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Ref. No.: IS0 / R 422 - 1965 (E)
IS0
I NT ERN AT I O NA L O RG A N 12 AT1 ON FOR STAN DARD IZ AT1 O N
IS0 RECOMMENDATION
R 422
SPECIFICATION FOR PHOTOGRAPHIC GRADE
P-METHYLAMINOPHENOL SULPHATE
1st EDITION
March 1965
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 422, Specification for Photographic Grade P-Methylamino-
phenol Sulphate, was drawn up by Technical Committee ISQ/TC 42, Photography, the
Secretariat of which is held by the American Standards Association, Inc. (ASA).
Work on this question by the Technical Committee began in 1956 and led, in 1959,
to the adoption of a Draft IS0 Recommendation.
In August 1961, this Draft IS0 Recommendation (No. 425) was circulated to all the
IS0 Member Bodies for enquiry. It was approved, subject to a few modifications of an
editorial nature, by the following Member Bodies :
Belgium Germany Romania
Brazil Italy Sweden
Canada Japan Switzerland
Chile Netherlands United Kingdom
France New Zealand U.S.A.
U.S.S.R.
No Member Body opposed the approval of the Draft.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0
Council, which decided, in March 1965, to accept it as an IS0 RECOMMENDATION.
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IS0 / R 422 - 1965 (E) -1
IS0 Recommendation R 422 March 1965
SPECIFICATION FOR PHOTOGRAPHIC GRADE
P-METHYLAMINOPHENOL SULPHATE
1. SCOPE
This IS0 Recommendation is one of a series to establish criteria of purity of chemicals suitable
for processing photographic materials. A " photographic grade " chemical is one which meets
purity requirements as described.
This specification states the purity requirements and the test methods for photographic grade
p-methylaminophenol sulphate (HOC,H,NHCH,. $$ H,SO,).
2. PHYSICAL APPEARANCE
p-methylaminophenol sulphate is in the form of white crystalline powder.
3. SUMMARY OF REQUIREMENTS
Assay: 99.0 per cent minimum, 102.0 per cent maximum by cerate titration; 97.5 per cent mini-
mum by acid titration.
Volatile matter at 105 OC: 0.3 per cent maximum.
Ash: 0.10 per cent maximum.
Heavy metals (as Pb): 0.002 per cent maximum.
Iron (Fe): 0.005 per cent maximum.
p-aminophenol: 2.5 per cent maximum.
p-amino- NN-dimethylaniline (sulphate) : To pass test.
Matter soluble in diethyl ether: 0.2 per cent maximum.
Solubility: To pass test.
Identity: To pass melting-point test. The infra-red identity test may be used as a supplemental
method.
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I
IS0 / R 422 - 1965 (E)
4. ASSAY
(by cerate titration: 99.0 per cent minimum, 102.0 per cent maximum)
(by acid titration: 97.5 per cent minimum)
4.1 Cerate titration
4.1.1 Reagent: Standard cerate solution. Mix 52 5 2 g of ammonium ceric nitrate * with
27 ml of sulphuric acid in a 600 ml beaker, with mechanical stirring. Cautiously add
distilled water in 100 ml portions, with mechanical stirring, allowing 2 to 3 min between
each portion. Continue the addition of water until the cerate is completely dissolved.
Dilute to 1 litre with distilled water and mix well.
4.1.1.1 Standardization of cerate solution. Place about 0.2 g of primary standard dry arsenic
trioxide on a 25 mm diameter watch glass and weigh accurately. Transfer the watch
glass and contents to a 250 ml conical flask. Add 15 ml of 10 per cent sodium hydroxide
solution and warm the mixture gently. When solution is complete, cool to room
temperature and add 25 ml of dilute sulphuric acid (1 + 5). Dilute to 100 ml with
distilled water. As catalyst, add 0.15 ml of 0.01 M osmium tetroxide (prepared by
dissolving 0.25 g of osmium tetroxide in 100 ml of approximately 0.1 N sulphuric
acid) and add 1 drop of ferroin indicator.
CAUTION : Osmium tetroxide is poisonous-avoid contact.
Titrate the arsenic trioxide solution with the cerate solution to be standardized, until
the reddish-orange colour changes to colourless or very pale blue. A sluggish end-
point indicates insufficient osmium tetroxide; up to 0.7 ml may be required as the
solution ages.
mass of AS,~, x 1000
--
- normality of cerate solution.
millilitres of cerate solution x 49.45
4.1.2 Procedure. Place about 0.25 g of the sample on a 25 mm diameter watch glass and weigh
accurately. Transfer the watch glass and sample to a 250 ml conical flask containing
100 ml of distilled water and 10 ml of approximately 0.1 N sulphuric acid. Dissolve the
sample, add 3 drops of ferroin indicator and titrate with the standard cerate solution to
a light-green colour which persists for 15 seconds.
1 ml O. 1 N cerate = 0.008 61 g HOC6H4NHCH,. '/2 H2S04
Nom.-This titration includes oxidizable material other than p-methylaminophenol sulphate.
4.2 Acid titration
Take about 0.6 g of the sample, weigh accurately and dissolve in 50 ml of distilled water.
Add 90 ml of neutral acetone and titrate potentiometrically with 0.1 N sodium hydroxide,
using glass and calomel electrodes. Plot the titration curve and determine the end-point.
1 ml 0.1 N NaOH = 0.01722 g HOC,H,NHCH,. '/2 H2S04
5. VOLATILE MAïTER AT 105OC
(0.3 per cent maximum)
Place 5.0 f 0.1 g of the sample in a low-form glass-stoppered weighing bottle and weigh accu-
rately. Dry at 105 "C for 4 hours. Cool in a desiccator and weigh. The loss in mass should be not
more than 0.015 g.
* Reagents used in making the tests should be recognized reagent grade chemicals normally used for careful analytical
work. In ail the directions, the acids and ammonium hydroxide referred to should be of ull strength, unless dilution is
specified. Dilution is specified in terms of normality, when standardization of the reagent is required. When dilution is
indicated as (1 +x), it means 1 volume of the reagent or strong solution diluted with x volumes of distilled water.
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IS0 / R 422 - 1965 1 (E)
6. ASH
(0.10 per cent maximum)
Incinerate 5 & 0.1 g of the sample in a tared platinum crucible and then ignite the residue at
600 f 25 "C for 4 hours. Cool in a desiccator and weigh. The residue mass should be not more
than 0.005 g.
Nom.-Save the residue for the heavy metals and iron tests.
7. HEAVY METALS (as Pb)
(0.002 per cent maximum)
Prepare a 25 ml heavy metals test control containing 0.10 mg of lead ion and a 25 ml iron test
control containing a soluble iron salt equivalent to 0.25 mg of iron (see sect
...