详情
Ascorbic Acid
Vitamin C; L-Ascorbic Acid OH OH
H C6H8O6 Formula wt **6.*3 INS: **0 CAS: [******7]
DESCRIPTION
Ascorbic Acid occurs as white or slightly yellow crystals or as
powder. It melts at about **0c It gradually darkens on exposure to
light, is reasonably stable in air when dry, but rapidly
deteriorates in solution in the presence of air. One gram is
soluble in about 3 mL of water and in about *0 mL of alcohol. It is
insoluble in chloroform and in ether.
Function Antioxidant; meat-curing aid; nutrient.
REQUIREMENTS
Identification
A. A 1:*0 aqueous solution slowly reduces alkaline cupric tartrate
TS at *5c but more readily upon heating.
B. The infrared absorption spectrum of a potassium bromide
dispersion of the sample exhibits maxima at the same wavelengths as
those of a similar preparation of USP Ascorbic Acid Reference
Standard.
Assay Not less than *9.0% and not more than **0.5% of C6H8O6.
Lead Not more than 2 mg/kg.
Optical (Specific) Rotation Between **0.5c nd **1.5c
Residue on Ignition Not more than 0.1%.
TESTS
Assay Dissolve about **0 mg of sample, accurately weighed, in a
mixture of **0 mL of water, recently boiled and cooled, and *5 mL
of 2 N sulfuric acid. Titrate the solution immediately with 0.1 N
iodine, adding starch TS near the endpoint. Each milliliter of 0.1
N iodine is equivalent to 8.**6 mg of C6H8O6.
Lead Determine as directed in the Flame Atomic Absorption
Spectrophotometric Method under Lead Limit Test, Appendix IIIB,
using a **-g sample.
Optical (Specific) Rotation Determine as directed under Optical
(Specific) Rotation, Appendix IIB, using a solution containing 1 g
of sample in *0 mL of carbon dioxide-free water.
Residue on Ignition Determine as directed under Residue on
Ignition, Appendix IIC, igniting a *-g sample.
Packaging and Storage Store in tight, light-resistant containers.
