ISO/FDIS 629

FINAL DRAFT
International
Standard
ISO/TC 17/SC 1
Steel and cast iron — Determination
Secretariat: JISC
of manganese content —
Voting begins on:
Spectrophotometric method
2025-11-13
Aciers et fontes — Détermination de la teneur en manganèse —
Voting terminates on:
Méthode spectrophotométrique
2026-01-08
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Reference number
FINAL DRAFT
International
Standard
ISO/TC 17/SC 1
Steel and cast iron — Determination
Secretariat: JISC
of manganese content —
Voting begins on:
Spectrophotometric method
Aciers et fontes — Détermination de la teneur en manganèse —
Voting terminates on:
Méthode spectrophotométrique
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2025
IN ADDITION TO THEIR EVALUATION AS
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ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 1
6 Apparatus . 3
7 Sampling and sample preparation . 3
8 Procedure . 3
8.1 Test portion .3
8.2 Blank test .3
8.3 Determination .3
8.3.1 Preparation of test solution .3
8.3.2 Formation of coloured compound for test portion .3
8.3.3 Preparation of the compensation solution .4
8.3.4 Spectrophotometric measurement .4
8.3.5 Establishment of calibration curve .4
9 Expression of results . 6
10 Test report . 6

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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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
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This document was prepared by Technical Committee ISO/TC 17, Steel, Subcommittee SC 1, Methods of
determination of chemical composition.
This second edition cancels and replaces the first edition (ISO 629:1982), which has been technically revised.
The main changes are as follows:
— the normative references have been updated;
— Clause 3 has been added and subsequent clauses have been renumbered;
— an alternative method to prepare manganese standard solution was added;
— the blank test was added;
— the expression of results was revised.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
FINAL DRAFT International Standard ISO/FDIS 629:2025(en)
Steel and cast iron — Determination of manganese content —
Spectrophotometric method
1 Scope
This document specifies a spectrophotometric method for the determination of manganese in steel and cast iron.
The method is applicable to manganese contents between 0,001 % (mass fraction) and 4,0 % (mass fraction).
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 648, Laboratory glassware — Single-volume pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 14284, Steel and iron — Sampling and preparation of samples for the determination of chemical composition
3 Terms and definitions
No terms and definitions are listed in this document.
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/
4 Principle
Dissolution of a test portion in sulphuric-phosphoric acid mixture and nitric acid. Treatment of the test
solution with perchloric acid. Formation of the permanganate ion by sodium periodate.
Spectrophotometric measurement of the test solution at wavelength of about 545 nm.
5 Reagents
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only
grade 2 water as specified in ISO 3696 or water of equivalent purity.
Verify by blank tests that all the reagents used are free from manganese. Wherever necessary, the results
should be corrected accordingly.
5.1 Water, free from organic matter.
Bring to the boil water acidified with 10 ml/l of sulphuric acid (ρ about 1,83 g/ml), add several crystals of
sodium periodate (NaIO ) and maintain the boiling for 10 min.
5.2 Pure iron, of known low manganese less than 0,000 1 % (mass fraction).
5.3
...