ISO 7760:2001

INTERNATIONAL ISO
STANDARD 7760
Second edition
2001-12-15
Photography — Processing waste —
Determination of hydroquinone
Photographie — Effluents de traitements — Dosage de l'hydroquinone

Reference number
©
ISO 2001
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ii © ISO 2001 – All rights reserved

Contents Page
Foreword.iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Principle.1
4 Reactions.2
5 Safety and operational precautions.2
6 Materials and reagents.3
7 Apparatus.5
8 Sampling and sample preparation.5
9 Procedure.6
10 Expression of results.6
11 Test report.7
Bibliography.8

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO 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. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
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.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 7760 was prepared by Technical Committee ISO/TC 42, Photography.
This second edition cancels and replaces the first edition (ISO 7760:1986), of which it constitutes a technical
revision.
iv © ISO 2001 – All rights reserved

Introduction
This International Standard is one of a series devoted to the analysis of photographic wastes; it encompasses the
field of analysis of the hydroquinone content in a photographic effluent.
This International Standard is intended for use by individuals with a working knowledge of analytical techniques.
Some of the procedures use caustic, toxic, or otherwise hazardous chemicals. Safe laboratory practice for the
handling of chemicals requires the use of safety glasses or goggles and, in some cases, other protective apparel
such as rubber gloves, face masks, or aprons. Normal precautions for the safe performance of any chemical
procedure must be exercised at all times, but specific details have been provided for hazardous materials. Hazard
warnings are designated by a letter enclosed in angle brackets "〈〉". These are defined in clause 5 and then used
throughout the text. More detailed information on hazards, handling, and use of these chemicals may be available
from the manufacturer.
Photographic laboratories can establish conformity to effluent regulations only by chemical analysis. If this cannot
be done in-house, an outside laboratory should be used.

INTERNATIONAL STANDARD ISO 7760:2001(E)

Photography — Processing waste — Determination of
hydroquinone
1 Scope
This International Standard specifies a spectrophotometric method for the determination of hydroquinone in
photographic processing waste.
This method can be applied to samples containing hydroquinone in the concentration range of 200 µg/l to
4 000 µg/l; aminophenols and phenylenediamines should also be determined by this method. However, sulfonated
hydroquinones or products from the further oxidation of benzoquinone will not be determined.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 648:1977, Laboratory glassware — One-mark pipettetes.
ISO 1042:1998, Laboratory glassware — One-mark volumetric flasks.
ISO 5667-1:1980, Water quality — Sampling — Part 1: Guidance on the design of sampling programmes.
ISO 5667-2:1991, Water quality — Sampling — Part 2: Guidance on sampling techniques.
ISO 5667-3:1994, Water quality — Sampling — Part 3: Guidance on the preservation and handling of samples.
ISO 6353-1:1982, Reagents for chemical analysis — Part 1: General test methods.
ISO 6353-2:1983, Reagents for chemical analysis — Part 2: Specifications — First series.
ISO 6353-3:1987, Reagents for chemical analysis — Part 3: Specifications — Second series.
ISO 10349-1:1992, Photography — Photographic-grade chemicals — Test methods — Part 1: General.
3 Principle
The hydroquinone (together with some other organic compounds) is extracted at a slightly acidic pH from the
aqueous sample with 1-pentanol. The extracted hydroquinone is then reacted under alkaline conditions with
1-ethylquinaldinium iodide solution. The absorbance of the coloured complex that is formed is then measured.
4 Reactions
5 Safety and operational precautions
5.1 Hazard warnings
Some of the chemicals specified in the test procedures are caustic, toxic or otherwise hazardous. Safe laboratory
practice for the handling of chemicals requires the use of safety glasses or goggles and, in some cases, other
protective apparel such as rubber gloves, face masks, and aprons. Specific danger notices are given in the text and
footnotes for particularly dangerous materials, but normal precautions are required during the performance of any
chemical procedure at all times.
The first time that a hazardous material is noted in the test procedures, the hazard will be indicated by the word
"DANGER" followed by a symbol consisting of angle brackets "〈 〉" containing a letter that designates the specific
hazard. A double bracket "〈〈 〉〉" will be used for particularly perilous situations. In subsequent statements involving
handling of these hazardous materials, only the hazard symbol consisting of the brackets and letter(s) will be
displayed. Furthermore, for a given material, the hazard symbols will be used only once in a single paragraph.
Hazard warning symbols will not be used for common organic solvents when used in quantities of less than 1 litre,
unless they are particularly hazardous.
2 © ISO 2001 – All rights reserved

Detailed warnings for handling chemicals and their diluted solutions are beyond the scope of this International
Standard.
Employers shall provide training and health and safety information in conformance with legal
requirements.
The hazard code system used in this International Standard is intended to provide information to the users and is
not meant for compliance with any legal requirements for labelling, as these vary from country to country.
It is strongly recommended that anyone using these chemicals obtain pertinent information from the
manufacturer about the hazards, handling, use and disposal of these chemicals.
5.2 Hazard information code system
〈B〉 Harmful if inhaled. Avoid breathing dust, vapour, mist or gas. Use only with adequate ventilation.
〈C〉 Harmful if contact occurs. Avoid contact with eyes, skin or clothing. Wash thoroughly after handling.
〈F〉 Will burn. Keep away from heat, sparks and open flame. Use with adequate ventilation.
〈O〉 Oxidizer. Contact with other material may cause fire. Do not store near combustible materials.
〈S〉 Harmful if swallowed. Wash thoroughly after handling. If swallowed, obtain medical attent
...