L-Cysteine Hydrochloride Monohydrate CAS 7048-04-6 Assay 98.5~101.0% (Titration on Dried Basis) Factory

L-Cysteine Hydrochloride Monohydrate (CAS: 7048-04-6) AJI97 Test Method
Identification: Compare the infrared absorption spectrum of the sample with that of the standard by potassium bromide disc method.
Specific Rotation [α]D20: Dried sample, C=8, 1mol/L HCl
State of Solution (Transmittance): 1.0g in 10ml of H2O, spectrophotometer, 430nm, 10mm cell thickness.
Chloride (Cl): 350mg, B-2
Ammonium (NH4): A-1
Sulfate (SO4): 1.2g, (1), ref: 0.50ml of 0.005mol/L H2SO4
Iron (Fe): 1.5g, ref: 1.5ml of Iron Std. (0.01mg/ml)
Heavy Metals (Pb): 2.0g, (1), pH=7, ref: 2.0ml of Pb Std. (0.01mg/ml)
Arsenic (As2O3): 2.0g, (1), ref: 2.0ml of As2O3 Std.
Other Amino Acids: Test Sample: 50μg, B-6-a, control; L-Cys·HCl·H2O 0.25μg
Loss on Drying: In vacuum, P2O5, at room temperature for 20 hours.
Residue on Ignition (Sulfated): AJI Test 13
Assay: Dried sample, 250mg, 0.05mol/L I2 1ml=15.762mg C3H7NO2S·HCl
pH Test: 1.0g in 100ml of H2O

L-Cysteine Hydrochloride Monohydrate (CAS: 7048-04-6) USP35 Test Method
DEFINITION
Cysteine Hydrochloride is L-Cysteine Hydrochloride Monohydrate and contains NLT 98.5% and NMT 101.5% of L-Cysteine Hydrochloride (C3H7NO2S·HCl), calculated on the dried basis.
IDENTIFICATION
A. INFRARED ABSORPTION <197K>
ASSAY
PROCEDURE
Sample: 250 mg of Cysteine Hydrochloride
Blank: Proceed as directed in the Analysis without the Sample.
Titrimetric system
(See Titrimetry <541>)
Mode: Residual titration
Titrant: 0.1 N iodine VS
Back titrant: 0.1 N sodium thiosulfate VS
Endpoint detection: Visual
Analysis: Transfer the Sample to an iodine flask. Add 20.0 mL of water and 4 g of potassium iodide, and mix. Cool the solution in an ice bath, and add 5 mL of 3 N hydrochloric acid and 25.0 mL of 0.1 N iodine VS. Insert the stopper, and allow to stand in the dark for 20 min. Titrate the excess iodine with the Back titrant. Add 3 mL of star ch TS as the endpoint is approached. Per form the Blank determination. Calculate the percentage of cysteine hydrochloride (C3H7NO2S·HCl) in the Sample taken:
Result = {[(VB − VS) × N × F]/W} × 100
VB = Back titrant volume consumed by the Blank (mL)
VS = Back titrant volume consumed by the Sample (mL)
N = actual normality of the Back titrant (mEq/mL)
F= equivalency factor, 157.6 mg/mEq
W= Sample weight (mg)
Acceptance criteria: 98.5%~101.5% on the dried basis
IMPURITIES
RESIDUEON ON IGNITION <281>: NMT 0.4%
CHLORIDE AND SULFATE, Sulfate <221>
Standard solution: 0.10 mL of 0.020 N sulfuric acid
Sample: 0.33 g of Cysteine Hydrochloride
Acceptance criteria: NMT 0.03%
IRON <241>: NMT 30ppm
HEAVY METALS, Method I <231>: NMT 15ppm
RELATED COMPOUNDS
N-Ethylmaleimide solution: 40 mg/mL of N-ethylmaleimide in alcohol
Standard stock solution: Dissolve 20 mg of USP L-Cysteine Hydrochloride RS in 10.0 mL of water. Add 10.0 mL of N-Ethylmaleimide solution, and mix. Allow the solution to stand for 5 min before using.
Standard solution: 0.05 mg/mL from Standard stock solution in water. [ NOTE-This solution has a concentration equivalent to 0.5% of that of the Sample solution.]
System suitability solution: Transfer 10 mg of USP L-Tyrosine RS and 10 mL of the Standard stock solution to a 25-mL volumetric flask. Dilute with water to volume.
Sample stock solution: Transfer 0.2 g of Cysteine Hydrochloride to a 10-mL volumetric flask, dissolve, and dilute with water to volume.
Sample solution: To 5.0 mL of the Sample stock solution add 5.0 mL of N-Ethylmaleimide solution, and mix. Allow the solution to stand for 5 min before using.
Chromatographic system (See Chromatography <621>, Thin-Layer Chromatography.)
Mode: TLC
Adsorbent: 0.25-mm layer of chromatographic silica gel mixture
Application volume: 5μL
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 2N acetic acid (95:5)
System suitability
Suitability requirements: The chromatogram of the System suitability solution exhibits two clearly separated spots.
Analysis
Samples: Standard solution, System suitability 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: +5.7° to +6.8°
LOSSON DRYING <731>: Dry a sample at room temperature at a pressure not exceeding 5 mm of mer cury for 24 h: it loses 8.0%~12.0% of its weight.
ADDITIONAL REQUIREMENTS
PACKAGING AND STORAGE: Preserve in well-closed containers.
USP REFERENCE STANDARDS <11>
USP L-Cysteine Hydrochloride RS
USP L-Tyrosine RS