ISO/DIS 9285-2

ISO/TC 29/SC 5

Secretariat: DIN

Date: 2026-02-02

Oxide based abrasive grains — Chemical analysis —

Part 2:
Instrumental analysis

DIS stage

© ISO 2026

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Contents

Foreword

Scope

Normative references

Terms and definitions

Sampling

Sample Preparation

Apparatus

Procedure

Loss or gain of ignition

Apparatus

Procedure

Expression of results

Chemical analysis by X-ray fluorescence (XRF)

Setting up an RFA measurement

Chemical analysis by X-ray fluorescence on pressed powder pellets

Chemical analysis by X-ray fluorescence on fused beads

Measurement

Chemical analysis by inductively coupled plasma optical emission spectrometry (ICP-OES)

Digestion of the samples

Measurement

Chemical analysis by atomic absorption spectroscopy (AAS)

Materials

Apparatus

Calibration of the AAS

Analysis of carbon and sulphur by combustion gas analysis

Check and calibration

Materials

Apparatus

Preparation

Procedure

Evaluation

Test report

Bibliography

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.

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 document should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

ISO draws attention to the possibility that the implementation of this document may involve the use of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights in respect thereof. As of the date of publication of this document, ISO [had/had not] received notice of (a) patent(s) which may be required to implement this document. However, implementers are cautioned that this may not represent the latest information, which may be obtained from the patent database available at www.iso.org/patents.ISO shall not be held responsible for identifying any or all such patent rights.

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This document was prepared by Technical Committee ISO/TC 29 [Small tools], Subcommittee SC 5 [Grinding wheels and abrasives].

This edition cancels and replaces the edition (ISO 9285:1997), which has been technically revised.

The main changes are as follows:

• As part of the revision of ISO 9285:1997, the standard is divided into Part 1 and Part 2.
• Part 1 contains the classical wet chemical methods for quantitative chemical analysis.
• This document, Part 2, describes the methods of instrumental analysis. In addition, the scope of analysis is extended to include chromium oxide sodium oxide, potassium oxide and the oxides of lanthanides

A list of all parts in the ISO 9285 series can be found on the ISO website.

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.

Oxide based abrasive grains — Chemical analysis —

Part 2:
Instrumental analysis

This standard applies to the chemical analysis of oxidic abrasives consisting of one or more of following oxides: alumina, zirconia, magnesia, titania, silica, chromium oxide, calcium oxide, iron oxide, sodium oxide, potassium oxide and rare earth oxides.

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 Guide 30:2015, Reference materials — Selected terms and definitions

ISO 9138:2015, Abrasive grains — Sampling and splitting

For the purposes of this document, the following terms and definitions / terms and definitions given in Compendium of Terminology in Analytical Chemistry, ed. D. B. Hibbert, The Royal Society of Chemistry, 2023, pp apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp

The sample shall be taken according to ISO 9138:2015.

Methods described in chapter 6, 7 and 8 shall be carried out on samples finer than 150µm. Before chemical analysis by X-ray fluorescence analysis or inductive coupled plasma spectroscopy (chapter 5 and 6 in this document), it has to be ensured that the elements are fully oxidised. If necessary, the samples shall be heat treated in air for 2 hours at 1100°C.

• Laboratory jaw crusher
• Ball mill
• Hard metal grinding media (recommended)
• Scale accuracy of at least ± 0.001g
• Sieve mesh 2.5mm and 150µm
• Electric drying oven

If a sample is finer than 150 µm, it can be used directly without crushing. Coarser samples shall be processed by the following procedure.

Crush the sample in a laboratory jaw crusher to a grain size finer than 2.5 mm. Sieve the sample through a 2.5 mm sieve and crush the oversized residue. Homogenize the mixture after crushing

The sample can be reduced by using a sample splitter according to ISO 9138:2015.

Grind a sample of 100g (< 2.5 mm) in a suitable apparatus (e.g. vibration mill). Sieve the sample through a 150µm sieve, crush the oversized residue and sieve again. Continue in this manner until the whole sample has passed through the sieve. Mix the whole sample until it is homogenous.

Reduce the sample size to 25 g by using a sample splitter according to ISO 9138:2015 .

Dry the finely ground sample if necessary at 105 ± 5 °C until a constant mass is obtained.

Bauxite-based abrasives can contain magnetic phases. A magnetic separation would remove these along with contaminations from steel milling equipement which would falsify the results of analysis. To reduce such contamination, tungsten carbide milling tools can be used.

• Laboratory kiln
• Platinum crucible
• Desiccator filled with drying agent
• Scale accuracy of at least ± 0.001g

Weigh a sample of about 1 g (m0) into a weighed platinum crucible which has been previously heated 2 hours at 1100 °C. Record the weight of the sample and the crucible (m1). Heat the crucible plus sample to constant weight at 1100 °C. Cool the crucible in a desiccator. Weigh the crucible plus sample (m2).

Loss on ignition, expressed as a percentage, is given by the formula

(1)

where

NOTE lf the sample gains in mass, report as a gain, and use the formula:

(2)

The X-ray fluorescence spectrometer analyses the X-ray spectrum emitted from the sample after stimulation (or excitation) by a primary X-ray source. The elements present in a sample are emitting a set of characteristic X-rays, which are unique for each element. The intensity of the emitted characteristic X-rays is proportional to the concentration. Additional information can be found in ISO 12677 [1] . Information on operating the spectrometer and on the measurement, procedure shall be taken from the device manual.

The timeline for the calibration as well as the measurement of drift shall be carried out according to decvice specific requirements which are defined in the manual.

The setup of RFA measurements requires a sample specific calibration, which shall be based on measurements of a set of calibration standards. Calibration standards shall reflect the concentration range of elements and the combination thereof in the sample. Attention has to be paid on overlapping of lines.

The chemical composition of the calibration standards can be measured by reference laboratories. Synthetic reference samples for calibration can be made out of glass beads by using mixtures of pure oxides. Standards shall always be prepared in the same manner as sample materials.

The device-specific loss of intensity over time is called drift. Drift is caused by the ageing of the equipment e.g. the X-ray tube or the detector. The drift shall be measured with drift standards in defined intervals. For each chemical element, drift standards have to be prepared and results of drift measurements shall be used to minimize the effect of drift.

It is recommended to measure the drift with two samples of each element: one with low concentration and a second with high concentration.

When validation is required, validation samples with similar compositions of the sample shall be measured.

Powder samples can be analysed directly in pressed pellets. The usability of this technique depends on the influence of particle size distribution, particle composition, crystal structure effects, wavelength of analytical lines and the permissible total uncertainty. When more precise measurements are required, the use of fused beads (see clause 7.3) is recommended.

Before measurement the sample has to be transferred into a device-specific pellet.

• Pressing aid (For example: Hoechst Wax C “Micro powder tabletting-aid for XRF calibration standards”).
• Standards for calibration
• Diluting agent

All auxiliary additives e.g. compounds for calibration shall be certified in the quality p.a (= pro analysis) or AR (= analytical reagent), fulfilling the requirements of ISO Guide 30:2015.

• Press incl. spectrometer specific pressing tool
• Mortar and pestle for mixing

If necessary, the samples shall be treated as described in chapters 3 and 4 in this document and mixed with additives and diluents. The required grinding- and pressing parameters (sample size, size distribution, grinding aids, grinding time and pressure, holding time, use of supports), shall be determined experimentally and kept constant. More detailed information shall be taken from the spectrometer and press manuals.

The purpose of preparing fused glass beads is to convert the sample and a fluxing agent into a homogeneous melt that forms a glassy solid during cooling. The ions of the sample are dissolved in the glassy phase of the flux.

A precise description for preparation of glass beads as well as calibration is described in ISO 12677 [1].

Fluxing agents are made of elements which are not detected during the analysis. The fluxing agent shall be able to dissolve the oxides of the sample and form a stable homogeneous glass during solidification. The fused bead shall be as stable as possible. These requirements are best fulfilled by Lithiumborates. Lithiumborates are supplied by a number of reagent manufacturers. Preference can be given for lithiumborates made especially for X-ray fluorescence analysis because of their high purity, their high bulk density and excellent processability.

• Lithiumtetraborate Li₂B₄O₇ p.a.
• Lithiummetaborate LiBO₂ p.a.
• Pure oxides for calibration

• Crucibles and moulds made out of platinum alloys
• Automatic fluxing device or laboratory gas burner
• Desiccator filled with drying agent
• Crucible tongs

If necessary, the samples shall be treated as described in chapters 3 and 4 in this document. The sample as well as the lithiumborate flux has to be weighed with an accuracy of at least ±0.001g. The ratio of lithiummetaborate and lithiumtetraborate has to be adjusted to the sample by preliminary trials or by information given in the literature 4. The fusion process can be started directly after weighing; the temperature should be in the range of 900°C and 1150°C.

It is strongly recommended to increase the temperature slowly at the beginning. During fusion, the crucible shall be agitated to homogenize the melt. The fusion is finished when the melt is free of residues and bubbles. When the time for getting a homogenous melt is longer than 20 minutes, the composition of borates can be changed or additives can be added.

The liquid glass shall be poured on a preheated mould. Rapid cooling with an air stream can improve the long-term stability of the glass bead. A clear and homogeneous glass bead shall be generated. During cooling, no cracks shall occur.

It is recommended to use automatic fluxing devices because the reproducibility is higher.

Measurements shall be carried out according to the spectrometer manual. A measurement shall begin by measuring the drift intensity caused by the device. Results shall be corrected accordingly. When the drift is too high, the device has to be checked according to the manual and recalibrated.

The measurement is based on the intensity of the element-characteristic X-ray emission lines. The device-specific software shall calculate the chemical composition as well as the uncertainty of measurement, and generate a test report including the weight percent of each single oxide (see chapter 8 in this document).

A validation of the results can be carried out by measuring validation samples.

ICP-OES is a technique which determines the concentration of elements in water-based solutions. Further information on the subject can be found in the following document: EN ISO 21587-3 [2]. Solid samples need to be transferred (dissolved) in a water-based solution. The solution, including ions of the sample, is sprayed during the measurement in a plasma in which the elements’ electrons are thermally stimulated to emit light in characteristic wavelengths. The intensity of each line is proportional to the concentration if the corresponding ion. For calibration, commercially-available standard solutions or solutions of dissolved pure compounds or mixtures thereof can be used.

Transfer of solids into water-based solutions. Oxide-based abrasives are very stable and not easily to be dissolved.EN ISO 21079-1 [3]

In this method, two steps are required; first the digestion by lithiumborate flux into glass beads (described in chapter 7.3 in this document) and second, the dissolution of the lithiumborate glass beads into a water-based solution.

Materials

• Lithiumtetraborate Li₂B₄O₇
• Lithiummetaborate LiBO₂
• Deionized water.
• Hydrochloric acid 30%

Apparatus

• Crucibles and moulds made out of platinum alloys
• Automatic fluxing device (optional)
• Heat-resistant glass beaker
• Heating plate
• 250ml graduated flask

Procedure

For preparation of fused beads, see clause 7.3.1. The clear fused beads can be dissolved (for example, in 10ml HCl (30wt%) solution in a glass beaker). To increase the speed of dissolution, the mixture can be stirred and carefully heated. The clear solution shall be diluted with precision into a graduated 250 ml flask to be able to calculate the concentration of each element in the sample. A clear diluted solution shall be obtained.

This method is recommended when an analysis of trace elements is required.

WARNING — Special attention has to be paid to safety, because hazardous and toxic compounds are used. Carefully read all Material Safety Data Sheets (MSDS) and device-specific manuals!

A risk analysis shall be completed before any operations are performed. Only equipment made for microwave digestion (certified by supplier) shall be used in these operations.

Materials

• PSA (personal safety equipment)
• Sulfuric acid 96%
• Hydrofluoric acid 40%
• Hydrochloric acid 30%
• Phosphoric acid 85%
• Deionised water
• Boric oxide

Apparatus

• Laboratory equipment for analytical operations
• Crucibles made out of PTFE (Polytetrafluorethylene)
• Special microwave oven made for chemical digestion
• 250ml/1000ml graduated flask

Procedure

Fill a defined amount of sample and a defined amount of acid or a mixture of acids in the crucible. Close the crucible. Apply the device-specific procedure for the microwave oven being used. When hydrofluoric acid is used, a second step for neutralisation with boric oxide has to be applied. When the sample is not completely dissolved, the procedure has to be repeated or the ratio in the mixture has to be changed.

The clear solution shall be diluted precisely in a graduated flask for measurement.

• Standard solutions for ICP-OES
• Deionized water
• Compounds taken for digestion

• 250ml/1000ml graduated flask
• ICP-OES spectrometer

The spectrometer has to be calibrated according to the device-specific procedure. Standard solutions shall contain all chemical elements which have been used for digestion. The chemical composition of the standard solution shall be similar to that of the dissolved sample.

For evaluation, follow the device-specific instructions.

AAS is based on the principle that atoms in their ground state can absorb light at specific wavelengths characteristic to each element. Further information on the subject can be found in the following document: EN ISO 21079-3 [4]. The sample is atomized, usually by heat in a flame or graphite furnace. Light from a specific wavelength source (often a hollow cathode lamp) is passed through the atomized sample. The atoms of the element of interest absorb some of this light. A detector measures the amount of light absorbed, which is proportional to the concentration of the element in the sample.

• Certified reference materials (CRMs) or high-purity single-element standards
• Known concentration samples to monitor instrument performance
• Multi-element standard solutions (if analyzing multiple elements)
• Ultra-pure water
• Matrix-matched blank solution
• For flame AAS: fuel gases (e.g., acetylene, propane)

Types of AAS:

• Flame AAS: uses a flame to atomize the sample
• Graphite Furnace AAS: uses an electrically heated graphite tube for atomization

Components:

• Light source (typically a hollow cathode lamp)
• Atomizer (flame or graphite furnace)
• Monochromator (to isolate the specific wavelength)
• Detector
• Data processing system

Auxiliary equipment

• Pipette tips
• Sample cups or vial, graduated flasks

The spectrometer has to be calibrated according to the device-specific procedure with standard materials or standard solutions. Standard solutions shall contain all chemical elements which have been used for digestion. The chemical composition of the standard solution shall be similar to that of the dissolved sample.

Preparation of Standard Solutions

• Create a series of standard solutions with known concentrations of the element of interest.
• These solutions typically range from low to high concentrations within the expected range of the samples to be analyzed.

Blank Solution

Prepare a blank solution containing all reagents used in the sample preparation, but without the analyte.

Instrument Setup

• Set up the AAS according to the manufacturer's instructions.
• Select the appropriate hollow cathode lamp for the element being analyzed.
• Adjust wavelength, slit width, and other parameters as specified for the element.

Measurement of Standards

• Measure the absorbance of each standard solution, including the blank.
• Typically, start with the blank, then progress from lowest to highest concentration.

Calibration Curve

• Plot the absorbance values against the known concentrations of the standards.
• This should ideally result in a linear relationship (Beer-Lambert Law).

For measurement of the sample and the evaluation, follow the device-specific instructions.

Check that the values indicating the quality of the obtained results according to the device specific instructions

• Periodically recheck the calibration during a long series of measurements.
• Recalibrate if significant drift is observed.

For combustion analysis, the carbon- and sulphur-containing compounds are oxidised into CO₂ and SO₂. The combustion is supported by metallic accelerators which are heated via a high-frequency electric field. Both gases CO₂ and SO₂ are detected with an infrared gas analyser. For detailed information see EN ISO 21068-2 [5] .

Note: A heat treatment prior to this analysis shall not be applied. Samples can be directly analysed without milling.

The device shall be controlled in defined intervals by measuring a checking sample with defined amounts of carbon and sulphur. The amount of carbon and/or sulphur in the checking samples shall be similar to the expected amount in the sample.

A calibration of the device shall be carried out according to the device-specific procedure, described in the manual.

• Pressurized oxygen flask (purity of O2 recommended by the supplier of the device)
• Metallic iron chips (or other metal such as copper or tin) as accelerator
• Calibration standards
• Instrument-specific crucibles

• Instrument equipped with a furnace and infrared cells as detector (combustion analyser)
• Gas cleaning system
• Alumina crucibles
• Balance with at least ± 0.001 g accuracy

For this analysis, special attention has to be paid on carbon contamination. Samples can be taken without milling to avoid any contamination by carbides (e.g. tungsten carbide). For handling, crucible tongs shall be used.

A device-specific quantity of a dried sample shall be weighed precisely into the crucible and a defined quantity of accelerator shall be added. The ratio of accelerator and sample has to be checked out in advance for the type of sample.

The results are based on the specific absorption of infrared light by CO2 and SO2. The device specific software calculates the amount of elemental carbon and elemental sulphur.

Validation of results shall be carried out with standards whose contents are in the same range as those of the sample.

Results of chemical analysis carried out according to chapters 5 and 6 in this document shall be expressed as oxide in its stable oxidation number (see Table 1).

Table 1

The carbon and sulphur analysed by combustion analysis shall be expressed as carbon (free) in weight % C and sulphur (free) in weight % S.

Bibliography

[1] ISO 12677:2011, Chemical analysis of refractory products by X-ray fluorescence (XRF) — Fused cast-bead method

[2] EN ISO 21587-3:2007, Chemical analysis of aluminosilicate refractory products (alternative to the X-ray fluorescence method) - Part 3: Inductively coupled plasma and atomic absorption spectrometry methods (ISO 21587-3:2007)

[3] EN ISO 21079-1:2008, Chemical analysis of refractories containing alumina, zirconia and silica - Refractories containing 5 percent to 45 percent of ZrO2 (alternative to the X-ray fluorescence method) - Part 1: Apparatus, reagents and dissolution (ISO 21079-1:2008)

[4] EN ISO 21079-3:2008, Chemical analysis of refractories containing alumina, zirconia, and silica - Refractories containing 5 percent to 45 percent of ZrO2 (alternative to the X-ray fluorescence method) - Part 3: Flame atomic absorption spectrophotometry (FAAS) and inductively coupled plasma emission spectrometry (ICP -AES) (ISO 21079-3:2008)

[5] EN ISO 21068-2:2024, Chemical analysis of raw materials and refractory products containing silicon-carbide, silicon-nitride, silicon-oxynitride and sialon - Part 2: Determination of volatile components, total carbon, free carbon, silicon carbide, total and free silicon, free and surface silica (ISO 21068-2:2024)