal amount of l-lysine hydrochloride in the Sample taken (mg)
Acceptance criteria:  90.0–120.0%
•  Disintegration and Dissolution 2040: Meet the requirements for Disintegration
Time:  20 min
•  Weight Variation 2091: Meet the requirements
•  Packaging and Storage: Preserve in well-closed containers, and store at controlled room temperature.
•  USP Reference Standards 11
USP l-Lysine Hydrochloride RS
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Topic/Question Contact Expert Committee
Monograph Natalia Davydova
Scientific Liaison
(DS2010) Monographs - Dietary Supplements
Reference Standards RS Technical Services
USP35–NF30 Page 1375
Pharmacopeial Forum: Volume No. 30(5) Page 1665