ISO/TS 9941:2005

Milk and canned evaporated milk — Determination of tin content — Spectrometric method

ISO/TS 9941|IDF/RM 160:2005 specifies a spectrometric method for the determination of the tin content in canned evaporated milk. The limit of determination of the method is 5 mg/kg.

Lait et lait concentré non sucré en boîte — Détermination de la teneur en étain — Méthode spectrométrique

General Information

• Status: Published
• Publication Date: 18-Jul-2005
• ICS: 67.100.10 - Milk and processed milk products
• Technical Committee: ISO/TC 34/SC 5 - Milk and milk products
• Drafting Committee: ISO/TC 34/SC 5 - Milk and milk products
• Current Stage: 9093 - International Standard confirmed
• Start Date: 19-Apr-2024
• Completion Date: 14-Feb-2026

Relations

• Revises: ISO/TS 9941:2003 - Milk and canned evaporated milk — Determination of tin content — Spectrometric method
• Effective Date: 15-Apr-2008

Overview

ISO/TS 9941:2005 is an essential technical specification developed by the International Organization for Standardization (ISO) and the International Dairy Federation (IDF). It outlines a precise spectrometric method for determining the tin content in canned evaporated milk products. This method offers a reliable and standardized procedure specifically designed to detect tin concentrations at or above 5 mg/kg within milk samples. As tin contamination can pose health risks and affect product quality, this standard plays a critical role in ensuring food safety and regulatory compliance within the dairy industry.

Key Topics

• Scope and Purpose
  The specification applies strictly to canned evaporated milk, detailing a robust method to quantify tin, an element that can leach from packaging materials or processing equipment.

• Principle of the Method
  The test involves mineralizing the organic milk material with nitric and sulfuric acids, followed by complexation of tin using quercetin. The final absorbance is measured at 437 nm via spectrometry, enabling quantification of tin in the sample.

• Limit of Determination
  The method detects tin at concentrations as low as 5 mg per kilogram of evaporated milk.

• Reagents and Apparatus
  The procedure specifies the use of pure, tin-free reagents, such as nitric acid, sulfuric acid, quercetin, and specialized standard tin solutions, alongside precise laboratory instruments including calibrated mineralization flasks and a spectrometer with 10 mm path length cells.

• Sample Preparation and Testing
  Samples must be carefully prepared to prevent contamination, heated in controlled water baths, and mineralized before spectrometric analysis. The method includes detailed steps to ensure accuracy, such as masking interfering ions and verifying tin recovery.

• Calculation and Reporting
  The tin concentration is calculated and reported as milligrams of tin per kilogram of evaporated milk, ensuring consistent and clear communication of results.

Applications

• Quality Control in Dairy Production
  Dairy manufacturers utilize this method for routine testing of evaporated milk products to ensure compliance with food safety standards and packaging regulations.

• Regulatory Compliance
  Food safety authorities may reference ISO/TS 9941:2005 to verify tin levels and assess potential risks from metal contamination in canned milk products.

• Research and Development
  Laboratories engaged in product development can employ this spectrometric method to monitor tin exposure during processing and packaging improvements.

• Packaging Material Testing
  The standard aids in evaluating tin leaching from cans and other packaging, facilitating safer material selection by packaging engineers.

Related Standards

• ISO 3696:1987 – Specifies the quality of water for analytical laboratory use, which ISO/TS 9941 references for reagent preparation.

• ISO 707 / IDF 50 – Provides guidelines on sampling milk and milk products, essential to ensure representative test samples for accurate tin determination.

• ISO/TS 9940 – Covers related analytical methods for detecting minor components in milk and milk products.

• ISO Standards on Food Safety and Metal Contamination – Various ISO standards address limits and analysis of heavy metals in food items, which complement requirements for tin testing.

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This specification is critical for maintaining the safety, integrity, and quality of evaporated milk by providing a scientifically validated and repeatable method for tin content analysis. Its adherence supports consumer protection and facilitates international trade compliance within the dairy sector.

Standards Content (Sample)

TECHNICAL ISO/TS
SPECIFICATION 9941
IDF/RM
Second edition
2005-06-15
Milk and canned evaporated milk —
Determination of tin content —
Spectrometric method
Lait et lait concentré non sucré en boîte — Détermination de la teneur
en étain — Méthode spectrométrique

Reference numbers
IDF/RM 160:2005(E)
©
ISO and IDF 2005
IDF/RM 160:2005(E)
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©  ISO and IDF 2005
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ii © ISO and IDF 2005 – All rights reserved

IDF/RM 160:2005(E)
Contents Page
Foreword. iv
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Principle. 1
5 Reagents. 1
6 Apparatus . 2
7 Sampling. 3
8 Preparation of test sample. 3
9 Procedure . 3
9.1 Test portion and pretreatment. 3
9.2 Mineralization. 3
9.3 Colour development . 4
9.4 Blank test. 4
9.5 Preparation of the calibration graph. 4
9.6 Check on tin losses . 5
9.7 Spectrometric measurements . 5
9.8 Number of determinations . 5
10 Calculation and expression of results. 5
10.1 Calculation. 5
10.2 Expression of results . 5
11 Test report . 5
Bibliography . 6

IDF/RM 160:2005(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. 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.
In other circumstances, particularly when there is an urgent market requirement for such documents, a
technical committee may decide to publish other types of normative document:
— an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in
an ISO working group and is accepted for publication if it is approved by more than 50 % of the members
of the parent committee casting a vote;
— an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical
committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting
a vote.
An ISO/PAS or ISO/TS is reviewed after three years in order to decide whether it will be confirmed for a
further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or ISO/TS is
confirmed, it is reviewed again after a further three years, at which time it must either be transformed into an
International Standard or be withdrawn.
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.
ISO/TS 9941IDF/RM 160 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee
SC 5, Milk and milk products, and the International Dairy Federation (IDF). It is being published jointly by ISO
and IDF.
This second edition cancels and replaces the first edition (ISO/TS 9941IDF/RM 160:2003), which has been
technically revised.
iv © ISO and IDF 2005 – All rights reserved

IDF/RM 160:2005(E)
Foreword
IDF (the International Dairy Federation) is a worldwide federation of the dairy sector with a National
Committee in every member country. Every National Committee has the right to be represented on the IDF
Standing Committees carrying out the technical work. IDF collaborates with ISO and AOAC International in
the development of standard methods of analysis and sampling for milk and milk products.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the Action Teams and Standing Committees are circulated to the National Committees for voting.
Publication as an International Standard requires approval by at least 50 % of IDF National Committees
casting a vote.
In other circumstances, particularly when there is an urgent market requirement for such documents, a
Standing Committee may decide to publish an other type of normative document which is called by IDF:
Reviewed method. Such a method represents an agreement between the members of a Standing Committee
and is accepted for publication if it is approved by at least 50 % of the committee members casting a vote.
A Reviewed method is equal to an ISO/PAS or ISO/TS and will, therefore, also be published jointly under ISO
conditions.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. IDF shall not be held responsible for identifying any or all such patent rights.
ISO/TS 9941IDF/RM 160 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee
SC 5, Milk and milk products, and the International Dairy Federation (IDF). It is being published jointly by ISO
and IDF.
All work was carried out by the Joint ISO/IDF Action Team on Minor compounds, of the Standing Committee
on Minor components and characterization of physical properties, under the aegis of its project leaders, Dr M.
Carl (DE) and Dr G. Ellen (NL).
This second edition cancels and replaces the first edition (ISO/TS 9941IDF/RM 160:2003), which has been
technically revised.
IDF/RM 160:2005(E)
Introduction
This Technical Specification (Reviewed Method for IDF) specifies a spectrometric method for the
determination of tin content in canned evaporated milk. Its limit of determination is 5 mg of tin per kilogram.
Despite several attempts, the Joint IDF-ISO Action Team (JAT) on Minor compounds could not organize a
collaborative study with a sufficient number of participating laboratories to be in accordance with ISO 5725-2.
Thus no precision figures for repeatability and reproducibility could be established. However, the method has
been proven to be reliable by at least three experienced laboratories and particularly with respect to its
accuracy.
The method was therefore adopted as a Technical Specification rather than as an International Standard.
vi © ISO and IDF 2005 – All rights reserved

TECHNICAL SPECIFICATION
IDF/RM 160:2005(E)
Milk and canned evaporated milk — Determination of tin
content — Spectrometric method
1 Scope
This Technical Specification (Reviewed Method for IDF) specifies a spectrometric method for the
determination of the tin content in canned evaporated milk. The limit of determination of the method is 5 mg/kg.
2 Normative references
The following referenced documents are indispensable for the application 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 3696:1987, 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.
3.1
tin content
mass fraction of substances determined by the procedure specified in this Technical Specification
NOTE The tin content is expressed in milligrams per kilogram of sample.
4 Principle
The organic material is mineralized with a mixture of nitric
...