ISO 23822:2026

• Abstract:

  This document specifies a liquid chromatography tandem mass spectrometry method (LC-MS/MS) for the determination of nitroimidazole residues in eggs and egg products. This document is applicable to eggs and egg products, including whole eggs (fresh, frozen or pasteurized), egg yolk (liquid, frozen, dried or pasteurized), egg white (liquid, frozen, dried or pasteurized), whole egg powder, egg white powder, egg yolk powder, and liquid or dried albumin preparations.

• Status: Published
• Publication Date: 29-Jun-2026
• ICS: 67.120.20 - Poultry and eggs
• Technical Committee: ISO/TC 34/SC 6 - Meat, poultry, fish, eggs and their products
• Drafting Committee: ISO/TC 34/SC 6 - Meat, poultry, fish, eggs and their products
• Current Stage: 6060 - International Standard published
• Start Date: 30-Jun-2026
• Due Date: 28-Nov-2026
• Completion Date: 30-Jun-2026

ISO 23822:2026 is an International Standard published by ISO for testing eggs and egg products. It specifies a liquid chromatography-tandem mass spectrometry method (LC-MS/MS) for determining nitroimidazole residues in egg matrices, for use by testing laboratories, quality teams, and food-control users who need a structured analytical procedure.

What does ISO 23822:2026 specify?

ISO 23822:2026 specifies an LC-MS/MS method for nitroimidazole residues in eggs and egg products, including whole eggs, egg yolk, egg white, whole egg powder, egg white powder, egg yolk powder, and liquid or dried albumin preparations. The method covers the analytical steps from sample preparation through confirmation, quantification, and reporting.

ISO 23822:2026 does not treat sampling as part of the method itself. Clause 5 points readers to a recommended sampling method in CAC/GL 50-2004 and stresses that the laboratory needs a representative sample that stays stable in transport and storage.

The document is organized into these main clauses and annexes:

Part	What it covers
Clause 1	Scope
Clause 2	Normative references
Clause 3	Terms and definitions
Clause 4	Principle
Clause 5	Sampling
Clause 6	Preparation of test sample
Clause 7	Reagents and materials
Clause 8	Apparatus
Clause 9	Procedure
Clause 10	Test report
Annex A	Compound data for the nitroimidazoles
Annex B	LC-MS/MS chromatograms for the quantification ion pairs
Annex C	Collaborative interlaboratory test results

What are the key requirements of ISO 23822:2026?

Sample handling and preparation

• Clause 5 expects a representative sample of at least 1 kg, kept free from deterioration and change during transport or storage. In practice, this matters because residue results are only meaningful if the lab receives material that still represents the batch.
• Clause 6 gives different preparation paths for fresh shell-on eggs and for other egg products. Fresh eggs are shelled and homogenized, while other products are homogenized directly; dried or concentrated products are reconstituted with water before analysis.
• Clause 6.2 requires storage of the test sample and standby sample between -20 °C and -16 °C. That helps preserve residues until the analysis is complete.

Extraction, cleanup and LC-MS/MS analysis

• Clause 4 sets the principle: extract with acetonitrile, purify by solid-phase extraction, then determine and confirm the residues by LC-MS/MS using an internal standard method. The internal standard approach is important because it corrects for losses and instrument variation.
• Clause 7 specifies analytical-grade reagents and the named solvents and solutions used to prepare extracts, standards and mobile phases, including water in accordance with ISO 3696. This matters because residue analysis is sensitive to contamination and matrix effects.
• Clause 8 and Clause 9.2 to 9.3 describe the workflow: weigh 5 g of prepared sample, add isotope internal standard, extract with acetonitrile, salt out with sodium chloride, use n-hexane, clean up on Oasis PRiME HLB or an equivalent cartridge, evaporate, reconstitute, and filter through a 0.22 μm nylon filter. In practice, this is the part that makes the egg matrix suitable for LC-MS/MS measurement.

Identification, quantification and reporting

• Clause 9.4 specifies the LC-MS/MS conditions, including methanol and 0.1 % aqueous formic acid as the mobile phases, a defined gradient, electrospray ionization in positive mode, and multiple reaction monitoring (MRM). The MRM ion pairs in Table 2 are the basis for targeted detection of the listed analytes and their deuterated internal standards.
• Clause 9.5 requires confirmation by both retention time and ion abundance ratios. The retention time of a sample peak has to match the standard closely, and the ion ratio has to fall within the tolerances in Table 3. That means a signal is not enough on its own - identity must also fit the chromatographic and ion ratio checks.
• Clause 9.6 quantifies by calibration curve, using the ratio of analyte peak area to deuterated internal standard peak area. If the response is outside the linear range, the sample must be diluted and reanalyzed.
• Clause 9.7 requires a blank test, and Clause 9.8 gives the calculation of residue content from the measured concentrations, extraction volumes, final volume, and sample mass. Clause 9.8 also says to report the arithmetic average of the two single test results when repeatability conditions are used.
• Clauses 9.9 to 9.11 set performance expectations: the limit of detection is 0.4 μg/kg for the listed nitroimidazoles, the limit of quantification is 1.0 μg/kg, and the coefficient of variation shall be below 20 %. Clause 9.11 also links the method to a collaborative interlaboratory study in Annex C.
• Clause 10 defines what the test report has to contain: sample identification, the sampling method if known, the method reference to ISO 23822, the results with the calculation clause, any deviations, and the test date. This is the part that supports traceability in routine work and audits.

What terms does ISO 23822:2026 define?

• Nitroimidazole residues - In Clause 3.1, this means the target compounds covered by the method, including metronidazole, dimetridazole, ronidazole, ipronidazole, hydroxymetronidazole, hydroxydimetridazole and hydroxyipronidazole.
• Liquid chromatography-tandem mass spectrometry (LC-MS/MS) - The separation and detection technique used in the standard to identify and measure the residues in egg matrices.
• High performance liquid chromatography (HPLC) - The liquid chromatography part of the LC-MS/MS system used for separation before mass spectrometric detection.
• Multiple reaction monitoring (MRM) - The MS mode used in Clause 9.4 to monitor selected ion transitions for each analyte and internal standard.
• Internal standard method - The quantification approach used in Clause 4 and Clause 9.6, where deuterated analogues are added to correct for extraction and instrument variation.
• Retention time - The time at which a compound elutes from the chromatographic column, used in Clause 9.5 for confirmation against standards.
• Ion abundance ratio - The ratio of the qualitative ion intensity to the quantitative ion intensity, used in Clause 9.5 to support identity confirmation.

Who uses ISO 23822:2026?

ISO 23822:2026 is used by analytical laboratories that test eggs and egg products for residue monitoring, regulatory control, or supplier verification. It is also relevant to food safety teams, quality managers, and contract laboratories that need a repeatable LC-MS/MS procedure for routine screening and confirmatory testing.

Egg processors and buyers may use the document when they need to specify how residue results are generated and reported. In practice, it supports method setup, calibration, matrix handling, confirmation checks, and formal reporting.

Which standards are used with ISO 23822:2026?

Standard or guideline	How it contributes
ISO 3696	Specifies grade 1 water for analytical laboratory use, which the method requires for reagent and solution preparation.
CAC/GL 50-2004	Provides the recommended sampling method referred to in Clause 5.
ISO 5725-2	Provides the basis for the collaborative interlaboratory precision study cited in Annex C.

What does the ISO 23822:2026 document contain?

ISO 23822:2026 contains a full analytical method, not just a principle statement. Clause 9 gives the practical procedure for extraction, cleanup, instrument setup, confirmation, quantification, blank testing, calculation, and performance limits.

It also contains operating detail that laboratories need to run the method consistently. That includes reagent lists, standard preparation, LC gradient conditions, MRM transitions, retention-time and ion-ratio criteria, and the reporting items for the test report.

Annex A provides compound information such as names, CAS Registry Numbers, molecular formulas, molecular masses and structural formulas. Annex B shows chromatograms for the quantification ion pairs, which helps analysts recognize the target peaks and their isotope-labelled internal standards.

Annex C summarizes a collaborative interlaboratory study across egg samples and residue levels. That annex is useful for method users who need context on repeatability, reproducibility, and the concentration ranges covered by the precision data.

International
Standard
ISO 23822
First edition
Eggs and egg products —
2026-06
Determination of nitroimidazole
residues — Liquid chromatography-
tandem mass spectrometry method
Œufs et ovoproduits — Dosage des résidus de nitroimidazole
— Méthode de chromatographie en phase liquide couplée à la
spectrométrie de masse en tandem
Reference number
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Sampling . 1
6 Preparation of test sample . 2
6.1 Preparation of sample .2
6.1.1 Fresh eggs and egg products with shell.2
6.1.2 Other egg products .2
6.2 Storage .2
7 Reagents and materials . 2
7.1 Reagents .2
7.2 Preparation of solution .2
7.3 Standards .3
7.4 Preparation of standard solution . .3
7.5 Materials .4
8 Apparatus . 4
9 Procedure . 4
9.1 General .4
9.2 Extraction .4
9.3 Purification .4
9.4 LC-MS/MS analysis .4
9.4.1 HPLC conditions .4
9.4.2 MS parameters .5
9.5 Confirmation .6
9.5.1 Retention time .6
9.5.2 Ion abundance ratios .6
9.6 Quantification . . .6
9.7 Blank test .6
9.8 Calculation .7
9.9 Limits of detection .7
9.10 Limits of quantification .7
9.11 Precision . . .7
10 Test report . 7 ®
Annex A (informative) Compound name, CAS Registry Number , molecular formula, relative
molecular mass and structural formula . 8
Annex B (informative) LC-MS/MS chromatograms of the quantification ion pairs for
nitroimidazoles from the mixed standard solution . 9
Annex C (informative) Collaborative interlaboratory test result .16
Bibliography . 17

iii
Foreword
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iv
International Standard ISO 23822:2026(en)
Eggs and egg products — Determination of nitroimidazole
residues — Liquid chromatography-tandem mass
spectrometry method
1 Scope
This document specifies a liquid chromatography tandem mass spectrometry method (LC-MS/MS) for the
determination of nitroimidazole residues in eggs and egg products.
This document is applicable to eggs and egg products, including whole eggs (fresh, frozen or pasteurized),
egg yolk (liquid, frozen, dried or pasteurized), egg white (liquid, frozen, dried or pasteurized), whole egg
powder, egg white powder, egg yolk powder, and liquid or dried albumin preparations.
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
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
nitroimidazole residues
compounds including metronidazole, dimetridazole, ronidazole, ipronidazole, hydroxymetronidazole,
hydroxydimetridazole and hydroxyipronidazole
4 Principle
The test sample is extracted using acetonitrile. The extracted solution is purified through solid-phase
extraction. The nitroimidazole residues are determined and confirmed by LC-MS/MS, and quantified with
an internal standard method.
5 Sampling
Sampling is not part of the method specified in this document. A recommended sampling method is given in
CAC/GL 50-2004.
It is essential that the laboratory receives a sample which is truly representative and remains unaffected by
damage or change during transport or storage.
Start from a representative sample of at least 1 kg.

Store the sample in such a way that deterioration and change in composition are prevented.
6 Preparation of test sample
6.1 Preparation of sample
6.1.1 Fresh eggs and egg products with shell
Take 16 (about 1 kg) fresh eggs or egg products and remove the shells. Homogenize the egg contents sample
with the appropriate equipment. Transfer the homogenized sample into a polyethylene bottle.
6.1.2 Other egg products
Homogenize the egg products samples thoroughly. Transfer the homogenized sample into a polyethylene
bottle.
For concentrated or dried egg products, weigh 5 g (to the nearest 0,01 g) of the homogenized sample into a
50 ml centrifuge tube, add 20 ml of water for reconstitution, vortex for 10 min, and then sonicate for 10 min.
Ensure that the sample is evenly dispersed to obtain the reconstituted egg solutions.
NOTE This step is necessary to reconstitute dried (e.g. egg powder) or concentrated egg products to their ready-
to-use form by diluting them to the required concentration. Liquid and frozen products are already in a suitable state
for analysis and can bypass this procedure.
6.2 Storage
Store the test sample and standby sample at a temperature between −20 °C and −16 °C.
7 Reagents and materials
Reagents shall be of recognized analytical grade, unless otherwise specified.
7.1 Reagents
7.1.1 Water, grade 1 in accordance with ISO 3696.
7.1.2 Acetonitrile (CH CN), HPLC grade.
7.1.3 Methanol (CH OH), HPLC grade.
7.1.4 Formic acid (HCOOH), HPLC grade.
7.1.5 Sodium chloride (NaCl).
7.1.6 Dimethyl sulfoxide (DMSO).
7.1.7 n-Hexane (C H ).
6 14
7.2 Preparation of solution
7.2.1 10 % Methanol aqueous solution (containing 0,1 % formic acid).
Pipette 10 ml of methanol and 0,1 ml of formic acid into a 100 ml one-mark volumetric flask. Dilute to the
mark with water and mix.
...