EN ISO 12677:2011

SLOVENSKI STANDARD
01-december-2011
1DGRPHãþD
SIST EN ISO 12677:2003
Kemijska analiza ognjevzdržnih izdelkov z XRF - Metoda z vlito talino (ISO
12677:2011)
Chemical analysis of refractory products by X-ray fluorescence (XRF) - Fused cast-bead
method (ISO 12677:2011)
Chemische Analyse von feuerfesten Erzeugnissen durch RFA - Schmelzaufschluss-
Verfahren (ISO 12677:2011)
Analyse chimique des matériaux réfractaires par fluorescence de rayons X - Méthode de
la perle fondue (ISO 12677:2011)
Ta slovenski standard je istoveten z: EN ISO 12677:2011
ICS:
81.080 Ognjevzdržni materiali Refractories
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 12677
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2011
ICS 81.080 Supersedes EN ISO 12677:2003
English Version
Chemical analysis of refractory products by X-ray fluorescence
(XRF) - Fused cast-bead method (ISO 12677:2011)
Analyse chimique des matériaux réfractaires par Chemische Analyse von feuerfesten Erzeugnissen durch
fluorescence de rayons X - Méthode de la perle fondue Röntgenfluoreszenz-Analyse (RFA) - Schmelzaufschluss-
(ISO 12677:2011) Verfahren (ISO 12677:2011)
This European Standard was approved by CEN on 10 September 2011.

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, 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: Avenue Marnix 17, B-1000 Brussels
© 2011 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 12677:2011: E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
This document (EN ISO 12677:2011) has been prepared by Technical Committee ISO/TC 33 "Refractories" in
collaboration with 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 April 2012, and conflicting national standards shall be withdrawn at the
latest by April 2012.
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 supersedes EN ISO 12677:2003.
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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 12677:2011 has been approved by CEN as a EN ISO 12677:2011 without any modification.

INTERNATIONAL ISO
STANDARD 12677
Second edition
2011-10-01
Chemical analysis of refractory products
by X-ray fluorescence (XRF) — Fused
cast-bead method
Analyse chimique des matériaux réfractaires par fluorescence de
rayons X — Méthode de la perle fondue

Reference number
ISO 12677:2011(E)
©
ISO 2011
ISO 12677:2011(E)
©  ISO 2011
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56  CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2011 – All rights reserved

ISO 12677:2011(E)
Contents Page
Foreword . v
1  Scope . 1
2  Normative references . 1
3  Types of material . 1
4  Principle . 2
5  Apparatus . 2
6  Sample grinding . 3
7  Loss on ignition (and/or drying) . 4
8  Flux . 4
8.1  Choice of flux and ratio of flux to sample . 4
8.2  Compensations for moisture in flux . 5
9  Fusion casting procedures. 5
9.1  Fusion of samples and casting of beads . 5
9.2  Automatic bead preparation . 7
9.3  Storage . 7
9.4  Special problems . 8
10  Calibration . 8
10.1  Calibration standards . 8
10.2  Reagents and series reference materials (SeRMs) . 8
10.3  Calibration using reagents . 10
10.4  Calibration using SeRMs . 15
11  Corrections . 17
11.1  Line-overlap correction . 17
11.2  Background correction . 17
11.3  Drift correction . 18
11.4  Calculation of results . 18
11.5  Software requirements . 19
12  Reproducibility and repeatability . 20
12.1  Fusion tests . 20
12.2  Frequency of instrument tests . 20
12.3  Maximum allowance differences of sample holders . 20
12.4  Sample measuring positions . 21
12.5  Instrument repeatability . 21
12.6  Sequential systems . 21
12.7  Dead time . 22
12.8  Other tests . 22
12.9  Flow gas . 22
13  Accuracy determined by certified reference materials . 22
13.1  Validation of synthetic calibrations . 22
13.2  Validation of SeRM calibrations . 22
13.3  Fresh beads of the CRMs or synthetic standards used to check SeRM calibrations . 22
14  Definitions of limits of detection . 23
15  Test report . 23
ISO 12677:2011(E)
Annex A (normative) Calibration range and required detection limits .24
Annex B (normative) Corrections for tungsten carbide grinding media .28
Annex C (informative) Examples of fluxes/flux ratios .30
Annex D (normative) Examples of CRM to be used to check synthetic calibrations .32
Annex E (normative) Examples of SeRM .38
Annex F (normative) Equation for theoretical calculations .43
Annex G (normative) Certified reference materials (CRMs) .44
Annex H (normative) Method of inter-element correction used to compensate for the effects of
co-existing components when using SeRM for calibration .47
Annex I (normative) Standard deviations achieved with certified reference materials .68
Bibliography .75

iv © ISO 2011 – All rights reserved

ISO 12677:2011(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 12677 was prepared by Technical Committee ISO/TC 33, Refractories.
This second edition cancels and replaces the first edition (ISO 12677:2003), which has been technically
revised. Although the method in this International Standard has been considerably modified editorially and in
layout, the technical changes are limited. Some minor corrections have been made to certain equations. The
only significant changes are a reference to a further International Standard method (being prepared) for the
preparation of reduced materials for analysis by this standard, and instructions on how to add other
constituents to calibrations at the end of 10.2.1, Purity and preparation of reagents.

INTERNATIONAL STANDARD ISO 12677:2011(E)

Chemical analysis of refractory products by X-ray fluorescence
(XRF) — Fused cast-bead method
1 Scope
This International Standard specifies a method for the chemical analysis of refractory and technical ceramic
raw materials, intermediates and products, by means of the X-ray fluorescence (XRF) fused cast-bead
method. Typical materials that can be analysed by this standard are given in Clause 3. This International
Standard is not applicable to non-oxide materials, such as silicon carbides or nitrides, etc. The method is
applicable to a wide range of materials containing a wide range of elements.
NOTE 1 The presence of significant amounts of certain elements, such as tin, copper, zinc and chromium, can present
difficulties in the fusion process. In this case, the Bibliography can be referred to.
NOTE 2 Constituents at concentrations greater than 99 % (on a dried basis) are reported by difference, provided that
all likely minor constituents and any loss on ignition have been determined. These figures can also be checked by direct
determination.
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 Guide 35:2006, Reference materials — General and statistical principles for certification
ISO 565, Test sieves — Metal wire cloth, perforated metal plate and electroformed sheet — Nominal sizes of
openings
ISO 26845, Chemical analysis of refractories — General requirements for wet chemical analysis, atomic
absorption spectrometry (AAS) and inductively coupled plasma atomic emission spectrometry (ICP-AES)
methods
3 Types of material
Listed below are various types of ceramic material that have been successfully analysed by this method and
for which statistical data is available (see Annex I). The list is not exhaustive but serves as a guide to those
using this International Standard for the first time.
a) High alumina  45 % Al O
2 3
b) Alumino-silicate 7 % to 45 % Al O
2 3
c) Silica  93 % SiO
d) Zircon
e) Zirconia and zirconates
f) Magnesia
ISO 12677:2011(E)
g) Magnesia/alumina spinel (70/30)
h) Dolomite
i) Limestone
j) Magnesia/chromic oxide
k) Chrome ore
l) Chrome-alumina
m) Alumina/magnesia spinel (70/30)
n) Zirconia-alumina-silica cast material (AZS)
o) Calcium silicates
p) Calcium aluminates
q) Magnesium silicates
A list of elemental ranges and required detection limits are given in Annex A.
NOTE 1 Some of the above material types can be accommodated for common calibrations (see 10.3.4).
NOTE 2 Reduced materials, such as silicon carbide, cannot be determined directly by this International Standard and
so are not listed above. Such materials require special methods both for loss on ignition and fusion into a bead prior to
XRF analysis. Suitable procedures are described in ISO 21068-1, ISO 21068-2 and ISO 21068-3 and further methods are
under development by the refractory standards system. Once reduced materials are suitably ignited and subsequently
prepared as fused beads, this standard can be applied to the rest of the procedure.
WARNING — Failure to pretreat reduced materials, such as silicon carbide, properly not only leads to
erroneous results but will also cause damage to valuable platinum alloy crucibles and dishes.
4 Principle
The powdered sample is fused with a suitable flux to destroy its mineralogical and particulate composition.
The resultant melt is cast into the shape of a glass bead which is then introduced into an XRF spectrometer.
The intensities of the fluorescent X-rays of the required elements in the bead are measured and the chemical
composition of the sample is analysed by reference to previously determined calibration graphs or equations
and applying corrections for inter-element effects. The calibration equations and inter-element corrections are
established from beads produced using pure reagents and/or series reference materials (SeRMs), prepared in
the same way as the samples. Certified reference materials (CRMs) may be used providing they meet all the
requirements of 10.2.2 and 10.4.1.
Because of the universality of the fused cast-bead technique, various fluxes and modes of calibration are
permitted, providing they have been demonstrated as being able to meet certain criteria of repeatability,
sensitivity and accuracy. Provided that a laboratory's own methods conform to all the various criteria set down,
they will be accepted as conforming to this International Standard.
5 Apparatus
5.1 Fusion vessels, of a non-wetted platinum alloy (Pt/Au 95 %/5 % is suitable). Lids, if used, shall be of a
platinum alloy (not necessarily non-wetted).
NOTE A useful guide to the care of platinum is given in Reference [5] of the Bibliography.
5.2 Casting moulds, of a non-wetted platinum alloy (Pt/Au 95 %/5 % is suitable).
NOTE Vessels that serve both as fusion vessels and casting moulds can be used.
2 © ISO 2011 – All rights reserved

ISO 12677:2011(E)
5.3 Heat reservoir for casting mould (optional), required in special circumstances when using moulds of
small sizes, so that the mould does not cool too rapidly when removed from the furnace. A small piece of flat
refractory material is suitable, e.g. a piece of sillimanite batt with dimensions 10 mm  50 mm  50 mm.
5.4 Air jet (optional), required to cool the mould rapidly. This may be any device whereon a narrow jet of air
can be directed to the centre of the base of the casting dish. A convenient way of doing this is to use the base
of a Bunsen burner without a barrel to serve as an air jet.
NOTE In most cases, it is very important to cool the melt rapidly. This is necessary to obtain a homogeneous bead
and to free the melt from the dish.
A water-cooled metal plate may also be used.
5.5 Fusion apparatus, electric resistance furnaces or high-frequency induction furnaces that may be
heated up to a fixed temperature of between 1 050 °C and 1 250 °C may be used.
5.6 Automatic fusion apparatus, for use in automatic bead preparation (see 9.2) where required.
5.7 Balance, capable of weighing to 0,1 mg.
5.8 Mechanical mixer, that moves in a linear or rotary way.
NOTE Vibratory mixers cannot be used as they induce segregation.
6 Sample grinding
This International Standard shall start with a laboratory sample.
NOTE 1 Bulk sampling is not within the scope of this method but can be found in ISO 26845.
The sample shall be ground using tungsten carbide. The appropriate corrections for tungsten carbide (and its
binder if necessary) shall be applied to loss on ignition and analysis figures in accordance with Annex B.
NOTE 2 It is permissible to apply the sample grinding methods cited in conventional chemical methods for the classes
of materials covered. However, the tungsten carbide method is the preferred method.
The maximum particle size shall be 100 µm.
NOTE 3 The purpose of grinding is to obtain a sample sufficiently fine to be fused easily but below a set limit of
introduced contamination. But for certain samples that are difficult to fuse (e.g. chrome ores), finer grinding to less than
60 µm might be necessary.
One of the following two methods shall be used to obtain the required particle size.
a) For mechanical grinding devices, establish what grinding times are sufficient to grind the various samples
to be analysed to the correct fineness and thereafter apply these minimum times for grinding. In order to
establish grinding times, use the mechanical grinder to prepare typical materials analysed for
progressively increasing lengths of time of 2 min. Sieve each ground sample through a 100 µm sieve
until a grinding time is reached where the entire sample passes through the sieve. Then use this time for
that material or the longest time of any material analysed, if applied to all materials. When grinding hard
materials, such as chromite, sieving shall be used, but this might induce segregation. Therefore, after
sieving, the sample shall be mixed thoroughly by stirring or tumbling prior to transferring to a sample tube.
Because heavier minerals can segregate on standing, it is advisable to stir the sample once more, prior to
weighing out.
b) After hand-grinding for 20 s, sieve the ground powder through a sieve of 100 µm aperture, in accordance
with ISO 565. Regrind any material remaining on the sieve for a further 20 s, sieve and repeat this
procedure until the whole of the sample passes through the sieve. Transfer the sample to a suitable
container and mix for 1 min, using a mechanical mixer such as a vertical linear mixer.
ISO 12677:2011(E)
NOTE 4 As the object of the exercise is to obtain a sample suitable for fusion, and not to test the fineness of the
sample itself, method a) is generally preferred.
7 Loss on ignition (and/or drying)
Loss on ignition shall be carried out in accordance with ISO 26845.
8 Flux
8.1 Choice of flux and ratio of flux to sample
8.1.1 One of the advantages of the XRF fused cast-bead method is that a wide variety of fluxes may be
chosen. For a given calibration, the same flux shall be used throughout. The conditions given in 8.1.2 to 8.1.9
shall be met for any flux and flux/sample ratio used.
NOTE Fluxes used with success in the analysis of refractory materials are given in Annex C. Prefused fluxes have
the advantage of lower moisture contents.
8.1.2 Under the conditions of preparation used, the sample shall be totally dissolved by the flux and shall
not come out of solution during the casting procedure.
8.1.3 The resulting bead shall be transparent and show no signs of devitrification.
8.1.4 At a reasonably high counting time (200 s), the required detection limits shall be achieved for the
elements determined. Detection limits are defined as in Clause 14 and listed in Annex A.
8.1.5 At a reasonable counting time (200 s), the counts recorded for each element determined shall give
the required standard of repeatability for the determination of that element (as measured according to 12.1
and defined as in G.1).
8.1.6 A heavy element absorber may be incorporated into the flux provided that:
a) it does not reduce sensitivities so that conditions 8.1.4 and 8.1.5 are not met;
b) the heavy element does not have a line overlap with any of the elements to be determined.
8.1.7 If volatile components are to be determined, then a flux of sufficiently low melting point, which permits
a fusion temperature low enough to retain that element during fusion, shall be used.
8.1.8 For the determination of elements that alloy with platinum (e.g. lead, zinc, cobalt), the melting point
shall be such as to allow fusion below the temperature at which this reaction occurs (1 050 °C).
8.1.9 The flux shall be pure with respect to the analytes determined. As the flux to sample ratio is greater
than 1 (see Annex C), impurities to the flux can influence the measured result negatively. The greater the ratio
of the flux to sample, the greater the influence. Therefore, the permitted levels of impurity of analyte levels in
the flux shall be no more than:
D/(3R)
where
R is the ratio of flux to sample;
D is the detection limit claimed for the determination of the analyte element.
Most reagents sold by reputable manufacturers as “flux” grade quality meet this requirement but an analysis
shall be obtained for each batch of flux supplied. Recheck calibrations when batches of flux are changed.
4 © ISO 2011 – All rights reserved

ISO 12677:2011(E)
8.2 Compensations for moisture in flux
The flux contains a certain amount of moisture, which shall be compensated for in one of two ways.
a) Calcine the entire quantity of flux required overnight at 700 °C immediately before it is used for analysis,
and store it in a desiccator.
b) Carry out duplicate losses on ignition on 1 g portions of well-mixed flux for each kilogram of flux used.
Carry out the calcining at the normal fusion temperature for 10 min, or the normal fusion time, whichever
is the greater [see 9.1.2 f)]. Store the flux in a tightly sealed container except when in use. The loss on
ignition, expressed as a percentage by mass, w , is then used to calculate a flux factor, F [see
L
Equation (1)], which is in turn used to calculate the mass of the unignited flux needed to produce the
required mass of flux on the ignited basis (F times the required mass of ignited flux  required mass of
unignited flux). Carry out this loss on ignition at weekly intervals or for each kilogram of flux used,
whichever is the more frequent.
F (1)
100 w
L
NOTE The compensation might be unnecessary if the loss on ignition is 0,50 % or lower (prefused fluxes).
9 Fusion casting procedures
9.1 Fusion of samples and casting of beads
9.1.1 Choice of procedure
At several of the stages, a choice of procedures is given. Once a choice has been made, the procedure shall
be adhered to throughout, unless a total recalibration is carried out.
9.1.2 Requirements
Before fusing the samples and casting the beads, the following requirements shall be satisfied.
a) Duplicate or single beads may be prepared; the number used shall be stated in the test report.
b) The total mass of sample and flux shall be chosen for the particular casting-mould type used, and this
mass shall always be the same.
c) The ratio, R, by mass of the flux to that of the sample, shall be the same for the material type analysed.
d) The melts produced shall be visually homogeneous.
e) There shall be no measurable loss of any component from the sample during fusion, e.g. loss by
reduction or evaporation (excessive temperature).
f) The variations of any loss of flux shall be minimized by using consistent times and temperature during
fusion in the preparation of both calibration standards and samples.
g) The sample shall not be contaminated in any way by the sample preparation by any constituent being
measured on that sub-sample. This can either be established by knowing the composition of the grinding
media or by measuring the amount of contamination added in grinding pure materials or materials of
known composition.
h) The beads produced shall be free from blemishes on the chosen measuring surface.
i) If the top surface of the bead is to be used for analysis, it shall be either convex or flat and be symmetrical
across any diameter.
ISO 12677:2011(E)
j) Standard glass beads of known composition shall be prepared in the same way as sample beads.
k) If moulds become distorted in use, they shall be reshaped by pressing in a suitable former. If the bottom
(flat) surface of the bead is used for analysis, the top surface of the mould shall also be kept flat and free
from blemishes.
l) Beads shall be infinitely thick for the X-ray wavelengths measured. For line parameters used in refractory
analysis, infinite thickness is normally achieved.
NOTE 1 Duplicate beads are preferable to single beads. However, if all the oxides given in Annex A are determined for
the relevant class of material, an analytical total will be achieved, which acts as a check on the result of analysis.
NOTE 2 Fusions at 1 200 °C will volatilize certain elements, e.g. sulfur, even when an oxidizing agent is used.
9.1.3 Conversion of the sample to bead form
The sample to be analysed may be converted into bead form in a number of ways.
a) Calcine the sample to constant mass at (1 025  25) °C, desiccate and allow to cool to room temperature.
Weigh it in the fusion dish and record the mass, m, to the nearest 0,000 1 g. Weigh the flux samples as
described in 8.2.
b) Take a sample of uncalcined flux of mass R · m · F and mix thoroughly with the sample, where F is the flux
factor determined in 8.2 b). Dry the sample to constant mass at (110  10) °C. Weigh in the fusion dish
and record, to the nearest 0,000 1 g, the sample mass
w
L
m1%


where w is the percentage by mass of sample lost during ignition at (1 025  25) °C.
L
As in item a), the sample may be mixed with either calcined or uncalcined flux.
NOTE 1 For problems affecting the fusion of materials containing chromium oxide or zirconia, see 9.4.
Fuse the sample and flux together, with occasional swirling, until the sample is seen to be dissolved and the
melt homogeneous.
During the initial part of the fusion process, fuse carbonate samples slowly to avoid “spurting” (ejection of
sample or flux).
NOTE 2 In the case of limestone, dolomite and magnesium carbonate, it is preferable to weigh out an amount of the
dried sample, corrected for loss on ignition, for fusion.
NOTE 3 The fusion temperature can be specified according to material type.
9.1.4 Manual casting of beads
9.1.4.1 General
The final part of the fusion process consists of heating the fusion vessel, the mould and the heat reservoir (if
used) in a muffle furnace (1 200  50) °C for 5 min. Then cast the beads using one of the following methods.
a) Outside the furnace: after 5 min at (1 200  50) °C, remove the heat reservoir (5.3) from the furnace
(5.5) and place it on a horizontal surface. Immediately place the mould onto the heat reservoir. Then
remove the lid from the fusion vessel and immediately pour the melt into the casting mould (5.2).
6 © ISO 2011 – All rights reserved

ISO 12677:2011(E)
b) In the furnace: after 5 min at (1 200  50) °C, remove the lid from the fusion vessel (5.1) and pour the
melt into the mould (5.2) inside the furnace (5.5), ensuring that as much of the melt is transferred to the
mould as possible. Remove the mould from the furnace and place it on a horizontal surface.
c) Combined fusion mould: after 5 min at (1 200  50) °C, remove the fusion vessel from the furnace. If a
releasing agent is not used, the melt can rise up the sides of the vessel. Therefore, careful manipulation
of the vessel is required to work the melt into the mould part of the vessel. Then put the fusion vessel on
a graphite brick to cool.
d) Mould heated over a burner: after preparation of the melt at the fusion temperature and the time chosen
for that type of material, pour the melt into the preheated mould and turn the burner off. Allow the melt to
solidify and use an air jet (5.4), as described in 9.1.4.2., or a water-cooled metal plate to accelerate the
cooling process.
When the top surface of the bead is used [not c)] for subsequent analysis, a rippled surface produced in the
casting process can lead to erroneous results. In order to avoid this rippled effect, the melt should be poured
into the mould at a point nearer to the edge of the mould than the centre. When using top surfaces, in order to
maintain a uniform curvature on the top surface, it is necessary to get as much of the melt into the casting
mould as possible, so as to achieve consistent bead masses.
NOTE Most refractory materials contain small amounts (as low as 0,1 %) of Cr O , ZrO , and -Al O which, if the
2 3 2 2 3
fusion is not completed at (1 200  50) °C, will cause the melt to devitrify. However, if experience shows that de-
vetrification is not a problem, samples can be cast in furnaces at as low as (1 050  25) °C, providing calibration standards
are prepared the same way.
Small amounts of lithium iodide or iodate, or ammonium iodate, may be added to the melt to assist in
preventing cracking of fused beads on cooling and to aid release from the mould. Iodine does have a small
line overlap with TiK, so if low levels of TiO are to be determined, corrections may be needed. If small
amounts of releasing agents are to be used, then all samples and any calibration standards prepared should
include the same releasing agent added in the same quantity and at the same stage of bead preparation.
Maintaining a good polish on the casting moulds should obviate the need for such agents, but there are further
problems with samples containing high levels of Cr O . It is also possible to use NH Br or LiBr but it should be
2 3 4
noted that there is a Br L line near the Al K line. High amounts of Br may cause serious line-overlap
problems when measuring low alumina concentrations and corrections may need to be applied. For low levels
of Al O , iodide or iodate is recommended. The amount of NH Br or LiBr added should not exceed 1 mg per
2 3 4
gram of sample. If a chromium tube is used, the effect of bromine will be greater; therefore, the effect of
bromine on aluminium should be checked before using a bromine-based releasing agent.
9.1.4.2 Cooling of beads
If no air jet is used, allow the mould to cool on a horizontal surface. If the air jet is used, transfer the mould to it
when the melt has cooled from red heat. The melt may be molten or solid at this stage; if it is molten and top
surfaces are to be measured, ensure that the support over the air jet is horizontal.
Hold the dish in a horizontal position above the air jet so that the air is directed onto the centre of the base of
the mould. When the bead has solidified and released itself, turn off the air jet.
NOTE It might be necessary to encourage the release of the beads at this stage by gently tapping the casting mould
on a solid surface.
9.2 Automatic bead preparation
Automatic bead equipment may be used as an alternative to 9.1.4, and shall be in accordance with 9.1.2
and 12.1.
9.3 Storage
Beads can deteriorate because of adverse temperature and humidity conditions. Therefore they should be
stored in such a manner as to avoid hydration and contamination.
ISO 12677:2011(E)
The measuring surfaces of beads shall be thoroughly cleaned before use, or possibly polished after long-term
storage.
NOTE Reported sources of contamination are as follows:
a) sulfur from vacuum oil in the spectrometer or from the laboratory atmosphere;
b) sodium and chlorine from the atmosphere if the laboratory is near the sea;
c) potassium from cigarette smoke;
d) contamination from the surface of plastic bags that may be used for storing the beads.
9.4 Special problems
Samples with high chromium oxide or zirconia content can create problems during fusion. Chromium oxide is
difficult to dissolve in the molten flux and zirconia also suffers from this problem to a lesser degree but can
also cause devitrification on cooling, even after complete dissolution. Before establishing methods of fusion for
these materials, fusion trials are required to establish a method for preparing the samples of the highest
content of these oxides, likely to be encountered by the laboratory. In these trials, optimum flux, sample/flux
ratio, temperatures and fusion times need to be established. Normally, different procedures will be required for
chrome-bearing material, zircon and zirconia.
NOTE Even if the storage conditions in 9.3 are observed, beads containing high levels of ZrO tend to absorb
moisture onto the surface more than other beads. This causes increased backgrounds on light elements. The problem can
be cured by drying the bead overnight at 220 °C.
10 Calibration
10.1 Calibration standards
The calibration equations and inter-element corrections are established using beads produced with pure
reagents or series reference materials (SeRMs). The SeRMs are different from certified reference materials
(CRMs) which validate the calibrations using pure reagents. CRMs and SeRMs are shown in Annexes D and E,
respectively. The series of CRMs meeting the requirements of 10.2.2 and 10.4.1 may be regarded as SeRMs.
10.2 Reagents and series reference materials (SeRMs)
10.2.1 Purity and preparation of reagents
The reagents used to prepare the standard beads for cations shall be pure oxides or carbonates of at least
99,95 % purity (excluding moisture or CO ) for minor constituents and of at least 99,99 % purity for silica and
alumina. For the calibration of elements such as sulfur or phosphorus which do not form stable oxides or
carbonates, some guarantee of stoichiometry is required.
It is essential that the reagents be free of (or corrected for) the presence of water (and, in the case of oxides,
carbon dioxide) when weighed out for fusion. Also, the reagents shall be in a known oxidation state.
The procedures listed ensure that the correct oxidation state is obtained. The reagents used for calibration
shall be of high purity and, when fresh batches of reagents are purchased, they shall be compared with
previous batches. Therefore, a fresh bead shall be made at the highest level of content calibrated and
measured against a similar bead prepared from the previous batch of the same reagent. The intensities
achieved for elements other than those in the reagent shall not differ by more than the detection limit for that
element.
In order to obtain the reagents of a known stoichiometry in terms of content, they shall be treated before use
as follows.
a) Silica, alumina and magnesia: determine the loss on ignition as follows. Calcine 5 g of the material, as
received, at (1 200  50) °C and keep them at this temperature for a minimum of 30 min. Cool in a
8 © ISO 2011 – All rights reserved

ISO 12677:2011(E)
desiccator to room temperature and reweigh. After allowing for this loss, weigh the appropriate amount of
the uncalcined material to prepare the standard bead.
b) Manganese oxide (Mn O ), titanium(IV) oxide and nickel(II) oxide, chromium(III) oxide, zirconia, hafnia,
3 4
ceria, yttria, lanthia and other rare earths. Calcine 5 g of the material at (1 000  25) °C and keep them at
this temperature for a minimum of 30 min. Cool in a desiccator to room temperature before use.
NOTE 1 Rare earths absorb water and carbon dioxide from the atmosphere.
c) Iron(III) oxide, tin(IV) oxide, cobalt oxide (Co O ) and lithium orthophosphate. Calcine 5 g of the material
3 4
at (700  25) °C and keep them at this temperature for a minimum of 30 min. Cool in a desiccator to room
temperature before use.
d) Calcium carbonate, barium and strontium carbonates, potassium and sodium carbonates, tungstic oxide,
gallium oxide, lithium sulfate. Dry the material at (230  20) °C before use. Cool in a desiccator to room
temperature before use.
Other oxides may be added to calibrations, as long as the oxides or their compounds used for the calibration
are of a sufficient purity and of guaranteed stoichiometry by heat treatment, etc. In addition, problems
regarding volatility of that element/oxide in fusion are taken into account, as well as any tendency for the
element to alloy with the fusion vessel during the fusion process. A list of useful references to deal with these
points is given in References [5] to [9]. This list is not exhaustive and other references may also be of use. In
addition, the calibrations should meet the other requirements of this International Standard.
NOTE 2 A 2 h treatment is usually sufficient for drying.
Tungsten carbide (WC) will be introduced as a contaminant if this media is used for grinding. Laboratories
using tungsten carbide for sample grinding should calibrate for WO in order to monitor its presence in
samples, and hence correct the analysis and the loss on ignition for WC contamination (see Annex B). Unlike
the wet chemical analysis procedure, X-ray fluorescence determinations are not subject to any significant
cross interference due to tungsten and furthermore the contaminating tungsten may be easily monitored.
If tungsten contamination exceeds 0,5 %, corrections shall be applied. See Annex B.
10.2.2 Preparation of series reference materials (SeRMs)
SeRMs may be used for calibration instead of synthetic standards. The SeRMs shall cover the following points.
a) SeRMs
...