ISO 3626:1996
(Main)Photography — Processing chemicals — Specifications for potassium thiocyanate
Photography — Processing chemicals — Specifications for potassium thiocyanate
Photographie — Produits chimiques de traitement — Spécifications relatives au thiocyanate de potassium
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Standards Content (Sample)
INTERNATIONAL
STANDARD
Second edition
1996-I O-l 5
Photography - Processing chemicals -
Specifications for potassium thiocyanate
Photographie - Produits chimiques de traitemen t - Spbifica tions
rela ties au thiocyana te de potassium
Reference number
IS0 3626:1996(E)
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IS0 3626: 1996(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
technical committees. Each member body interested in a subject for
which a technical committee has been established has the right to be
represented on that committee. International organizations, governmental
and non-governmental, in liaison with ISO, also take part in the work. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 3626 was prepared by Technical Committee
ISO/TC 42, Photography.
This second edition cancels and replaces the first edition (IS0 3626:1976),
which has been technically revised.
0 IS0 1996
All rights reserved. Unless otherwise specified, no part of this publication may be
reproduced or utilized in any form or by any means, electronic or mechanical, including
photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
ii
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@ IS0
IS0 3626: 1996(E)
Introduction
0.1 This International Standard is one of a series that establishes criteria
of purity for chemicals used in processing photographic materials. General
test methods and procedures cited in this International Standard are
compiled in parts 1, 5 and 6 of IS0 10349.
This International Standard is intended for use by individuals with a
working knowledge of analytical techniques, which may not always be the
case. Some of the procedures utilize caustic, toxic or otherwise hazardous
chemicals. Safe laboratory practice for the handling of chemicals requires
the use of safety glasses or goggles, rubber gloves and other protective
apparel such as face masks or aprons where appropriate. Normal
precautions required in the performance of any chemical procedure are to
be exercised at all times but care has been taken to provide warnings for
hazardous materials. Hazard warnings designated by a letter enclosed in
angle brackets “( )” are used as a reminder in those steps detailing
handling operations and are defined in IS0 10349-I. More detailed
information regarding hazards, handling and use of these chemicals may
be available from the manufacturer.
0.2 This International Standard provides chemical and physical
requirements for the suitability of a photographic-grade chemical. The
tests correlate with undesirable photographic effects. Purity requirements
are set as low as possible consistent with these photographic effects.
These criteria are considered the minimum requirements necessary to
assure sufficient purity for use in photographic processing solutions,
except that if the purity of a commonly available grade of chemical
exceeds photographic processing requirements and if there is no
economic penalty in its use, the purity requirements have been set to take
advantage of the availability of the higher-quality material. Every effort has
been made to keep the number of requirements to a minimum. Inert
impurities are limited to amounts which will not unduly reduce the assay.
All tests are performed on samples “as received” to reflect the condition
of materials furnished for use. Although the ultimate criterion for suitability
of such a chemical is its successful performance in an appropriate use
test, the shorter, more economical test methods described in this
International Standard are generally adequate.
Assay procedures have been included in all cases where a satisfactory
method is available. An effective assay requirement serves not only as a
safeguard of chemical purity but also as a valuable complement to the
identity test. Identity tests have been included whenever a possibility
exists that another chemical or mixture of chemicals could pass the other
tests.
All requirements listed in clause 4 are mandatory. The physical appearance
of the material and any footnotes are for general information only and are
not part of the requirements.
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IS0 3626: 1996(E) @ IS0
0.3 Efforts have been made to employ tests which are capable of being
run in any normally equipped laboratory and, wherever possible, to avoid
tests which require highly specialized equipment or techniques.
Instrumental methods have been specified only as alternative methods or
alone in those cases where no other satisfactory method is available.
Over the past few years, great improvements have been made in
instrumentation for various analyses. Where such techniques have
equivalent or greater precision, they may be used in place of the tests
described in this International Standard. Correlation of such alternative
procedures with the given method is the responsibility of the user. In case
of disagreement in results, the method called for in the specification shall
prevail. Where a requirement states “to pass test”, however, alternative
methods shall not be used.
iv
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IS0 3626:1996(E)
INTERNATIONAL STANDARD @ IS0
Processing chemicals - Specifications for
Photography -
potassium thiocyanate
I Scope
This International Standard establishes criteria for the purity of photographic-grade potassium thiocyanate and
specifies the test methods to be used to determine the purity.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain
registers of currently valid International Standards.
Photographic-grade chemicals - Test methods - Part I: General.
IS0 10349-I : 1992, Photography -
IS0 10349-5: 1992, Photography - Photographic-grade chemicals - Test methods - Part 5: Determination of
heavy metals and iron con tent.
Photographic-grade chemicals - Test methods - Part 6: Determination of
IS0 10349-6: 1992, Photography -
halide con tent.
3 General
3.1 Physical properties
Potassium thiocyanate (KCNS) exists as colourless, deliquescent crystals. It has a relative molecular mass of 97,18.
3.2 Hazardous properties
Potassium thiocyanate presents no special hazardous problems under normal handling.
3.3 Storage
Store in a cool dry place. Care shall be taken to avoid conditions of high heat and/or humidity which can cause
decomposition and emission of toxic fumes.
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IS0 3626: 1996(E)
4 Requirements
A summary of the requirements is shown in table 1.
5 Reagents and materials, including glassware
All reagents, materials and glassware shall conform to the requirements specified in IS0 10349-I unless otherwise
noted. The hazard warning symbols used as a reminder in those steps detailing handling operations are defined in
IS0 10349-I. These symbols are used to provide information to the user and are not meant to provide
conformance with hazardous labelling requirements, as these vary from country to country.
6 Sampling
See IS0 10349-I.
7 Test procedures
7.1 Assay
7.1.1 Specification
Content of KCNS shall be 98,0 % (m/m) min.
Table 1 - Summary of requirements
International Standard in
Limit Subclause
Test
which test method is given
7.1 IS0 3626
Assay 98,0 % (LIZ/~) min.
7.2 IS0 10349-5
Heavy metals content (as Pb) 0,002 % (ITZ/ITZ) max.
0,000 2 % (&Tz) max. 7.3 IS0 10349-5
Iron content
Halide content (as Cl-) 0,05 % (IIZ/IPZ) max. 7.4 IS0 10349-6
7.5 IS0 3626
pH value 5,3 to 8,7
7.6 IS0 3626
Sulfur compounds
a) For developer solution, use
amount precipitated by
7.6.1 IS0 3626
ammoniacal silver nitrate 0,001 % (LTZ/VZ) max.
b) For fixer solution, use
7.6.2
iodine consumption To pass test IS0 3626
7.7
Sulfate content (as SO& 0,06 % (VZ/ITZ) max. IS0 3626
7.8 IS0 3626
Copper content 0,000 1 % (r&2) max.
Clear and free from insoluble matter 7.9 IS0 3626
Appearance of aqueous solution
except for a slight flocculence
7.10 IS0 3626
Appearance of ethanolic solution Clear and free from insoluble matter
except for a slight flocculence
NOTE -m/m = mass/mass
2
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0 IS0
IS0 3626: 1996(E)
7.1.2 Reagents
7.1.2.1 Nitric acid (HNO$, (I + 9) solution 1).
7.1.2.2 Ammonium iron(W) sulfate [(NHa)Fe(SO&], 50 g/l solution.
7.1.2.3 Silver nitrate (AgNO$, standard volumetric solution of 0,100 mol/l (17,O g/l) 2) 3).
7.1.2.4 Ammonium thiocyanate (NHaSCN), standard volumetric solution of 0,100 mol/l (7,61 g/l) 2).
7.1.3 Apparatus
7.1.3.1 Burette, of 50 ml capacity.
7.1.3.2 Pipette, of 50 ml capacity.
7.1.4 Procedure
Weigh, to the nearest 0,001 g, a test portion of about 0,3 g and dissolve it in 50 ml of water. Add 5 ml of the nitric
acid (7.1.2.1), followed by 50,OO ml of the silver nitrate (7.1.2.3) using the pipette (7.1.3.2). Shake well, add 2 ml of
the ammonium iron(lll) sulfate (7.1.2.2) and titrate the excess of silver nitrate with the ammonium thiocyanate
(7.1.2.4) to a permanent red endpoint.
7.1.5 Expression of results
The assay, expressed as a percentage by mass of KCNS, is given by
9,718(50-q - Vq)/m
is the actual concentration, in moles per litre, of the silver nitrate (7.1.2.3);
Cl
is the actual concentration, in moles per litre, of the ammonium thiocyanate (7.1.2.4);
e2
V is the volume, in millilitres, of the ammonium thiocyanate (7.1.2.4) used for the titration;
m is the mass, in grams, of the test portion;
...
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