SIST EN ISO 21587-2:2008

Chemical analysis of aluminosilicate refractory products (alternative to the X-ray fluorescence method) - Part 2: Wet chemical analysis (ISO 21587-2:2007)

This part of ISO 21587 specifies traditional ("wet") methods for the chemical analysis of aluminosilicate refractory products and raw materials. The methods are applicable to the determination of the following: silicon(IV) oxide (SiO2) aluminium oxide (Al2O3) iron(III) oxide (total iron oxide calculated as Fe2O3) titanium(IV) oxide (TiO2) manganese(II) oxide (MnO) calcium oxide (CaO) magnesium oxide (MgO) sodium oxide (Na2O) potassium oxide (K2O) chromium(III) oxide (Cr2O3) zirconium oxide (ZrO2) phosphorous(V) oxide (P2O5) This part of ISO 21587 gives alternatives to the X-ray fluorescence (XRF) method given in ISO 12677:2003, Chemical analysis of refractory products by XRF - Fused cast bead method.

Chemische Analyse feuerfester Erzeugnisse aus Alumosilicat (Alternative zum Röntgenfluoreszenzverfahren) - Teil 2: Nasschemische Analyse (ISO 21587-2:2007)

Dieser Teil von ISO 21587 legt die traditionellen nasschemischen Verfahren für die chemische Analyse von feuerfesten Erzeugnissen und Rohstoffen aus Alumosilicat fest.
Die Verfahren gelten für die folgenden Bestimmungen:
   Silicium(IV) oxid (SiO2);
   Aluminiumoxid (Al2O3);
   Eisen(III) oxid (Gesamteisengehalt, berechnet als Fe2O3);
   Titan(IV) oxid (TiO2);
   Mangan(II) oxid (MnO);
   Calciumoxid (CaO);
   Magnesiumoxid (MgO);
   Natriumoxid (Na2O);
   Kaliumoxid (K2O);
   Chrom(III) oxid (Cr2O3);
   Zirkoniumoxid (ZrO2);
   Phosphor(V) oxid (P2O5).
Dieser Teil von ISO 21587 gibt Alternativen zur Röntgenfluoreszenzanalyse (RFA), die in ISO 12677:2003, Chemische Analyse von feuerfesten Erzeugnissen durch RFA — Schmelzaufschluss Verfahren, festgelegt ist.

Analyse chimique des produits réfractaires d'aluminosilicates (méthode alternative a la méthode par fluorescence de rayons X) - Partie 2: Méthodes d'analyse chimique par voie humide (ISO 21587-2:2007)

L'ISO 21587-2:2007 spécifie des méthodes traditionnelles («humides») d'analyse chimique des produits et matières premières réfractaires d'aluminosilicates.
Les méthodes s'appliquent au dosage des éléments suivants:
l'oxyde de silicium(IV) (SiO2)l'oxyde d'aluminium (Al2O3)l'oxyde de fer(III) (oxyde de fer total calculé en tant que Fe2O3)l'oxyde de titane(IV) (TiO2)l'oxyde de manganèse(II) (MnO)l'oxyde de calcium (CaO)l'oxyde de magnésium (MgO)l'oxyde de sodium (Na2O)l'oxyde de potassium (K2O)l'oxyde de chrome(III) (Cr2O3)l'oxyde de zirconium (ZrO2)l'oxyde de phosphore(V) (P2O5)
La présente partie de l'ISO 21587 fournit une méthode alternative à la méthode par fluorescence de rayons X (FRX) donnée dans l'ISO 12677:2003.

Kemijska analiza alumosilikatnih ognjevzdržnih izdelkov (alternativa rentgenski fluorescenčni metodi) - 2. del: Mokra kemijska analiza (ISO 21587-2:2007)

General Information

• Status: Published
• Publication Date: 17-Feb-2008
• ICS: 81.080 - Refractories
• Technical Committee: IKER - Ceramics
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 15-Oct-2007
• Due Date: 20-Dec-2007
• Completion Date: 18-Feb-2008
• Ref Project: EN ISO 21587-2:2007 - Chemical analysis of aluminosilicate refractory products (alternative to the X-ray fluorescence method) - Part 2: Wet chemical analysis (ISO 21587-2:2007)

Relations

• Replaces: SIST EN 955-2:1998 - Chemical analysis of refractory products - Part 2: Products containing silica and/or alumina (wet method)
• Effective Date: 01-Mar-2008

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 21587-2:2008
01-marec-2008
1DGRPHãþD
SIST EN 955-2:1998
.HPLMVNDDQDOL]DDOXPRVLOLNDWQLKRJQMHY]GUåQLKL]GHONRYDOWHUQDWLYDUHQWJHQVNL
IOXRUHVFHQþQLPHWRGLGHO0RNUDNHPLMVNDDQDOL]D,62
Chemical analysis of aluminosilicate refractory products (alternative to the X-ray
fluorescence method) - Part 2: Wet chemical analysis (ISO 21587-2:2007)
Chemische Analyse feuerfester Erzeugnisse aus Alumosilicat (Alternative zum
Röntgenfluoreszenzverfahren) - Teil 2: Nasschemische Analyse (ISO 21587-2:2007)
Analyse chimique des produits réfractaires d'aluminosilicates (méthode alternative a la
méthode par fluorescence de rayons X) - Partie 2: Méthodes d'analyse chimique par voie
humide (ISO 21587-2:2007)
Ta slovenski standard je istoveten z: EN ISO 21587-2:2007
ICS:
81.080
SIST EN ISO 21587-2:2008 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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EUROPEAN STANDARD
EN ISO 21587-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2007
ICS 81.080 Supersedes EN 955-2:1995
English Version
Chemical analysis of aluminosilicate refractory products
(alternative to the X-ray fluorescence method) - Part 2: Wet
chemical analysis (ISO 21587-2:2007)
Analyse chimique des produits réfractaires Chemische Analyse feuerfester Erzeugnisse aus
d'aluminosilicates (méthode alternative à la méthode par Alumosilicat (Alternative zum
fluorescence de rayons X) - Partie 2: Méthodes d'analyse Röntgenfluoreszenzverfahren) - Teil 2: Nasschemische
chimique par voie humide (ISO 21587-2:2007) Analyse (ISO 21587-2:2007)
This European Standard was approved by CEN on 13 September 2007.
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 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 Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 21587-2:2007: E
worldwide for CEN national Members.

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EN ISO 21587-2:2007 (E)






Foreword



The text of ISO 21587-2:2007 has been prepared by Technical Committee ISO/TC 33
"Refractories” of the International Organization for Standardization (ISO) and has been taken
over as EN ISO 21587-2:2007 by Technical Committee CEN/TC 187 "Refractory products and
materials", the secretariat of which is held by BSI.

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 March 2008, and conflicting national
standards shall be withdrawn at the latest by March 2008.

This document supersedes EN 955-2:1995.

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, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United
Kingdom.



Endorsement notice

The text of ISO 21587-2:2007 has been approved by CEN as EN ISO 21587-2:2007 without any
modifications.

2

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INTERNATIONAL ISO
STANDARD 21587-2
First edition
2007-03-01

Chemical analysis of aluminosilicate
refractory products (alternative to the
X-ray fluorescence method) —
Part 2:
Wet chemical analysis
Analyse chimique des produits réfractaires d'aluminosilicates (méthode
alternative à la méthode par fluorescence de rayons X) —
Partie 2: Méthodes d'analyse chimique par voie humide





Reference number
ISO 21587-2:2007(E)
©
ISO 2007

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ISO 21587-2:2007(E)
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ii © ISO 2007 – All rights reserved

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ISO 21587-2:2007(E)
Contents Page
Foreword. iv
1 Scope . 1
2 Normative references . 1
3 Determination of residual silicon(IV) oxide in solution . 2
4 Determination of aluminium oxide. 3
5 Determination of iron(III) oxide. 5
6 Determination of titanium(IV) oxide . 7
7 Determination of manganese(II) oxide by permanganate absorption spectrophotometric
method . 9
8 Determination of calcium oxide . 10
9 Determination of magnesium oxide. 11
10 Determination of sodium oxide by flame photometry . 12
11 Determination of potassium oxide by flame photometry . 14
12 Determination of chromium(III) oxide using diphenylcarbazide. 14
13 Determination of zirconium oxide by Xylenol orange. 16
14 Determination of phosphorus(V) oxide by molybdenum blue. 17
15 Test report . 19

© ISO 2007 – All rights reserved iii

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ISO 21587-2:2007(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.
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 21587-2 was prepared by Technical Committee ISO/TC 33, Refractories.
ISO 21587 consists of the following parts, under the general title Chemical analysis of aluminosilicate
refractory products (alternative to the X-ray fluorescence method):
⎯ Part 1: Apparatus, reagents, dissolution and gravimetric silica
⎯ Part 2: Wet chemical analysis
⎯ Part 3: Inductively coupled plasma and atomic absorption spectrometry methods

iv © ISO 2007 – All rights reserved

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INTERNATIONAL STANDARD ISO 21587-2:2007(E)

Chemical analysis of aluminosilicate refractory products
(alternative to the X-ray fluorescence method) —
Part 2:
Wet chemical analysis
1 Scope
This part of ISO 21587 specifies traditional ("wet") methods for the chemical analysis of aluminosilicate
refractory products and raw materials.
The methods are applicable to the determination of the following:
⎯ silicon(IV) oxide (SiO )
2
⎯ aluminium oxide (Al O )
2 3
⎯ iron(III) oxide (total iron oxide calculated as Fe O )
2 3
⎯ titanium(IV) oxide (TiO )
2
⎯ manganese(II) oxide (MnO)
⎯ calcium oxide (CaO)
⎯ magnesium oxide (MgO)
⎯ sodium oxide (Na O)
2
⎯ potassium oxide (K O)
2
⎯ chromium(III) oxide (Cr O )
2 3
⎯ zirconium oxide (ZrO )
2
⎯ phosphorous(V) oxide (P O )
2 5
This part of ISO 21587 gives alternatives to the X-ray fluorescence (XRF) method given in ISO 12677:2003,
Chemical analysis of refractory products by XRF — Fused cast bead method.
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 21587-1:2007, Chemical analysis of aluminosilicate refractory products (alternative to the X-ray
fluorescence method) — Part 1: Apparatus, reagents, dissolution and gravimetric silica
ISO 26845, Chemical analysis of refractories — General requirements for wet chemical analysis, atomic
absorption spectrometry and inductively coupled plasma methods
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ISO 21587-2:2007(E)
3 Determination of residual silicon(IV) oxide in solution
3.1 Principle
An aliquot portion of the stock solution (S1) or (S′1), after pH adjustment, is treated with ammonium
molybdate and the silicomolybdate is reduced to yield molybdenum blue, the absorbance of which is
measured.
The sum of this residual silicon(IV) oxide in solution plus the mass of silicon(IV) oxide (m − m ) derived in
1 2
ISO 21587-1:2007, 4.2.2.3 or 4.2.3.3, gives the total silicon(IV) oxide content.
3.2 Procedure
This determination should be commenced with little delay after the stock solution (S1) or (S′1) is prepared, as
prolonged standing can allow polymerization of silica to occur, leading to low results.
Transfer 10 ml of stock solution (S1) or (S′1) obtained in 4.2.2.3 or 4.2.3.3 of ISO 21587-1:2007 to a 100 ml
plastic beaker, and add 2 ml of hydrofluoric acid (1+9), mix with a plastic rod and allow to stand for 10 min.
Then add 50 ml of boric acid solution. Add 2 ml of ammonium molybdate solution while mixing at a
temperature of 25 °C, and allow to stand for 10 min. Add 5 ml of L(+)-tartaric acid solution while stirring, and
after 1 min add to it 2 ml of L(+)-ascorbic acid solution. Transfer the solution to a 100 ml volumetric flask, dilute
to the mark with water, mix, and allow to stand for 60 min.
Measure the absorbance of the solution in a 10 mm cell at a wavelength of 650 nm using water as the
reference.
3.3 Plotting the calibration graph
Transfer 0, 2, 4, 6, 8 and 10 ml aliquot portions (0 mg to 0,4 mg as silicon(IV) oxide) of dilute standard
silicon(IV) oxide solution (SiO 0,04 mg/ml) into several 100 ml plastic beakers, and to each add 10 ml of
2
blank solution (B1) or (B′1) obtained in 4.2.2.4 or 4.2.3.4 of ISO 21587-1:2007. Treat these solutions and
measure the absorbance as given in 3.2, and plot the absorbances against the amounts of silicon(IV) oxide.
Prepare the calibration graph by adjusting the curve so that it passes through the point of origin.
3.4 Calculation
Calculate the mass fraction of silicon(IV) oxide, w , as a percentage, using the following equation, with the
SiO
2
absorbances obtained by the procedure in 3.2 and the plotting of the calibration graph by the procedure in 3.3.
500
mm−+m−m×
()()
12 3 4
10
(1)
w=×100
SiO
2
m
where
m is the mass, in g, from 4.2.2.3 or 4.2.3.3 of ISO 21587-1:2007;
1
m is the mass, in g, from 4.2.2.3 or 4.2.3.3 of ISO 21587-1:2007;
2
m is the mass, in g, of silicon(IV) oxide in the aliquot portion of stock solution (S1) or (S′1) as
3
applicable;
m is the mass, in g, of silicon(IV) oxide in the aliquot portion of blank solution (B1) or (B′1) as
4
applicable;
m is the mass, in g, of the test portion from 4.2.2.2 or 4.2.3.2 of ISO 21587-1:2007.
2 © ISO 2007 – All rights reserved

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ISO 21587-2:2007(E)
4 Determination of aluminium oxide
4.1 General
The determination of titanium(IV) oxide is carried out using one of the following methods:
a) separation by cupferron-CyDTA-zinc back titration method;
b) CyDTA-zinc back titration method (without separation method).
4.2 Separation by cupferron-CyDTA-zinc back titration method
4.2.1 Principle
Hydrochloric acid is added to an aliquot portion of stock solution (S1) or (S′1), obtained in 4.2.2.3 or 4.2.3.3 of
ISO 21587-1:2007, to adjust the acidity. Iron, titanium, manganese and zirconium are separated from the
solution by solvent extraction with cupferron solution and the precipitate removed by dissolution in chloroform.
The organic phase is discarded. Excess standard volumetric CyDTA solution is added to the aqueous solution
after adjusting the pH with ammonia solution, and a chelate compound of aluminium CyDTA is formed. The
pH is further adjusted by the addition of ammonium acetate buffer solution and an equivalent volume of
ethanol is added to the solution. The amount of excess CyDTA is determined by back-titration with standard
volumetric zinc solution using dithizone as an indicator and the content of aluminium oxide calculated.
4.2.2 Procedure
Transfer a 100 ml aliquot portion of the stock solution (S1) or (S′1), obtained in 4.2.2.3 or 4.2.3.3 of
ISO 21587-1:2007, to a 500 ml separating funnel and add 20 ml of hydrochloric acid (concentrated) To the
solution, add 20 ml of chloroform and 10 ml of cupferron solution. Stopper the funnel and shake vigorously.
Release the pressure in the funnel by carefully removing the stopper and rinse the stopper and neck of the
funnel with a little water. Allow the layers to separate and withdraw the chloroform layer. Confirm that
extraction is complete by checking that the addition of a few drops of the cupferron solution to the aqueous
solution does not produce a permanent coloured precipitate. Add further 10 ml portions of the chloroform and
repeat the extraction until the chloroform layer is colourless. Wash the stem of the funnel, inside and out, with
chloroform, using a polyethylene wash bottle. Discard the chloroform extracts; do not allow them to dry as
there can be an explosion risk. Transfer the aqueous solution and washings from the funnel into a 1 l conical
flask. Add a few drops of bromophenol blue indicator and ammonia solution (concentrated) until the solution is
just alkaline. Re-acidify quickly with hydrochloric acid (concentrated) and add 5 to 6 drops in excess. Cool to
room temperature. Add sufficient standard volumetric CyDTA solution [c(CyDTA) = 0,05 mol/l] to combine with
the aluminium oxide present, and a few millilitres in excess.
NOTE 1 1 ml of standard volumetric CyDTA solution [c(CyDTA) = 0,05 mol/l] is equivalent to 1,275 % Al 0 for a
2 3
100 ml aliquot portion.
Add ammonium acetate buffer solution until the indicator turns blue, followed by 10 ml in excess. Add a
volume of the ethanol equal to the total volume of the solution. If sulfates are precipitated by the alcohol, add
just enough water to re-dissolve them. Add 20 ml of hydroxyammonium chloride and 1 ml to 2 ml of dithizone
indicator, and titrate with standard volumetric zinc solution [c(Zn) = 0,05 mol/l] from green to the first
appearance of a permanent pink colour.
NOTE 2 The end point is often improved by the addition of a little naphthol green B solution (1 g/l) to eliminate any pink
colour which can be formed in the solution on addition of the indicator.
4.2.3 Blank test
Transfer an aliquot portion of blank solution (B1) or (B′1) obtained in 4.2.2.4 or 4.2.3.4 of ISO 21587-1:2007
and carry out the procedure given in 4.2.2. Use the same volumes of the aliquot portion of blank solution (B1)
or (B′1) and standard volumetric CyDTA solution [c(CyDTA) = 0,05 mol/l] as those for the corresponding stock
solution (S1) or (S′1).
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ISO 21587-2:2007(E)
4.2.4 Calculation
Calculate the mass fraction of aluminium oxide in the sample as follows.
If the standard volumetric CyDTA solution [c(CyDTA) = 0,05 mol/l] is not exactly 0,05 mol/l, calculate the
equivalent volume of standard volumetric CyDTA solution.
Calculate the mass fraction of aluminium oxide, w , as a percentage, using the equation
Al O
2 3
w =−1,275VV (2)
()
Al O 1
23
where
V is the volume of standard volumetric CyDTA solution [c(CyDTA) = 0,05 mol/l] added, in ml;
V is the volume of standard volumetric zinc solution [c(Zn) = 0,05 mol/l] used in the back-titration, in ml,
1
for a 1 g test sample.
4.3 CyDTA-Zinc back titration method (without separation method)
4.3.1 Principle
Excess standard volumetric CyDTA solution is added to an aliquot of stock solution (S1) or (S′1). A chelate
compound of aluminium CyDTA is formed by adjusting the pH with ammonia water. The pH is further adjusted
by the addition of hexamethylenetetramine. The amount of remaining CyDTA is determined by back-titration
with standard volumetric zinc solution, using xylenol orange as an indicator. The content of aluminium oxide is
calculated by adjusting the content of iron(III) oxide, titanium(IV) oxide, manganese(II) oxide and zirconium
oxide by other methods.
4.3.2 Procedure
Determination is carried out in accordance with the following procedure.
Transfer precisely 50 ml of stock solution (S1) or (S′1), obtained in 4.2.2.3 or 4.2.3.3 of ISO 21587-1:2007, to
a beaker (300 ml), and add 2 ml of hydrochloric acid (1+1). Then add a precisely known amount of standard
volumetric CyDTA solution [c(CyDTA) = 0,02 mol/l], and dilute to 100 ml with water.
NOTE The relation between the volume of the aliquot of standard volumetric CyDTA solution [c(CyDTA) = 0,02 mol/l]
and the mass fraction of aluminum oxide, iron(III) oxide, and titanium(IV) oxide are shown in Table 1.
Table 1 — Aliquots of stock solution (S1) or (S′1) and volume of standard volumetric CyDTA solution
Sum of mass fractions of aluminum oxide, iron(III) Volume of standard volumetric
oxide and titanium(IV) oxide CyDTA solution
[c(CyDTA) = 0,02 mol/l]

% ml
less than 10 20
10 to 20 30
20 to 30 40
30 to 50 50

Add 1 g of hexamethylenetetramine and a drop of methyl orange solution as an indicator. Then, drop in
ammonia water (1+1), and ammonia water (1+9) of up to pH 3 indicating a slightly orange colour. If ammonia
4 © ISO 2007 – All rights reserved

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ISO 21587-2:2007(E)
water is added excessively, the pH is adjusted to less than 3 (showing a red colour) by adding hydrochloric
acid (1+1). Then, subsequently, carry out the identical adjustment. Add 5 g of hexamethylenetetramine of up
to pH 5,5 to 5,8, add 4 or 5 drops of xylenol orange solution as an indicator, and titrate with standard
volumetric zinc solution [c(Zn) = 0,02 mol/l]. In the vicinity of the end point, titration is carried out gently while
mixing, and the end point is decided when the colour changes from yellow to the first appearance of a
permanent reddish colour.
4.3.3 Blank test
Transfer an aliquot of blank solution (B1) or (B′1), obtained in 4.2.2.4 or 4.2.3.4 of ISO 21587-1:2007, and
carry out the procedure in accordance with 4.3.2. The volumes of the aliquot of blank solution (B1) or (B′1)
and standard volumetric CyDTA solution [c(CyDTA) = 0,02 mol/l] are the same as those for the corresponding
stock solution (S1) or (S′1).
4.3.4 Calculation
Calculate the mass fraction of aluminum oxide in the sample, w , as a percentage, using the following
Al O
2 3
equation:
VV−×F× 0,001019 6
( ) 500
21
w=×× 100−
Al O
23
m 50
(3)
⎡⎤
0,638×ww+ +×0,729w +×0,414w
()
Fe O TiO MnO ZrO
⎢⎥23 2 2
⎣⎦
where
V is the used quantity, in ml, of standard volumetric zinc solution [c(Zn) = 0,02 mol/l] in 4.3.2;
1
V is the used quantity, in ml, of standard volumetric zinc solution [c(Zn) = 0,02 mol/l] in 4.3.3;
2
F is the factor of standard volumetric zinc solution [c(Zn) = 0,02 mol/l];
m is the mass, in g, of sample in 4.2.2.2 or 4.2.3.2 in ISO 21587-1:2007;
w is the mass fraction, in %, of iron(III) oxide determined in Clause 5 or ISO 21587-3:2007
Fe O
2 3
(Clause 4);
w is the mass fraction, in %, of titanium(IV) oxide determined in Clause 6 or ISO 21587-3:2007
TiO
2
(Clause 5);
w is the mass fraction, in %, of manganese(II) oxide determined in Clause 7 or ISO 21587-3:2007
MnO
(Clause 6 or 18);
w is the mass fraction, in %, of zirconium oxide determined in Clause 13 or ISO 21587-3:2007
ZrO
2
(Clause 12).
5 Determination of iron(III) oxide
5.1 Principle
Two methods are given, using alternative reducing agents for the ferric oxide in solution. The iron in stock
solution (S1) or (S′1) is reduced with L(+)-ascorbic acid or hydroxyammonium chloride, 1,10-phenanthroline is
added, and the pH is adjusted by adding ammonium acetate. The absorbance is measured.
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ISO 21587-2:2007(E)
5.2 Procedure
Transfer 5 ml of stock solution (S1) or (S′1) obtained in 4.2.2.3 or 4.2.3.3 in ISO 21587-1:2007 into a 100 ml
volumetric flask.
5 ml of aliquot volume is a typical amount. An aliquot volume of stock solution (S1) or (S′1) should be adjusted
according to the mass fraction of iron(III) oxide in the sample as shown in Table 2.
Table 2 — Aliquot volume of stock solution (S1) or (S′1)
Mass fraction of iron(III)
Aliquot volume of stock solution (S1) or (S′1)
oxide
% ml
Less than 0,5 25
0,5 to 1,5 10
More than 1,5 5

Reduce the solution by one of the following methods.
a) Reduce with ascorbic acid by diluting to about 60 ml with water, and adding 5 ml of L(+)-tartaric acid
solution and 2 ml of L(+)-ascorbic acid solution while shaking. Add 10 ml of 1,10-phenanthrolinium
chloride solution (1 g/l) and 10 ml of ammonium acetate solution (20 %). Dilute to the mark with water,
then allow to stand for 30 min.
b) Reduce with hydroxyammonium chloride by adding 2 ml of hydroxyammonium chloride solution or L(+)
ascorbic acid solution (100 g/l), 5 ml of 1,10-phenanthroline solution (10 g/l) and 5 ml of ammonium
acetate solution (100 g/l). Allow the solution to stand for 15 min, dilute to the mark and mix. The colour is
stable between 15 min and 75 min after the addition of the ammonium acetate solution.
Measure the absorbance of the solution in a 10 mm cell at a wavelength of 510 nm or a colour filter against
water in a suitable instrument.
5.3 Blank test
Transfer the same volume of the blank solution (B1) or (B′1), obtained in 4.2.2.4 or 4.2.3.4 of
ISO 21587-1:2007, as that of stock solution (S1) or (S′1), and carry out the appropriate procedure given in 5.2
a) or b), as applicable.
5.4 Plotting the calibration graph
Transfer 0 (as reference), 5,0, 10,0 and 15,0 ml portions [0 mg to 0,6 mg as iron(III) oxide] of the dilute
standard iron(III) oxide solution (Fe O 0,04 mg/ml) into several 100 ml volumetric flasks. Treat these
2 3
solutions in accordance with 5.2 a) or b) and measure the absorbance against the reference solution. Then
plot the relation between the absorbances and mass of iron(III) oxide. Prepare the calibration graph by
adjusting the curve so that it passes through the point of origin.
5.5 Calculation
Calculate the mass fraction of iron(III) oxide in the sample, w , as a percentage, using the following
Fe O
2 3
equation. Use the amount of iron(III) oxide that is derived from the absorbance in 5.2 and the calibration in 5.4.
mm−
500
12
w =×× 100 (4)
Fe O
23
mV
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ISO 21587-2:2007(E)
where
m is the mass, in g, of iron(III) oxide in the aliquot portion of stock solution (S1) or (S′1);
1
m is the mass, in g, of iron(III) oxide in the aliquot portion of blank solution (B1) or (B′1);
2
m is the mass, in g, of the test portion in 4.2.2.3 or 4.2.3.3 in ISO 21587-1:2007;
V is the volume, in ml, of the aliquot portion taken from stock solution (S1) or (S′1) in 5.2, i.e. 5 ml.
6 Determination of titanium(IV) oxide
6.1 General
The determination of titanium(IV) oxide is carried out using one of the following methods:
a) di-antipyrylmethane (DAM) absorption spectrophotometric method;
b) hydrogen peroxide absorption spectrophotometric method.
6.2 DAM absorption spectrophotometric method
6.2.1 Principle
An aliquot portion of stock solution (S1) or (S′1) is adjusted for acidity. The iron is reduced with an addition of
L(+)-ascorbic acid and diantipyrylmethane. The absorbance of the colour produced is then measured.
6.2.2 Procedure
Carry out the determination using the following procedure.
Transfer 5 ml of stock solution (S1) or (S′1), obtained in 4.2.2.3 or 4.2.3.3 of ISO 21587-1:2007, into a 50 ml
volumetric flask.
5 ml of aliquot volume is a typical amount. An aliquot volume of stock solution (S1) or (S′1) should be adjusted
according to the mass fraction of titanium(IV) oxide in the sample as shown in Table 3.
Table 3 — Aliquot taken from stock solution (S1) or (S′1)
Mass fraction of titanium(IV) Aliquot taken
oxide
% ml
Less than 0,5 25
0,5 to 1,5 10
More than 1,5 5

Add 5 ml of hydrochloric acid (1+1) and 2 ml of L(+)-ascorbic acid solution, and allow to stand for 1 min, then
add 15 ml of DAM solution, and dilute to the mark with water. Allow the solution to stand for approximately
90 min. Measure the absorbance of the solution in a 10 mm cell at a wavelength of 390 nm against water.
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ISO 21587-2:2007(E)
6.2.3 Blank test
Using the same volume of blank solution (B1) or (B′1), obtained in 4.2.2.4 or 4.2.3.4 in ISO 21587-1:2007, as
that of stock solution (S1) or (S′1), carry out the procedure described in 6.2.2.
6.2.4 Plotting the calibration graph
Transfer 0 (as reference), 5, 10, 15, 20 and 25 ml aliquot portions [0 mg to 0,25 mg as titanium(IV) oxide] of
the dilute standard titanium(IV) oxide solution (TiO 0,01 mg/ml) into each of several 50 ml volumetric flasks.
2
Treat these solutions as in 6.2.3 and measure the absorbance against the reference solution. Plot the relation
between the absorbance and the amount of titanium(IV) oxide. Prepare the calibration graph by adjusting the
curve so that it passes through the point of origin.
6.2.5 Calculation
Calculate the mass fraction of titanium(IV) oxide, w , in the sample as a percentage, using the following
TiO
2
equation, with the amount of titanium
...