SIST EN ISO 18465:2017

SLOVENSKI STANDARD
SIST EN ISO 18465:2017
01-april-2017
0LNURELRORJLMDYSUHKUDQVNLYHULJL.YDQWLWDWLYQRGRORþDQMHHPHWLþQLKWRNVLQRY
FHUHXOLGH]XSRUDER/&0606,62
Microbiology of the food chain - Quantitative determination of emetic toxin (cereulide)
using LC-MS/MS (ISO 18465:2017)
Mikrobiologie der Lebensmittelkette - Quantitative Bestimmung von emetischem Toxin
(Cereulid) mittels LC-MS/MS (ISO 18465:2017)
Microbiologie de la chaîne alimentaire - Détermination quantitative de la toxine émétique
(céreulide) par CL-SM/SM (ISO 18465:2017)
Ta slovenski standard je istoveten z: EN ISO 18465:2017
ICS:
07.100.30 Mikrobiologija živil Food microbiology
SIST EN ISO 18465:2017 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 18465:2017

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SIST EN ISO 18465:2017


EN ISO 18465
EUROPEAN STANDARD

NORME EUROPÉENNE

February 2017
EUROPÄISCHE NORM
ICS 07.100.30
English Version

Microbiology of the food chain - Quantitative
determination of emetic toxin (cereulide) using LC-MS/MS
(ISO 18465:2017)
Microbiologie de la chaîne alimentaire - Détermination Mikrobiologie der Lebensmittelkette - Quantitative
quantitative de la toxine émétique (céreulide) par CL- Bestimmung von emetischem Toxin (Cereulid) mittels
SM/SM (ISO 18465:2016) LC-MS/MS (ISO 18465:2017)
This European Standard was approved by CEN on 28 December 2016.

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 18465:2017 E
worldwide for CEN national Members.

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SIST EN ISO 18465:2017
EN ISO 18465:2017 (E)
Contents Page
European Foreword . 3

2

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SIST EN ISO 18465:2017
EN ISO 18465:2017 (E)
European Foreword
This document (EN ISO 18465:2017) has been prepared by Technical Committee 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 August 2017 and conflicting national standards shall
be withdrawn at the latest by August 2017.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] 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 18465:2017 has been approved by CEN as EN ISO 18465:2017 without any modification.
3

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SIST EN ISO 18465:2017

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SIST EN ISO 18465:2017
INTERNATIONAL ISO
STANDARD 18465
First edition
2017-01
Microbiology of the food chain —
Quantitative determination of emetic
toxin (cereulide) using LC-MS/MS
Microbiologie de la chaîne alimentaire — Détermination quantitative
de la toxine émétique (céreulide) par CL-SM/SM
Reference number
ISO 18465:2017(E)
©
ISO 2017

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SIST EN ISO 18465:2017
ISO 18465:2017(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
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
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 18465:2017
ISO 18465:2017(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General principle . 1
5 Reagents . 1
6 Apparatus and equipment . 3
7 Procedure. 4
7.1 Sample preparation . 4
7.2 Standard preparation . 4
7.3 LC-MS analysis . 5
7.3.1 LC conditions . . 5
7.3.2 MS conditions and tuning parameters . 5
7.3.3 Transitions (multiple reaction monitoring, MRM) . 6
8 Calculation . 6
9 Quality controls . 7
10 Precision . 8
10.1 General . 8
10.2 Repeatability . 8
10.3 Reproducibility . 9
Annex A (informative) Results of the interlaboratory study .10
[3]
Annex B (informative) Possible transitions of cereulide in MS .12
Bibliography .14
© ISO 2017 – All rights reserved iii

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SIST EN ISO 18465:2017
ISO 18465:2017(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 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: www . i so .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 ISO/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 18465:2017
ISO 18465:2017(E)

Introduction
Cereulide, the emetic toxin produced in foods by certain strains of Bacillus cereus, is a heat and acid
stable toxin that causes nausea and vomiting when ingested. In very rare cases, people can die after
ingestion of the toxin. Due to its stability, the toxin may still be present even when B. cereus can no
longer be detected. The presence of cereulide seems to be linked to starch-rich foods like rice (dishes)
and pasta (dishes). However, recent data suggest that the occurrence of food borne outbreaks due to
[9]
cereulide is more common to foods in general . The toxin has a cyclic structure and consists of in
total 12 monomers as a repeat of (D-O-Leucine-D-Alanine-L-O-Valine-L-Valine). Several methods
have been developed for the detection and/or quantification of the toxin. Some of these methods are
[3, 4]
nonspecific bio-assays and other methods are specifically based on the chemical analysis using
liquid chromatography with mass spectrometry (LC-MS/MS) for the detection and quantification of the
[5, 6, 7, 8]
toxin . The chemical methods are more specific for cereulide and have, therefore, been chosen as
the starting point for standardization of a method for the quantification of cereulide. Recently, research
has been done for the chemodiversity of cereulide. At least 18 cereulide variants were detected by
n
UHPLC-TOFMS and ion-trap MS sequencing, among which the previously unknown isocereulides
[10]
A–G .
© ISO 2017 – All rights reserved v

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SIST EN ISO 18465:2017

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SIST EN ISO 18465:2017
INTERNATIONAL STANDARD ISO 18465:2017(E)
Microbiology of the food chain — Quantitative
determination of emetic toxin (cereulide) using LC-MS/MS
1 Scope
This document describes the quantitative analysis of the emetic toxin cereulide using high performance
liquid chromatography (HPLC) or ultra performance liquid chromatography (UHPLC) connected to a
tandem mass spectrometer (LC-MS/MS).
This document is applicable to the analysis of the toxin in products intended for human consumption.
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 1042, Laboratory glassware — One-mark volumetric flasks
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
cereulide
toxin cyclo[D-O-Leucine-D-Alanine-L-O-Valine-L-Valine] produced by certain strains of the species of
3
B. cereus
4 General principle
13
Cereulide is extracted from the food matrix by shaking the sample with acetonitrile. C -Cereulide
6
is used as an internal standard. The components in the solution are separated using HPLC or UHPLC
and subsequently detected using tandem mass spectrometry (LC-MS/MS). For MS, the electro spray
ionization technique (ESI) is used, using the positive mode. The level of emetic toxin (cereulide) is
expressed as μg cereulide/kg product.
5 Reagents
Use only reagents of recognized analytical grade, unless otherwise specified.
5.1 Water, according to ISO 3696.
5.2 Acetonitrile, LC-MS grade.
© ISO 2017 – All rights reserved 1

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SIST EN ISO 18465:2017
ISO 18465:2017(E)

5.3 Methanol, LC-MS grade.
5.4 Formic acid, 98 % to 100 % pro analyse grade.
13 1)
5.5 Synthetic C -Cereulide.
6
1)
5.6 Synthetic Cereulide.
5.7 Ammonium formate, pro analyse grade.
5.8 Mobile phase A, consisting of 10 mmol/l ammonium formate (5.7) with 0,1 % (v/v) formic acid
(5.4) in water (5.1).
5.9 Mobile phase B, consisting of 0,1 % (v/v) formic acid (5.4) in acetonitrile (5.2).
13
5.10 C -Cereulide–stock solution IS-A, ρ = 100 000 ng/ml (in methanol).
6
13
Weigh 10 mg to the nearest 0,01 mg C -Cereulide (5.5) into a glass volumetric flask (6.11) of 100 ml
6
and dissolve, make up to the mark with methanol (5.3). This solution is not corrected for the purity of
the compound. Store the solution in the freezer (6.15).
NOTE Cereulide (labelled and non-labelled) stock and standard solutions are extremely stable, meaning
over three years when stored in a freezer (6.15)
13
5.11 C -Cereulide–standard solution IS-B, ρ = 1 000 ng/ml (in methanol).
6
13
Pipette (6.10) 1 000 μl C -Cereulide stock solution IS-A (5.10) in a glass volumetric flask (6.11)
6
of 100 ml, make up to the mark with methanol (5.3) and mix the solution. Store the solution in the
freezer (6.15).
13
5.12 C -Cereulide–standard solution IS-C, ρ = 100 ng/ml (in acetonitrile).
6
13
Pipette (6.10) 500 μl C -Cereulide stock solution IS-A (5.10) in a glass volumetric flask (6.11) of 500 ml,
6
make up to the mark with acetonitrile (5.2) and mix. Store the solution in the freezer (6.15).
13
5.13 C - Cereulide–standard solution IS-D, ρ = 10 ng/ml (in acetonitrile).
6
13
Pipette (6.10) 1 000 μl C -Cereulide standard solution IS-B (5.11) in a glass volumetric flask (6.11)
6
of 100 ml, make up to the mark with acetonitrile (5.2) and mix. Store the solution in the freezer (6.15).
5.14 Cereulide–stock solution Cer-A, ρ = 100 000 ng/ml (in methanol).
Weigh 5 mg to the nearest 0,01 mg synthetic cereulide (5.6) into a glass volumetric flask (6.11) of 50 ml
and dissolve, make up to the mark with methanol (5.3). This solution is not corrected for the purity of
the compound. Store the solution in the freezer (6.15).
5.15 Cereulide–standard solution Cer-B, ρ = 100 ng/ml (in acetonitrile).
Pipette (6.10) 500 μl cereulide stock solution A (5.14) in a glass volumetric flask (6.11) of 500 ml, make
up to the mark with acetonitrile (5.2) and mix the solution. Store the solution in the freezer (6.15).
1) Chiralix is an example of a suitable product available commercially. This information is given for the convenience
of users of this document and does not constitute an endorsement by ISO of this product.
2 © ISO 2017 – All rights reserved

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SIST EN ISO 18465:2017
ISO 18465:2017(E)

5.16 Cereulide–stock solution Cer-C, ρ = 10 ng/ml (in acetonitrile).
Pipette (6.10) 10 ml cereulide standard solution B (5.15) in a glass volumetric flask (6.11) of 100 ml,
make up to the mark with acetonitrile (5.2) and mix the solution. Store the solution in the freezer (6.15).
5.17 Positive control sample or spiked sample (level approximately 10 ng/g).
6 Apparatus and equipment
6.1 Tandem mass spectrometer, equipped with ESI interface (in positive mode) and multiple
reaction monitoring (MRM) mode.
LC system, pump system (HPLC or UHPLC), degasser, autosampler, column oven.
LC-MS software, suitable of data collection, integration.
6.2 LC column (C-18)
2)
For HPLC, Supelco Discovery® C-18, 100 mm × 2,1 mm, 5 μm or equivalent.
3)
For UHPLC, Waters BEH C-18, 100 mm or 50 mm × 2,1 mm, 1,7 μm or equivalent.
6.3 Centrifuge, capable of a centrifugal force of 1 000g to 1 500g for 50 ml tubes.
6.4 Centrifuge, capable of a centrifugal force of 10 000g to 12 000g for 2 ml tubes.
6.5 Centrifuge tubes, (plastic) with closing cap, 2 ml disposable.
6.6 Centrifuge tubes, (glass) with leakage free screw cap 50 ml.
6.7 Horizontal mechanical shaker, capable of holding 50 ml centrifuge tubes.
6.8 Analytical balance, accuracy to the nearest 0,01 mg.
6.9 Grinder, e.g. mixer, blender, cryogenic mixer.
6.10 Calibrated plunger pipettes, ranges from 10 μl to 100 μl, 100 μl to 1 000 μl, and 1 000 μl
to 5 000 μl, 2 000 μl to 10 000 μl.
6.11 Glass volumetric flasks, volume of 50 ml, 100 ml and 500 ml according to ISO 1042.
6.12 Glass autosampler vials, with snap/screw cap 2 ml.
6.13 PTFE membrane filters, diameter of 25 mm and 0,45 μm pore size.
6.14 Vortex mixer.
6.15 Freezer, capable of temperatures below −15 °C, preferably below −18 °C.
2) Supelco Discovery® is an example of a suitable product available commercially. This information is given for the
convenience of users of this document and does not constitute an endorsement by ISO of this product.
3) Waters BEH C-18 is an example of a suitable product available commercially. This information is given for the
convenience of users of this document and does not constitute an endorsement by ISO of this product.
© ISO 2017 – All rights reserved 3

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SIST EN ISO 18465:2017
ISO 18465:2017(E)

7 Procedure
7.1 Sample preparation
Store the samples (before and during the experiment) in the freezer (6.15) to prevent growth of micro-
organisms.
Take (100 ± 25) g of a representative part of the sample and transfer it to a sample jar. In case the
amount of sample is limited (for example in case of samples involved in food poisoning), take as much
sample as possible and treat identical as the other samples. In this case, a note should be mentioned
when reporting the result. Homogenize the sample by grinding (6.9).
Weigh 2,5 g, to the nearest mg (6.8), of the homogenized sample into a centrifuge tube (6.6) and
pipette (6.10) 500 μl internal standard solution IS-C (5.12); close the tube with the screw top. Mix
(6.14) about 10 s and let the tubes rest for 30 min. Glass tubes should be used especially when solutions
are stored for a longer time. For short contact times, plastic tubes can be used as well. Add 29,5 ml
acetonitrile (5.2) and close the tube again with the screw top.
Place the tube(s) horizontally on the shaker (6.7) and shake firmly for approximately 1 h. After shaking,
centrifuge the tubes for 10 min at 1 000g to 1 500g (6.3). If the solution is clear without floating
particles, no filtration step is necessary. If not, filter the liquid phase using PTFE membrane filters
(6.13), or transfer 2 ml in a centrifuge tube (6.5) and centrifuge the solution at 10 000g to 12 000g (6.4)
for 10 min.
Fill an auto sampler vial (6.12) and close the vial with a cap. The samples are now ready for analysis.
7.2 Standard preparation
The standards should be prepared directly in the vials. Pipette (6.10) the volumes as specified in
13
Table 1 with cereulide stock solution Cer-C (5.16), acetonitrile (5.2) (see NOTE) and C -cereulide
6
stock solution IS-D (5.13) into a vial (6.12) and close the vial with a cap. Mix (6.14) the solution for 20 s.
NOTE If additional clean up is needed, heptane extraction may be used to reduce the interfering (fatty)
components. After adding 29,5 ml acetonitrile, add 10,0 ml heptane and close the tubes with a screw top. Place
the tube(s) horizontally on the shaker (6.7) and shake firmly for approximately 1 h. Centrifuge the tubes for 10
min at 1 000g to 1 500g (6.3). Proceed with the sample preparation with the lower acetonitrile layer.
Table 1 — Preparation of calibration standard solutions
a
Standard Cer-C (5.16) Acetonitrile (5.2) IS-D (5.13) Cereulide std
concentration
μl μl μl ng/ml
Standard 0 0 1 000 200 0,00
Standard 1 10 990 200 0,08
Standard 2 50 950 200 0,4
Standard 3 100 900 200 0,8
Standard 4 200 800 200 1,7
Standard 5 500 500 200 4,2
Standard 6 1 000 0 200 8,3
a 13
The concentration C -Cereulide in the calibration standard solutions is 1,7 ng/ml when adding 200 μl solution IS-D
6
(5.13) to the standards (1 000 μl).
Reanalyse the sample from start when a result is outside the calibration range because of its high
concentration, weighing less of the sample <2,5 g.
If a limited amount of sample is available, use an equivalent ratio of internal standard and solutions.
13
The final concentration of C -Cereulide (IS) in the sample extract and standards is ρ = 1,7 ng/ml.
6
4 © ISO 2017 – All rights reserved

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SIST EN ISO 18465:2017
ISO 18465:2017(E)

13
The concentrations in Table 1 depend on the exact weighed amounts of cereulide Cer-A (5.14) and C -
6
Cereulide IS-A (5.10)
7.3 LC-MS analysis
7.3.1 LC conditions
Any suitable LC system can be used. Parameters, flow, retention time and gradients are instrument/type
column/manufacturer dependent and shall be determined by optimizing the LC system. Both isocratic
and gradient elution methods can be used. The parameters displayed below can be used as initial
conditions for optimization.
Injection volume: 1 μl to 20 μl
Column: C-18 HPLC or UHPLC column (6.2)
Column oven: 30 °C to 50 °C
Autosampler tray tem- 5 °C to 10 °C
perature:
Mobile phase A: 10 mmol ammonium formate (5.7) with 0,1 % (v/v) formic acid in water (5.1)
Mobile phase B: Acetonitrile (5.2) with 0,1 % (v/v) formic acid (5.4)
7.3.2 MS conditions and tuning parameters
The MS parameters can vary; they are instrument/manufacturer dependent and shall be obtained by
tuning the instrument before analysis. The parameters displayed below can be used as initial conditions
4)
® ®
for optimization; examples displayed are from a Waters Micromass Quattro Premier.
Ionization: ESI +
Capillary voltage: 3,5 kV
Cone voltage: 65 V
Extractor: 5 V
RF lens: 0 V
Source temperature: 120 °C
Desolvation temperature: 500 °C
Desolvation gas flow: 1 200 l/h
Cone gas flow: 100 l/h
LM Resolution 1: 15,0
HM Resolution 1: 15,0
Ion energy 1: 0,5
Entrance: 0
4) Waters® Micromass® is an example of a suitable product available commercially. This information is given for
the convenience of users of this document and does not constitute an endorsement by ISO of this product.
© ISO 2017 – All rights reserved 5

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SIST EN ISO 18465:2017
ISO 18465:2017(E)

Collision: 74
Exit: 1,0
LM Resolution 2: 15,0
HM Resolution 2: 15,0
Ion energy 2: 2,0
Multiplier: 650
API gas: on
Col gas: on
Mass range calibration: 50 to 1 300 m/z
7.3.3 Transitions (multiple reaction monitoring, MRM)
The transitions mentioned can deviate depending on the mass spectrometer. They are recommended
but other transitions can also be used. A list of possible transitions is available in Annex B.
+
Table 2 — Cereulide quantification MRM (M+NH ) : 1 170,7 Precursor ion
4
Cone voltage Dwell Collision energy
V s eV
First product ion trace 1 170,7 > 314,4
65 0,3 74
Quantification ion (most abundant transition)
Second product ion trace 1 170,7 > 499,4
65 0,3 56
Qualification ion (second most abundant transition)
13 +
Table 3 — C -Cereulide quantification MRM (M+NH ) : 1 176,7 Precursor ion
6 4
Cone voltage Dwell Collision energy
V s eV
First product ion trace 1 176,7 > 172,2
65 0,3 90
Internal standard quantification ion (most abundant
transition)
Second product ion trace 1 176,7 > 315,4
65 0,3 74
Qualification ion (second most abundant transition)
8 Calculation
A calibration line is made from the results from the cereulide standards as specified in Table 1 (calibration
range). The calibration line shall be forced through the origin. The calculation method shall be set as an
internal standard method, and allows quantification of the samples which are within the range.
6 © ISO 2017 – All rights reserved

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SIST EN ISO 18465:2017
ISO 18465:2017(E)

Concentration cereulide (ng/ml) is calculated with the integration software; a response factor X should
be used because of the internal standard method. X is calculated with the formula of the calibration
line, as given in Formula (1):
AreaCereulideC× onc. IS
response factor X= (1)
Area IS×Conc.Cereulide
The cereulide level in the sample can be calculated using Formula (2):
X ×Volume ml
()
cereulideconc. sample μgkg = (2)
()
Weight sample g
()
The ion ratio in standards and samples should be calculated using Formula (3):
Abundancedaughter2(Qualifier ion)
ratio % = (3)
()
Abundancedaughterr1(Qualifier ion)
Limit of detection (LOD): The calculated concentration in the solution (or the concentration recalculated
back to the original sample) wh
...