EN ISO 11348-3:1998

SLOVENSKI STANDARD
SIST EN ISO 11348-3:2000
01-januar-2000
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Water quality - Determination of the inhibitory effect of water samples on the light
emission of Vibrio fischeri (Luminescent bacteria test) - Part 3: Method using freeze-dried
bacteria (ISO 11348-3:1998)
Wasserbeschaffenheit - Bestimmung der Hemmwirkung von Wasserproben auf die
Lichtemission von Vibrio fischeri (Leuchtbakterientest) - Teil 3: Verfahren mit
gefriergetrockneten Bakterien (ISO 11348-3:1998)
Qualité de l'eau - Détermination de l'effet inhibiteur des échantillons d'eau sur la
luminescence de Vibrio fischeri (Essai de bactéries luminescentes) - Partie 3: Méthode
utilisant des bactéries lyophilisées (ISO 11348-3:1998)
Ta slovenski standard je istoveten z: EN ISO 11348-3:1998
ICS:
13.060.70 Preiskava bioloških lastnosti Examination of biological
vode properties of water
SIST EN ISO 11348-3:2000 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 11348-3:2000

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SIST EN ISO 11348-3:2000

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SIST EN ISO 11348-3:2000

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SIST EN ISO 11348-3:2000

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SIST EN ISO 11348-3:2000
INTERNATIONAL ISO
STANDARD 11348-3
First edition
1998-12-15
Water quality — Determination of the
inhibitory effect of water samples on the
light emission of Vibrio fischeri
(Luminescent bacteria test) —
Part 3:
Method using freeze-dried bacteria
Qualité de l’eau — Détermination de l’effet inhibiteur d’échantillons d’eau
sur la luminescence de Vibrio fischeri (Essai de bactéries luminescentes) —
Partie 3: Méthode utilisant des bactéries lyophylisées
A
Reference number
ISO 11348-3:1998(E)

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SIST EN ISO 11348-3:2000
ISO 11348-3:1998(E)
Contents
Page
1  Scope. 1
2  Normative references. 1
3  Principle . 2
4  Interferences. 2
5  Reagents and materials. 2
6  Apparatus. 3
7  Sampling and sample pretreatment . 3
8  Procedure . 4
9  Evaluation . 5
10  Expression of results. 7
11  Criteria of validity . 8
12  Precision . 8
13  Test report. 8
Annex A Colour-correction method . 9
Annex B Dilution level D — Preparation of the dilution series. 12
Annex C Precision data. 13
©  ISO 1998
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 • CH-1211 Genève 20 • Switzerland
Internet iso@iso.ch
Printed in Switzerland
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SIST EN ISO 11348-3:2000
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ISO ISO 11348-3:1998(E)
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 collab-
orates 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 ISO 11348-3 was prepared by Technical Committee
ISO/TC 147, Water quality, Subcommittee SC 5, Biological methods.
ISO 11348 consists of the following parts, under the general title Water
quality — Determination of the inhibitory effect of water samples on the
light emission of Vibrio fischeri (Luminescent bacteria test) :
— Part 1: Method using freshly prepared bacteria
— Part 2: Method using liquid-dried bacteria
— Part 3: Method using freeze-dried bacteria
Annexes A, B and C of this part of ISO 11348 are for information only.
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SIST EN ISO 11348-3:2000
©
ISO 11348-3:1998(E) ISO
Introduction
Measurements according to this International Standard can be carried out
using freshly prepared bacteria, as well as freeze-dried or liquid-dried
bacterial preparations.
Standardized work carried out by DIN NAW WI and
ISO/TC 147/SC 5 WG 1 has shown that in special cases these different
techniques may give different results, especially where water samples
contain heavy metals.
Such varying sensitivity is caused by differences in media composition
used in the preparation of freeze-dried or liquid-dried bacteria. These
protective media influence the bioavailability of toxicants and/or the light
emission of luminescent bacteria. This means that the origin and type of
preparation need to be taken into account when interpreting the results.
This can be difficult sometimes, as freeze-dried and liquid-dried bacteria
may be obtained from different suppliers. This in turn can mean that the
composition is not known in detail or cannot be revised by the user.
That is why in this International Standard, in addition to toxicity
measurements with liquid-dried bacteria (ISO 11348-2) and freeze-dried
bacteria (ISO 11348-3), a procedure with freshly prepared bacteria is
described (ISO 11348-1), the performance of which can be revised by the
user in every detail.
The laboratories responsible for the results have the opportunity to select
the most suitable technique based on expert judgement and information
about the water sample to be tested.
iv

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SIST EN ISO 11348-3:2000
©
INTERNATIONAL STANDARD  ISO ISO 11348-3:1998(E)
Water quality — Determination of the inhibitory effect of water
Vibrio fischeri
samples on the light emission of (Luminescent
bacteria test) —
Part 3:
Method using freeze-dried bacteria
1  Scope
ISO 11348 describes three methods for determining the inhibition of the luminescence emitted by the marine
bacterium Vibrio fischeri (NRRL B-11177). This part of ISO 11348 specifies a method using freeze-dried bacteria.
This method is applicable to:
— waste water,
— aqueous extracts and leachates,
— fresh waters (surface or ground waters) or salt and brackish waters, especially the monitoring of changes in
inhibition towards bacteria,
— pore water.
2  Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this part of
ISO 11348. At the time of publication, the editions indicated were valid. All standards are subject to revision, and
parties to agreements based on this part of ISO 11348 are encouraged to investigate the possibility of applying the
most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid
International Standards.
ISO 5667-16:1998, Water quality — Guidance on biotesting of samples.
1)
ISO 7027: — , Water quality — Determination of turbidity.

1)  To be published. (Revision of ISO 7027:1990)
1

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ISO 11348-3:1998(E)
3  Principle
The inhibition of light emission by cultures of Vibrio fischeri is determined by means of a batch test. This is
accomplished by combining specified volumes of the test sample or the diluted sample with the luminescent
bacteria suspension in a cuvette. The test criterion is the decrease of the luminescence, measured after a contact of
15 min and 30 min, or optionally 5 min, taking into account a correction factor (f ), which is a measure of intensity
kt
changes of control samples during the exposure time. The inhibitory effect of the water sample can be determined
as LID (see annex B) or as EC and/or EC values by means of a dilution series.
20 50
The dilution level resulting in < 20 % of inhibition of light emission is determined. For higher levels of inhibition the
dilution-effect relationship can be determined graphically or by statistical analysis. The inhibition by a sample is
expressed as the dilutions which result in 20 % and 50 % light reduction compared to the blank (EC and EC ).
20 50
These values are interpolated within the dilution series.
4  Interferences
Insoluble, slightly soluble or volatile substances or substances which react with the dilution water or the test
suspension, or alter their state during the test period, may affect the result or impair the reproducibility of the test
results.
Losses of luminescence caused by light absorption or light scattering may occur in the case of strongly coloured or
turbid waters. This interference sometimes can be compensated, e.g. by using a double-chambered absorption
correction cuvette (see annex A).
Since oxygen at . 0,5 mg/l is required for the bioluminescence, samples with a high oxygen demand (and/or a low
oxygen concentration) may cause a deficiency of oxygen and be inhibitory.
An organic contamination of the sample by readily biodegradable nutrients (e.g. urea, peptone, yeast extract,
usually > 100 mg/l) may cause a pollutant-independent reduction in bioluminescence.
Salt concentrations in the initial sample exceeding 30 g/l NaCl or contents of other compounds giving equal
osmolarity may lead, together with the salt spiking required by the test, to hyperosmotic effects. If the sample
contains between 20 g/l and 50 g/l NaCl-equivalents, no salt shall be added. The resulting concentration in the test
samples shall not exceed the osmolarity of a 35 g/l sodium chloride solution.
5  Reagents and materials
Chemicals of recognized analytical grade quality shall be used. Water shall be distilled or of equivalent purity.
5.1  Test bacteria
Strain of luminescent bacteria belonging to the species Vibrio fischeri NRRL B-11177. The bacterial suspensions
used for toxicity measurements are prepared from commercially available freeze-dried reagents which can be
stored in a freezer at 218 °C to 220 °C. The bacteria start glowing immediately after reconstitution and are ready to
be used for the test.
5.2  Sodium chloride solution, as diluent
Dissolve 20 g of sodium chloride (NaCl) in water and make up to 1 litre with water.
5.3  Sodium hydroxide solution, c(NaOH) = 1 mol/l
5.4  Hydrochloric acid, c(HCl) = 1 mol/l
NOTE  For the adjustment of the pH it may be necessary to use acids or bases of lower or higher concentration.
2

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ISO 11348-3:1998(E)
5.5  Solution for freeze-dried bacteria
— 20,0 g Sodium chloride (NaCl)
— 2,035 g Magnesium chloride hexahydrate (MgCl ·6H O)
2 2
— 0,30 g Potassium chloride (KCl)
Dissolve in water and make up to 1 litre with water. The solution can be stored in a freezer at 220 °C.
5.6  Reference substances
— Zinc sulfate heptahydrate (ZnSO ·7H O)
4 2
— 3,5-Dichlorophenol (CHOCl)
6 4 2
— Potassium dichromate (K Cr O )
2 2 7
6  Apparatus
6.1  Freezer for the storage of preserved bacteria.
6.2  Refrigerator to maintain the stock suspension at a temperature of 3 °C – 3 °C.
6.3  Thermostatically controlled thermoblock to maintain the test samples at a temperature of 15 °C – 1 °C.
Within one test the temperature deviation shall be at most – 0,2 °C.
6.4  Luminometer, measuring cell maintained at 15 °C – 1 °C, equipped with suitable cuvettes.
6.5  Test tubes (vials), made of a chemically inert material, appropriate for the selected luminometer and having a
capacity which facilitates the taking of a reading over the largest possible surface area.
6.6  pH-meter.
6.7  Chronometer.
6.8  Piston pipettes for plastic syringes, nominal capacity 10 μl, 500 μl and 1 000 μl.
6.9  Piston pipettes with variable volume, 10 ml to 200 ml and 200 μl to 5 000 μl.
6.10  Refrigerated centrifuge.
6.11  Conductometer.
7  Sampling and sample pretreatment
7.1  Sampling
Sampling shall be conducted in chemically inert, clean containers in accordance with ISO 5667-16. Fill the
containers completely and seal them. Test the samples as soon as possible after collection. Where necessary,
store samples at a temperature of 2 °C to 5 °C in the dark in glass for not longer than 48 h. For periods up to two
weeks, store at 20 °C. Do not use chemicals to preserve the samples. Perform the necessary pH adjustment and
2
salt addition just before testing.
3

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7.2  Sample preparation
Measure the pH of all samples. If the pH lies between 6 and 8,5 there is generally no adjustment necessary. pH-
adjustment, however, may alter the nature of the sample. On the other hand, the pH of the sample and the pH of the
test batch may differ because of the buffer capacity of the test medium. It may be necessary to carry out tests on
both the pH-adjusted and the non-pH-adjusted samples.

If necessary, adjust the pH of the samples to 7,0 – 0,2 by adding either hydrochloric acid (5.4) or sodium hydroxide
(5.3); choose the concentration of the hydrochloric acid or the sodium hydroxide to restrict the volume added to not
more than 5 % of total volume.
Add 20 g of sodium chloride per litre to the water sample or to the neutralized water sample. For brackish and saline
waters, measure the salinity and calculate the amount of NaCl (if any) required to adjust the osmolarity (clause 4).
Strongly turbid samples should be allowed to sediment for 1 h or centrifuged, for example for 10 min at 5 000 g, or
should be filtered.
8  Procedure
8.1  Preparation of stock suspensions
8.1.1  Initial preparations
Prepare the samples according to 7.2.
Prepare the dilution series required (see annex B).
For control samples, maintain the NaCl solution (5.2) at 15 °C – 1 °C.
Maintain the test tubes containing controls, the samples of the dilution series and the diluent (5.2) at 15 °C – 1 °C.
Remove the vial of the freeze-dried culture from the -20 °C freezer immediately before reconstitution in water. For
the reconstitution, cool 1 ml of distilled water in a glass test tube to 3 °C – 3 °C.
Pour this volume of cooled water all at once into the lyophilized bacteria in the vial, thereby minimizing cell damage
during the rehydration process.
Since it is important that water is added quickly to allow the bacteria to come into contact with the water suddenly,
do not use a pipette. The exact volume of water is not critical.
This reconstituted luminescent bacteria suspension serves as a stock suspension; it shall be stored at 3 °C – 3 °C.
The stock suspension can be used for testing purposes as long as the validity criteria stated in clause 11 are met.
Refrozen, rehydrated bacteria can be used for preliminary tests only.
After a waiting time of at least 5 min, prepare the test suspensions from the stock suspension.
8.1.2  Variant A
Prepare the test suspensions directly in the test tubes.
Add 10 μl aliquots of the stock suspension to 500 μl of the solution (5.5), contained in cuvettes maintained at
15 °C – 1 °C, at the same intervals as for later intensity measuremen
...