SIST EN ISO 19020:2017
(Main)Microbiology of the food chain - Horizontal method for the immunoenzymatic detection of staphylococcal enterotoxins in foodstuffs (ISO 19020:2017)
Microbiology of the food chain - Horizontal method for the immunoenzymatic detection of staphylococcal enterotoxins in foodstuffs (ISO 19020:2017)
This standard describes the detection of staphylococcal enterotoxin for dairy products and other matrices
Mikrobiologie der Lebensmittelkette - Horizontales Verfahren für den immunenzymatischen Nachweis von Staphylokokken-Enterotoxinen in Lebensmitteln (ISO 19020:2017)
Dieses Dokument legt ein Screening-Verfahren für den Nachweis von den Staphylokokken-Enterotoxinen SEA, SEB, SECs, SED und SEE (SEA bis SEE) in Lebensmitteln fest. Die Norm besteht aus zwei Hauptschritten (i) die Extraktion gefolgt von der Konzentration, was auf dem Dialyseprinzip beruht und (ii) ein immunenzymatischer Nachweis unter Anwendung handelsüblicher Nachweiskits.
Diese Internationale Norm ist anwendbar für das Screening von Staphylokokken-Enterotoxinen (SEA-SEE) in Produkten bestimmt für den menschlichen Verzehr.
Andere Staphylokokken-Enterotoxine, wie z. B. die Arten SEG, SEH, SEI, SER, SES und SET, können auch Krankheiten verursachen. Doch aufgrund fehlender handelsüblicher Nachweiskits richtet sich diese Norm nur an die Arten SEA bis SEE.
Microbiologie de la chaîne alimentaire - Méthode horizontale de détection des entérotoxines staphylococciques par test immuno-enzymatique dans les aliments (ISO 19020:2017)
L'ISO 19020:2017 décrit une méthode de recherche pour la détection des entérotoxines staphylococciques SEA, SEB, SEC, SED et SEE dans les aliments. Elle se compose de deux étapes principales: a) une extraction suivie d'une concentration basée sur le principe de la dialyse; et b) une détection immuno-enzymatique au moyen de trousses de détection disponibles dans le commerce.
L'ISO 19020:2017 s'applique à la recherche des entérotoxines staphylococciques SEA à SEE dans les produits destinés à la consommation humaine.
D'autres entérotoxines staphylococciques, telles que les types SEG, SEH, SEI, SER, SES et SET, peuvent également provoquer des intoxications alimentaires. En raison de l'absence de trousses de détection disponibles dans le commerce, l'ISO 19020:2017 ne s'applique qu'aux types SEA à SEE, mais peut s'appliquer à d'autres types de toxines, sous réserve de validation de la méthode.
Mikrobiologija v prehranski verigi - Horizontalna metoda za imunoencimsko ugotavljanje stafilokoknih enterotoksinov v živilih (ISO 19020:2017)
Ta standard opisuje metodo za ugotavljanje stafilokoknih enterotoksinov v mlečnih izdelkih in drugih matricah.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 19020:2017
01-september-2017
Mikrobiologija v prehranski verigi - Horizontalna metoda za imunoencimsko
ugotavljanje stafilokoknih enterotoksinov v živilih (ISO 19020:2017)
Microbiology of the food chain - Horizontal method for the immunoenzymatic detection of
staphylococcal enterotoxins in foodstuffs (ISO 19020:2017)
Mikrobiologie der Lebensmittelkette - Horizontales Verfahren für den
immunenzymatischen Nachweis von Staphylokokken-Enterotoxinen in Lebensmitteln
(ISO 19020:2017)
Microbiologie de la chaîne alimentaire - Méthode horizontale de détection des
entérotoxines staphylococciques par test immuno-enzymatique dans les aliments (ISO
19020:2017)
Ta slovenski standard je istoveten z: EN ISO 19020:2017
ICS:
07.100.30 Mikrobiologija živil Food microbiology
SIST EN ISO 19020:2017 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 19020:2017
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SIST EN ISO 19020:2017
EN ISO 19020
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2017
EUROPÄISCHE NORM
ICS 07.100.30
English Version
Microbiology of the food chain - Horizontal method for the
immunoenzymatic detection of staphylococcal
enterotoxins in foodstuffs (ISO 19020:2017)
Microbiologie de la chaîne alimentaire - Méthode Mikrobiologie der Lebensmittelkette - Horizontales
horizontale de détection des entérotoxines Verfahren für den immunenzymatischen Nachweis von
staphylococciques par test immuno-enzymatique dans Staphylokokken-Enterotoxinen in Lebensmitteln (ISO
les aliments (ISO 19020:2017) 19020:2017)
This European Standard was approved by CEN on 14 May 2017.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 19020:2017 E
worldwide for CEN national Members.
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SIST EN ISO 19020:2017
EN ISO 19020:2017 (E)
Contents Page
European foreword . 3
2
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SIST EN ISO 19020:2017
EN ISO 19020:2017 (E)
European foreword
This document (EN ISO 19020:2017) has been prepared CEN/TC 275 “Food analysis - Horizontal
methods” the secretariat of which is held by DIN, in collaboration with Technical Committee ISO/TC 34
“Food products”.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by December 2017, and conflicting national standards
shall be withdrawn at the latest by December 2017.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 19020:2017 has been approved by CEN as EN ISO 19020:2017 without any modification.
3
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SIST EN ISO 19020:2017
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SIST EN ISO 19020:2017
INTERNATIONAL ISO
STANDARD 19020
First edition
2017-06
Microbiology of the food chain —
Horizontal method for the
immunoenzymatic detection of
staphylococcal enterotoxins in
foodstuffs
Microbiologie de la chaîne alimentaire — Méthode horizontale de
détection des entérotoxines staphylococciques par test immuno-
enzymatique dans les aliments
Reference number
ISO 19020:2017(E)
©
ISO 2017
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SIST EN ISO 19020:2017
ISO 19020:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
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Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved
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SIST EN ISO 19020:2017
ISO 19020:2017(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Reagents . 2
6 Apparatus . 2
7 Sampling . 3
8 Procedure . 3
8.1 Preparation of test portion . 3
8.2 Storage of the test sample . 3
8.3 Extraction . 4
8.4 Concentration of the extract (mandatory for milk and dairy products) . 5
8.5 Recovery of the concentrated extract . 5
8.6 Storage and steps before detection . 6
8.7 Detection . 6
8.8 Performance criteria . 6
9 Quality control . 6
10 Expression of results . 7
11 Confirmation . 7
12 Performance characteristics of the method . 7
13 Test report . 9
Annex A (informative) Results of interlaboratory studies: 2013.10
Annex B (informative) Results of interlaboratory studies: 2014.15
Annex C (informative) Note on interferences .21
Bibliography .22
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SIST EN ISO 19020:2017
ISO 19020:2017(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 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by the European Committee for Standardization (CEN) Technical
Committee CEN/TC 275, Food Analysis — Horizontal methods, in collaboration with ISO Technical
Committee TC 34, Food products, Subcommittee SC 9, Microbiology, in accordance with the agreement
on technical cooperation between ISO and CEN (Vienna Agreement).
iv © ISO 2017 – All rights reserved
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SIST EN ISO 19020:2017
ISO 19020:2017(E)
Introduction
Staphylococcal enterotoxins (SEs) are proteins that can be produced in foods, by certain strains of the
coagulase positive staphylococci (CPS), mainly Staphylococcus aureus. These SEs are heat and acid stable
toxins that cause nausea, vomiting, abdominal pain and diarrhoea when ingested. Due to their stability
SEs might still be present even when coagulase positive staphylococci cannot be detected. SEs consist
of a family of more than 20 structurally-related globular monomeric proteins with molecular weights
[1]
of 19 kDa to 30 kDa. These proteins are relatively stable under changing environmental conditions,
such as heat treatment, freezing and change in pH; moreover, they are resistant to proteolytic
digestion. Typically, and depending on the sensitivity of affected individuals, nanogram (ng) amounts of
enterotoxin can cause intoxication with the symptoms described above. Due to the influence of SEs on
human health, the European Union has adopted legislation in order to increase consumer protection by
[2]
defining microbiological criteria for foodstuffs, such as CPS enumeration and detection of SEs.
Several methods have been developed for the detection and/or quantification of SEs. Some of these
methods are based on enzyme immunoassay (EIA). Other methods are based on the chemical analysis
using liquid chromatography with tandem mass spectrometry (LC-MS/MS) for the detection and
quantification of SEs. As these latter methods are currently under development, EIA methods have been
chosen as the starting point for standardization of a detection method for SEs.
The aim is to detect SEs using commercially available test kits. This document describes the protocol
for the extraction of SEs from food samples. Moreover, criteria for the performance of the kits have
been evaluated on five types of food matrices before use based on the criteria given in this document.
Response rates of different staphylococcal food poisoning outbreaks were modelled as a function of
[3]
ingested doses. For this purpose, data from the literature as well as data from the European Union
Reference Laboratory for CPS were used.
The United States Environmental Protection Agency (US EPA) benchmark dose methodology was
[4]
applied to this data set and helped to establish the benchmark dose (BMD). The BMD is defined as the
dose of a hazard (staphylococcal enterotoxin) likely to trigger health symptoms in a given percentage of
the exposed population. The BMD lower limit (BMDL) is the lower 95 % (or 90 %) confidence interval of
the BMD. This value was used to set up the acceptable value for the limit of detection 50 (LOD ) of the
50
various commercially available SE detection kits.
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SIST EN ISO 19020:2017
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SIST EN ISO 19020:2017
INTERNATIONAL STANDARD ISO 19020:2017(E)
Microbiology of the food chain — Horizontal method
for the immunoenzymatic detection of staphylococcal
enterotoxins in foodstuffs
1 Scope
This document specifies a screening method for the detection of staphylococcal enterotoxins SEA, SEB,
SECs, SED and SEE in foodstuffs. It consists of two main steps: a) extraction followed by a concentration
based on dialysis principle; and b) an immunoenzymatic detection using commercially available
detection kits.
This document is applicable to the screening of staphylococcal enterotoxins SEA to SEE in products
intended for human consumption.
Other staphylococcal enterotoxins such as types SEG, SEH, SEI, SER, SES and SET can also cause illness.
Due to the lack of commercially available detection kits, this document is applicable only to types SEA
to SEE, but may apply to other types of toxins, subject to validation of the method.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 7218, Microbiology of food and animal feeding stuffs — General requirements and guidance for
microbiological examinations
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
3.1
staphylococcal enterotoxin A, B, C, D, E
SEA, SEB, SEC, SED, SEE
exoprotein SEA, SEB, SEC, SED and SEE produced by enterotoxigenic strains of coagulase positive
staphylococci, mainly Staphylococcus aureus with a molecular weight ranging from 19 kDa to 30 kDa
3.2
specificity
SP
number of samples found to be negative divided by the total number of blank samples tested
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SIST EN ISO 19020:2017
ISO 19020:2017(E)
3.3
sensitivity
SE
number of samples found to be positive divided by the total number of samples tested at a given level of
contamination
3.4
limit of detection 50
LOD
50
concentration (ng SE/g) for which the probability of detection is 50 %
3.5
benchmark dose
BMD
dose of a hazard (e.g. staphylococcal enterotoxin) likely to trigger health symptoms in a given
percentage of the exposed population
4 Principle
This document specifies a method for the detection of staphylococcal enterotoxins (SEA to SEE) in all
foodstuffs, consisting of two main steps: a) extraction followed by a concentration based on dialysis
principle; and b) an immunoenzymatic detection using commercially available detection kits.
5 Reagents
Use only reagents of recognized analytical grade, unless otherwise specified.
5.1 Distilled or demineralized water or water of equivalent quality according to ISO 3696.
5.2 Hydrochloric acid (e.g. concentrations 5N, 1N or other dilutions).
5.3 Sodium hydroxide (e.g. concentrations 5N, 1N or other dilutions).
5.4 PBS (phosphate buffered saline), pH 7,3 ± 0,2 [NaCl/Na HPO : 145 mM/10 mM].
2 4
5.5 PEG, molecular weight 20 000 g/mol (PolyEthylene Glycol) solution.
Prepare a concentrated PEG solution: weigh 30 g of PEG powder, and add 70 ml of water (5.1).
5.6 Electrode cleaning solution (e.g. ethanol 70 %).
5.7 Immunoenzymatic detection kit dedicated to SEs. Any kit shall comply with the performance
criteria in 8.7.
6 Apparatus
Usual microbiological laboratory equipment (in accordance with ISO 7218) and, in particular, the
following.
6.1 Blender.
6.2 Balance.
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SIST EN ISO 19020:2017
ISO 19020:2017(E)
6.3 Homogenization equipment, e.g. rotary homogenizer, blender or peristaltic homogenizer.
It is highly recommended to use a rotary homogenizer, in particular for all types of food difficult to mix in
order to obtain a homogeneous sample. If a peristaltic homogenizer is used, only use bags without filter.
6.4 Shaker at room temperature, e.g. orbital shaker, magnetic stirrer, etc.
6.5 pH-meter and electrode, e.g. combination electrode.
6.6 Centrifuge, capable of operating at 3 130g minimum; if possible, capable of being refrigerated.
6.7 Dialysis membrane, molecular weight cut off (MWCO) of 6 000 Da to 8 000 Da.
6.8 Closures for dialysis membrane.
6.9 Filtering material, e.g. funnel and cotton-wool, glass-wool, etc.
6.10 Shallow tray.
6.11 Refrigerator (3 °C ± 2 °C or 5 °C ± 3 °C) and freezer (≤ −18 °C).
6.12 Laboratory ware in glass or polypropylene to avoid the adsorption of toxins (funnel, beaker,
vial, centrifuge tube, etc.).
6.13 Equipment suitable for the detection kit used, see 5.7.
6.14 Water bath (38 °C ± 2 °C).
7 Sampling
Sampling is not part of the method specified in this document.
8 Procedure
8.1 Preparation of test portion
In the case of cheese with rind, take about 10 % of rind and 90 % of core.
As enterotoxins can be heterogeneously distributed in the sample, if possible, mix and homogenize the
whole sample or a representative part of it with a blender (6.1). Use 25 g of the homogenized sample as
the test portion.
In the case of a suspected staphylococcal food poisoning outbreak (SFPO), the test sample size may be
less than 25 g. Perform the analysis as described below and adapt the steps 8.3.1 to 8.5.2 accordingly.
The ratio of the weight of the test portion and concentrated extract (8.5.2) should be approximately five
[e.g. 25 g test portion for 5,0 g to 5,5 g (maximum 5,8 g for the sticky extracts) of concentrated extract,
12,5 g test portion for 2,5 g to 2,8 g (maximum 2,9 g for the sticky extracts) of concentrated extract].
8.2 Storage of the test sample
It is recommended to store the samples at 3 °C ± 2 °C or 5 °C ± 3 °C (6.11) before analysis.
If analysis is not performed within 24 h, it is possible to freeze the samples. In this case, completely
thaw the samples at 3 °C ± 2 °C or 5 °C ± 3 °C before starting the analysis.
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SIST EN ISO 19020:2017
ISO 19020:2017(E)
To avoid loss of toxins, it is highly recommended not to freeze and thaw the samples repeatedly before
analysis.
8.3 Extraction
8.3.1 Add approximately 40 ml of water (5.1) at 38 °C ± 2 °C to the 25 g test portion, except in the case
of liquid products. For liquid products, proceed directly as described in 8.3.2. In the case of SFPO, if the
test portion is smaller than 25 g, reduce the amount of water (5.1) with the equal ratio.
Homogenize the mixture using a rotary homogenizer or a blender (6.3). This step is particularly
important in the case of high fat content products. It is recommended to use a rotary homogenizer for
all types of food samples that are difficult to mix in order to obtain a homogeneous sample.
8.3.2 Recover the entire sample and rinse the system (stem of the rotary homogenizer, the stomacher
bag or the bowl of the blender) with a minimal volume of water (5.1).
NOTE The greater the volume of liquid used the longer the length of dialysis membrane required.
8.3.3 Allow the toxins to diffuse by shaking the sample (6.4) at room temperature (18 °C to 27 °C) for
30 min to 60 min.
8.3.4 Acidify the mixture with appropriate hydrochloric acid solutions (5.2) in order to obtain a pH
between 3,5 and 4,0 measured with a pH meter (6.5).
8.3.5 Centrifuge the entire mixture at 3 130g minimum for 15 min under refrigeration temperature
(approximately 4 °C) or at room temperature (18 °C to 27 °C) (6.6).
In the case of fatty samples, a centrifugation at refrigeration temperature (approximately 4 °C) is
recommended to eliminate the fat particles before the dialysis.
8.3.6 Recover the supernatant in a beaker (6.12). If the supernatant is opaque, repeat centrifugation as
described in 8.3.5. After centrifugation pH shall be between 3,0 and 4,5.
If the pH > 4,5, proceed as described in 8.3.4.
If the pH < 3,0, the 3D structure of SEs might be damaged. Take another 25 g test portion and proceed
as described in 8.3.1.
8.3.7 Neutralize the mixture with the appropriate sodium hydroxide solutions (5.3) in order to obtain
a pH between 7,4 and 7,6.
If pH > 9,0, the 3D structure of SEs might be damaged. Take another 25 g test portion and proceed as
described in 8.3.1.
8.3.8 Centrifuge according to 8.3.5.
8.3.9 Recover the entire neutralised aqueous phase for the concentration step.
To recover the maximum amount of toxins, at the end of the acidification and neutralization steps, rinse
the electrode and beaker with some drops of water (5.1).
In the case of high fat content samples, the electrode can be cleaned using ethanol 70 % (5.6) to dissolve
fat particles after the analysis is complete.
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ISO 19020:2017(E)
8.3.10 Alternative extraction procedure (optional).
This alternative procedure may only be used in limited circumstances, such as a suspected food
poisoning event, and may not be used for milk and milk products. This alternative procedure differs
from the described procedure by omitting the dialysis concentration step.
— Take the necessary volume (depending on the kit used) of the neutralized aqueous phase obtained
in step 8.3.9 and proceed to the detection step 8.7. Store the remaining neutralized aqueous phase
at 3 °C ± 2 °C or 5 °C ± 3 °C.
— If a SEs-negative result is obtained, implement the concentration step (8.4) of the remaining
neutralized aqueous phase the same day and repeat the detection using the concentrated extract.
If this procedure is not strictly followed, a new test portion should be analysed.
8.4 Concentration of the extract (mandatory for milk and dairy products)
8.4.1 For each sample, use the PEG solution prepared according to 5.5.
8.4.2 Cut a piece of dialysis membrane (6.7) with sufficient length to contain the entire extract.
8.4.3 Soak the membrane in water (5.1) for rehydration, following the manufacturer’s instructions
(e.g. at least for 30 min at room temperature).
Before use, rinse the membrane (outside and inner parts) with water (5.1).
8.4.4 Lock one end of the membrane with a closure (6.8).
8.4.5 Fill the prepared membrane with all of the neutralized aqueous phase (8.3.9) using a funnel
and a small piece of filtering material (6.9) to filter out suspended particles. Lock the other end of the
membrane with a second closure (6.8).
8.4.6 Lay down the filled dialysis membrane in a shallow tray (6.10) filled with the PEG solution (5.5).
8.4.7 Allow the extracts to concentrate, overnight at 3 °C ± 2 °C or 5 °C ± 3 °C (6.11). If the extract is not
concentrated enough (i.e. more than 5 ml left in the dialysis membrane), lay it down in the PEG solution
for more time (up to 3 days) or add some PEG powder over the membrane.
8.5 Recovery of the concentrated extract
8.5.1 Take the dialysis membrane out of the PEG solution and rinse the outer-parts of the membrane
with water (5.1) to remove all traces of PEG solution.
8.5.2 Open one end of the membrane and recover the concentrated extract by rinsing thoroughly the
inner-part of the dialysis membrane using
— PBS (5.4) in the case of milk and dairy products, or
— water (5.1) in the case of other matrices.
Rinse thoroughly the inner-parts of the dialysis membrane to obtain a final concentrated extract mass
ranging from 5,0 g to 5,5 g (maximum 5,8 g for the sticky extracts).
Carefully transfer the concentrated extract into a glass or polypropylene vial (6.12).
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SIST EN ISO 19020:2017
ISO 19020:2017(E)
During this critical step, to recover the maximum amount of enterotoxins it is recommended
— to rub the inner-parts of the dialysis membrane (one part against another inner-part) in order to
remove and to recover the maximum of SEs, and
— to maximize the quantity of SEs recovered, carry out the recovery of the extract by repeatedly
adding small quantities of PBS (5.4) or
...
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