L-Cystine
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|
C6H12N2O4S2
240.3 |
56-89-3 |
DEFINITION |
Cystine contains not less
than 98.5 per cent and not more than the equivalent of 101.0
per cent of (R,R)-3,3’-dithiobis
(2-aminopropionic acid), calculated with
reference to the dried substance.
|
CHARACTERS
|
A white, crystalline powder,
practically insoluble in water and in alcohol. It
dissolves in dilute solutions of alkali hydroxides.
|
|
IDENTIFICATION |
Infrared absorption
spectrophotometry |
TESTS |
Appearance
of solution |
Clear and
meets the requirements |
Specific
optical rotation |
-218º to -224º |
Ninhydrin-positive
substances |
Meets the requirements |
Chlorides |
Limit: 200 ppm |
Sulphates |
Limit: 300 ppm |
Ammonium |
Limit:200 ppm |
Iron |
Limit:10 ppm |
Heavy
metals |
Limit:10 ppm |
Loss
on drying |
Not more than 0.5 per
cent |
Sulphated
ash |
Not more than 0.1 per
cent |
ASSAY |
98.5 per cent to 101.0 per
cent |
STORAGE |
Store in a well-closed
container, protected from light. |