ISO 10348:1993

INTERNATIONAL IS0
STANDARD 10348
First edition
1993-02-01
- Processing wastes -
Photography
Determination of silver content
- Dgtermina tion de la teneur
Photographie - Effluents de traitement
en argent
Reference number
IS0 10348:-I 993(E)
- -
IS0 10348:1993(E)
Contents
Page
1 scope . 1
2 Normative references . 1
3 Principle . 2
. 2
3.1 Flame atomic absorption spectroscopy (AAS) methodology
3.2 Potentiometric titration (PT) methodology . 2
4 Reliability . 2
........................................... 2
5 Safety and operational precautions
5.1 Hazard warnings . 3
5.2 Hazard information code system . 3
.................................................................. 3
5.3 Safety precautions
..........................................................
5.4 Operational precautions 3
6 Reagents . 4
7 Glassware .
8 Sampling and sample pretreatment . 5
8.1 Sampling and preservation . 5
8.2 Sample size and pretreatment .
9 Preparation of test sample . 7
9.1 Cyanogen iodide (CNI) treatment . 7
9.2 Concentration and digestion (Digestion A) . 8
9.3 Vigorous digestion (Digestion B) . 8
10 Analysis by atomic absorption spectroscopy (AAS) . 9
................................... 9
10.1 Special apparatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
................................... 9
10.2 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
...................... 9
11 Analysis by potentiometric iodide titration PT)
11 .I Special apparatus . . . . . . . . . .~.~.~.
0 IS0 1993
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II
IS0 10348:1993(E)
11.2 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
11.3 Calculations for titration methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Annex
A Preparation of reagent solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
A.1 Preparation of cyanogen iodide solution (CNI) (DANGER: << S >>
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
) 12
A.2 Preparation of silver standard solutions (0,5 mg/l, I,0 mg/l, 3,0
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
mg/l and 5,0 mg/l) for AAS method
A.3 Preparation of silver nitrate standard solutions (0,100 mol/l, 0,010
mol/l and 0,001 mol/l) for PT methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
A.4 Preparation of potassium iodide standard solutions (0,l mol/l, 0,Ol
mol/l and 0,001 mol/l) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

IS0 10348:1993(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
(I EC) 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 10348 was prepared by Technical Committee
lSO/TC 42, Photography.
Annex A forms an integral part of this International Standard.

IS0 10348:1993(E)
Introduction
This International Standard is one of a series devoted to the analysis of
photographic wastes; it encompasses the field of analysis of silver in
photographic effluents.
Analysis for silver in photographic products and effluents presents unique
problems in sampling, handling and treatment. These problems are not
always adequately covered in standard references. It is the purpose of this
International Standard to provide methodology both for sample handling
and for the analysis of silver in effluents. Some of the chemicals specified
in the test procedures are caustic, toxic or otherwise hazardous. Specific
warning, caution and danger notices are noted for particularly hazardous
materials but normal precautions required during the performance of any
chemical procedure shall be exercised at all times.
In the case of effluents, the photographic laboratory can best establish its
conformity to regulations by appropriate chemical analysis. In some cases,
in-house analyses will be possible; often the use of an outside laboratory
will be required.
Silver in photographic processing wastes originates as a soluble thiosulfate
or other complex. Other waste components, however, may interact, re-
sulting in an unstable system containing varying amounts of soluble forms
of silver. Waste samples to be analysed for heavy metals are normally
stabilized by acidification with nitric acid. This treatment is unsatisfactory
for silver in effluents containing photographic processing wastes. Since
thiosulfate is unstable in acid solutions, the conventional treatment can
actually promote the formation of insoluble silver. Cyanogen iodide (CNI)
solution is the effective preservative for silver in these effluents?
This International Standard includes flame atomic absorption spectroscopy
(AAS) and two potentiometric iodide titration (PT) methods of analysis. The
method employed will dictate the way in which the sample is preserved
and treated. Samples to be analysed by the AAS method are normally
ready for analysis, once stabilized with CNI solution. The iodide titration
methods, however, require a digestion to solubilize the silver and remove
interfering species followed by a boiling step (for Digestion A) to concen-
trate the sample. The standard digestion methods for AK, which rec-
ommend the use of hydrochloric acid, are not suitable for the preparation
of samples for silver analysis.
I) Owerbach, D. The use of cyanogen iodide (CNI) as a stabilizing agent for silver
in photographic processing effluents. Journal of Applied photographjc Engineering,
4(l), pp. 2-24, 1978.
V
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INTERNATIONAL STANDARD IS0 10348: 1993(E)
Photography - Processing wastes - Determination
of silver content
IS0 835-l : 1981, Laboratory glassware - Graduated
1 Scope
pipettes - Part I: General requirements.
This International Standard gives methods for deter-
IS0 835-2: 1981, Laboratory glassware - Graduated
mining the silver content in photographic effluents
pipettes - Part 2: Pipettes for which no waiting time
from photographic processing wastes. Sampling, .
is specified.
sample preservation and analytical methodology are
included.
IS0 835-3: 1981, Laboratory glassware - Graduated
pipettes - Part 3: Pipettes for which a waiting time
Three analytical procedures are given with two sup-
porting sample treatment methodologies: of 15 s is specified.
IS0 835-4: 1981, Laboratory glassware - Graduated
a) a flame atomic absorption spectroscopy (MS)
pipettes - Part 4: Blow-out pipettes.
method;
IS0 1042:1983, Laboratory glassware - One-mark
b) two potentiometric iodide titration (PT) methods.
volumetric flasks.
The choice of treatment is dependent on the analysis
method and form of sample. Where MS is the cho-
IS0 3696: 1987, Water for analytical laboratory use -
sen method for analysis, cyanogen iodide-treated or
Specification and test methods.
preserved samples may be analysed directly. For the
PT method, two digestion procedures are given: Di-
IS0 4788:1980, Laboratory glassware - Graduated
gestion A for effluents with low salt content, and Di-
measuring cylinders.
gestion B for samples with high solids content.
IS0 5667-l : 1980, Water quality - Sampling -
Part 1: Guidance on the design of sampling pro-
grammes.
2 Normative references
IS0 5667-2:1991, Water quality - Sampling -
The following standards contain provisions which,
Part 2: Guidance on sampling techniques.
through reference in this text, constitute provisions
of this International Standard. At the time of publi-
IS0 5667-3: -*I Water quality - Sampling - Part 3:
cation, the editions indicated were valid. All standards
Guidance on ’ the preservation and handling of
are subject to revision, and parties to agreements
samples.
based on this International Standard are encouraged
to investigate the possibility of applying the most re-
IS0 6353-l : 1982, Reagents for chemical analysis -
cent editions of the standards indicated below.
Part 1: General test methods
Members of IEC and IS0 maintain registers of cur-
rently valid International Standards.
IS0 6353-2:1983, Reagents for chemical analysis -
Part 2: Specifications - First series.
IS0 385-l : 1984, Laboratory glassware - Burettes -
Part I: General requirements.
IS0 6353-3:1987, Reagents for chemical analysis -
Part 3: Specifications - Second series.
IS0 648: 1977, Laboratory glassware - One-mark
pipettes.
2) To be published. (Revision of IS0 5667-3:1985)

IS0 10348:1993(E)
F
is the Faraday constant;
3 Principle
is the concentration of silver ions.
%I
3.1 Flame atomic absorption spectroscopy
In the presence of an excess of iodide ions, the silver
(AAS) methodology
ion concentration, cAg, is given by
A silver-containing lamp, when heated to excitation, cAg = KSPh
generates a spectrum which includes the ultraviolet
where
emission bands of the silver atom. The silver ions in
a solution aspirated into a flame will absorb the silver
is the solubility product for silver iodide;
QP
emission bands when light from the lamp is passed
through the flame, according to a Beer’s law relation-
is the concentration of iodide ions.
Cl
ship:
A sharp change in potential is obtained during the
cAg = kmbg(+))
titration as the solution progresses from one with sil-
ver ions in excess to one with iodide ions in excess.
where
is the concentration of silver ions;
4 Reliability
z is the transmittance of light through the
The practical lower limits (approximate) for silver
flame at the specified wavelength aspir-
analyses are the following
ated with the sample;
is the transmittance of light through the
Direct flame AAS O,l mg/l
flame at the specified wavelength aspir-
PT, Digestion A (sample 500 ml;
ated with a silver-free reference sample;
titrant 0,001 mol/l potassium iodide) 02 w/l
k is a constant.
PT, Digestion B (sample I,0 ml;
100 mg/l
titrant 0,001 mol/l potassium iodide)
A calibration curve is normally generated to define the
relationship specifically.
The 20 confidence limits for Digestion A, as deter-
mined through inter-laboratory tests, are equal to
+ 0,12 mg/l for samples containing 0,2 mg/l to
3.2 Potentiometric titration (PT)
4,0 mg/l of silver in effluent samples. These results
methodology
are based on seventeen data points obtained from six
different laboratories 3) . This value is true for both
The titration of a solution containing silver ions with
potentiometric iodide titration methods using either
an iodide solution will form a precipitate of silver
the manual method (pH-meter) or the automatic
iodide in accordance with the reaction:
titrimeter method with a titrant addition rate of
0,l ml/min.
Ag’ + I- -+ Agl(solid)
The 20 confidence limits for the flame AAS method
A silver electrode, either prepared from a silver billet
are equal to + 0,007 mg/l for samples containing
(11 .I .2) or an iodide-selective electrode, with an ap-
0,02 mg/l to 0,05 mg/l of silver in photographic
propriate reference electrode will generate a potential
effluents, when directly aspirated after a five-fold
in the presence of a solution containing silver ions in
sample volume reduction.
accordance with the Nernst equation:
E = h!?O + o,023(RT/nF>~log(cAg)
5 Safety and operational precautions
where
The test procedure for silver analysis given in this
International Standard requires careful technique by
E is the measured potential, in volts;
an experienced operator. It requires care in sample
is the base potential, including the refer-
EO storage and safe handling of both the sample and re-
ence electrode contribution, in volts;
agent solutions due to the hazards and/or toxicity of
the cyanogen iodide stabilizing agent and other sol-
R is the universal gas constant;
utions. Due to the vigorous agitation and possible loss
by splashing in the potentiometric iodide titration,
T is the thermodynamic temperature;
careful monitoring of the procedure is required. The
n is the number of electrons transferred; unique requirements and the large number of items
3) For an explanation on how the data were treated, see the ASTM Handbook on Statistical Methods. Copies are available from
ASTM, 1916 Race Street, Phi
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