ISO 10478:1994

Petroleum products - Determination of aluminium and silicon in fuel oils - Inductively coupled plasma emission and atomic absorption spectroscopy methods

The principle of the method specified is heating a weighed quantity of homogenized sample in a clean platinum basin, removing the combustible material by burning, finally removing the carbon by heating, fusing the residue with a dilithium tetraborate/lithium fluoride flux, digesting the fused mixture in a solution of tartaric acid and hydrochloric acid, dilution to volume with water, measuring the solution by ICPES or AAS. The method is applicable for concentrations between 5 mg/kg and 150 mg/kg for aluminium and 10 mg/kg and 250 mg/kg for silicon.

Produits pétroliers — Détermination de l'aluminium et du silicium dans les combustibles — Méthodes par spectroscopie d'émission à plasma induit et spectroscopie d'absorption atomique

General Information

• Status: Published
• Publication Date: 13-Jul-1994
• ICS: 75.160.20 - Liquid fuels
• Technical Committee: ISO/TC 28 - Petroleum and related products, fuels and lubricants from natural or synthetic sources
• Drafting Committee: ISO/TC 28/WG 24 - Elemental analysis
• Current Stage: 9093 - International Standard confirmed
• Start Date: 20-May-2021
• Completion Date: 13-Dec-2025

Overview

ISO 10478:1994 specifies laboratory methods for the determination of aluminium (Al) and silicon (Si) in fuel oils using inductively coupled plasma emission spectroscopy (ICPES) and atomic absorption spectroscopy (AAS). The method uses a heat/fusion digestion followed by acid digestion and instrumental measurement. It is applicable for Al concentrations 5–150 mg/kg and Si concentrations 10–250 mg/kg in fuel oil matrices.

Key topics and technical requirements

• Sample preparation
  • Thorough homogenization of the fuel-oil sample and transfer of a weighed test portion (typically 20–50 g).
  • Removal of combustible material by controlled ignition in a platinum basin and complete carbon removal in a muffle furnace (typical temperatures noted: ~550 °C for ashing, ~925 °C for fusion step).
• Fusion and digestion
  • Fusion of the residual ash with a flux composed of 90% dilithium tetraborate (Li2B4O7) and 10% lithium fluoride (LiF).
  • Dissolution/digestion of the fusion melt in a tartaric acid / hydrochloric acid solution and dilution to volume.
• Reagents and cleaning
  • Use of analytical-grade reagents and water (ISO 3696 grade 3 or better).
  • Cleaning of platinum basins with molten potassium hydrogensulfate (KHSO4) to avoid contamination.
• Calibration and blanks
  • Preparation of aluminium and silicon calibration standards (working ranges described in the standard) and a blank solution containing flux/tartaric acid matrix.
  • Regular calibration checks (e.g., one standard after every five samples) and sample dilutions in the same matrix if concentrations exceed calibration range.
• Instrumental measurement
  • Measurement by ICPES or AAS with specified operational considerations (e.g., warm-up, wavelength profiling).
  • Example analytical wavelengths cited in the standard: Al - 309.3 nm, Si - 251.6 nm; flame fuel/oxidant: acetylene / dinitrogen oxide for AAS operation.

Applications and users

• Typical users: analytical laboratories, refinery quality-control teams, fuel testing labs, petrochemical R&D, and regulatory bodies concerned with trace metal content in fuel oils.
• Practical uses:
  • Monitoring contamination from processing equipment (e.g., aluminium-containing corrosion products) and silicon-based additives or contaminants.
  • Ensuring compliance with fuel specifications and assessing potential impacts on engines, catalysts, and refinery operations.
  • Routine QC testing and failure-investigation analyses.

Related standards

• ISO 3696 (Water for analytical laboratory use)
• ISO 1042 (Volumetric flasks)
• ISO 648, ISO 835-2, ISO 3819, ISO 4788 (laboratory glassware references cited within ISO 10478)

Keywords: ISO 10478, aluminium in fuel oils, silicon in fuel oils, ICPES, AAS, fuel oil analysis, sample fusion, dilithium tetraborate flux, tartaric acid digestion.

Standards Content (Sample)

INTERNATIONAL
ISO
STANDARD
First edition
1994-08-01
Petroleum products - Determination of
aluminium and Silicon in fuel oils -
Inductively coupled Plasma emission and
atomic absorption spectroscopy methods
Produits petroliers - D&ermina tion de I ’aluminium et du silicium dans /es
combus tibles - M&hodes par spectroscopie d Smission 2 Plasma induit
et spectroscopie d ’absorption a tomique
Reference number
ISO 10478: 1994(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. Esch 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
(1 EC) on all matters of electrotechnical standardization.
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.
International Standard ISO 10478 was prepared by Technical Committee
lSO/TC 28, Petroleum products and lubricants.
0 ISO 1994
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronie or mechanical, including photocopying and
microfilm, without Permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-l 211 Geneve 20 l Switzerland
Printed in Switzerland
~~~ ~~
INTERNATIONAL STANDARD 0 ISO ISO 10478:1994(E)
Petroleum products - Determination of aluminium
and silicon in fuel oils - Inductively coupled Plasma
emission and atomic absorption spectroscopy
methods
WARNDNG - The use of this International Standard may involve hazardous materials, operations
and equipment. This Standard does not purport to address all of the safety Problems associated
with its use. It is the responsibility of the User of this Standard to establish appropriate safety and
health practices and determine the applicability of regulatory limitations Prior to use.
ISO 1042:1983, Laboratory glassware - One-mark
1 Scope
volume tric flasks.
This International Standard specifies a method for
ISO 3696:1987, Water for analytical laboratory use -
determining the aluminium and Silicon contents of
Specifica tion and test methods.
fuel oils at concentrations between 5 mg/kg and
150 mg/kg for aluminium and 10 mg/kg and
ISO 3819:1985, Laboratory glassware - Beakers.
250 mg/kg for Silicon using inductively coupled
Plasma emission and atomic absorption spectroscopy.
ISO 478811980, Laboratory glassware - Graduated
measuring cylinders.
3 Principle
2 Normative references
A weighed quantity of homogenized Sample is heated
in a clean platinum basin, the combustible material
The following Standards contain provisions which,
removed by burning and the carbon finally removed
through reference in this text, constitute provisions
by heating in a muffle furnace at a temperature of
of this International Standard. At the time of publi-
cation, the editions indicated were valid. All Standards 550 “C + 25 “C. The residue is fused with a dilithium
are subject to revision, and Parties to agreements tetraboratellithium fluoride flux, the fused mixture di-
based on this International Standard are encouraged gested in a Solution of tartaric acid and hydrochloric
to investigate the possibility of applying the most re- acid, and diluted to volume with water.
cent editions of the Standards indicated below.
The Solution is aspirated into either the Plasma of an
Members of IEC and ISO maintain registers of cur-
inductively coupled Plasma emission spectrometer
rently valid International Standards.
(ICPES), and the emission radiation of the resonance
lines of aluminium/silicon measured and compared
ISO 648: 1977, Laboratory glassware - One-mark
with that of Standard calibration solutions, or the
pipettes.
flame of an atomic absorption spectrometer (AAS) and
the absorption of the resonance radiation of the
ISO 835-2:1981 B Laboratory glassware - Graduated
aluminium/silicon measured and compared with that
pipettes - Part 2: Pipettes for which no waiting time
is specified. of Standard calibration solutions.

8 g of sodium hydroxide in a zirconium crucible fitted
4 Reagents
with a close-fitting lid (5.2) at dull red heat until a clear
melt is obtained. Cool and dissolve the solidified melt
During the analysis, use only reagents of recognized
in 100 ml of hydrochloric acid/water Solution (4.6.2) in
analytical grade and only water of at least grade 3
purity as specified in ISO 3696. a 400 ml beaker (5.12). Cool, transfer and dilute the
Solution quantitatively with water to 1 000 ml in a
volumetric flask (5.8) followed by immediate transfer
4.1 Potassium hydrogensulfate, (KHSO,), fused
to a plastic bottle (5.14) for long-term storage.
solid.
4.2 Flux, mixture of 90 % (m/m) dilithium tetraborate
5 Apparatus
(Li,B,O,) and 10 % (m/m) lithium fluoride (LiF).
Laborstory apparatus and apparatus described in 5.1
4.3 Propan-2-01. to 5.15 shall be used. Clean all glassware carefully
with hot hydrochloric acid (4.6.1) and rinse thoroughly
with water to eliminate contamination.
4.4 Toluene.
4.5 Toluene/propan-2-01 mixture (1 + 1). 5.1 Platinum basin, 100 ml capacity, cleaned with
molten potassium hydrogensulfate (4.1).
Mix one volume of toluene with one volume of
propan-2-01. NOTE 1 The following cleaning technique is rec-
ommended: place 5 g of potassium hydrogensulfate (4.1) in
the basin, heat in a muffle furnace at 550 “C f 25 “C or over
4.6 Hydrochlorit acid, concentrated, 36 %
a Bunsen burner for 5 min. Allow to cool, wash out with
distilled or deionized water and dry.
4.6.1 Hydrochlorit acid Solution (1 + 1).
5.2 Zirconium crucible, with a close-fitting
Mix one volume of hydrochloric acid (4.6) with one
zirconium lid, 30 ml to 50 ml capacity.
volume of water.
4.6.2 Hydrochlorit acid Solution (1 + 2).
5.3 Mixer, non-aerating, high-speed shear type.
Mix one volume of hydrochloric acid (4.6) with two
5.4 Electric oven, capable of being maintained at a
volumes of water.
temperature between 50 “C and 60 “C.
4.7 Tartaric acid.
5.5 Electric muffle furnace, capable of being main-
tained at temperatures of 550 “C * 25 “C and
4.7.1 Tartaric acid/hydrochloric acid Solution.
925 “C & 25 “C, and preferably having apertures at
front and rear to allow passage of a slow, natura1
Dissolve 5 g of tartaric acid in approximately 500 ml
draught of air.
of water acidified with 40 ml of hydrochloric acid
(4.6) and dilute to 1 000 ml with water.
5.6 Electrical hotplate, with or without a magnetic
stirring capability.
4.8 Standard solutions.
5.7 Spectrometers.
4.8.1 Aluminium Standard solutions.
Use either a ready-made commercially available alu-
5.7.1 Inductively coupled Plasma atomic emis-
minium Standard Solution, 1 000 mg/l, or prepare by
sion spectrometer.
dissolving 1,000 g of aluminium metal (wire form,
99,99 % purity) in 50 ml of hydrochloric acid (4.6) with Use either a sequential or simultaneous spec-
gentle heating in a 400 ml beaker (5.12). Cool, transfer trometer, equipped with an ICP torch and RF gener-
and dilute the Solution quantitatively with water to ator to form and sustain the Plasma.
1 000 ml in a volumetric flask (5.8).
5.7.2 Atomic absorption spectrometer.
4.8.2 Silicon Standard solutions.
Use an Instrument with a modulated hollow cathode
Use either a ready-made commercially available sili-
lamp or other Source of modulated resonance radi-
con Standard solution, 1 000 mg/l, or prepare by fus- ation 0% aluminium/silicon; a dinitrogen Oxide (nitrous
ing 2,140 g of Silicon dioxide (99,99 % purity) with oxidejlacetylene burner; and a light detector with a

0 ISO ISO 10478:1994(E)
preferably contain approximately 1,3 mg of alu-
suitable measuring and readout System. The scale
minium.
shall be linear in absorbance or in light intensity, or
shall be directly in concentration units with curve cor-
NOTE 3 The mass of test Portion proposed, based on the
rection.
aluminium content, will also suffice for the Silicon determi-
nation, as both elements are usually found in fuel oils as-
5.8 Volumetric flasks, 100 ml and 1 000 ml, com-
sociated with each other.
plying with ISO 1042, class A.
solution
5.9 Pipettes, 1 ml, 2 ml, 5 ml, 10 ml, 20 ml and 7.2 Preparation of test
25 ml, complying with ISO 648, class A.
7.2.1 lmmediately after homogenization transfer the
test Portion from the homogenized Sample to the
5.10 Pipettes, 1 ml and 2 ml, graduated in 0,l ml
weighed platinum basin (5.1); reweigh the basin and
subdivisions, complying with ISO 835-2.
contents to the nearest 0,l g to obtain the mass of
the test Portion taken.
5.11 Measuring cylinders, 10 ml, 25 ml, 50 ml and
100 ml, with subdivided graduations, complying with
7.2.2 Warm the basin and contents gently with a
ISO 4788.
Bunsen flame until the Sample ignites. Maintain the
contents of the basin at a temperature such that most
5.12 Beaker, 400 ml squat form, complying with
of the combustible material is removed and only car-
ISO 3819.
bon and ash remain.
5.13 Filter Paper, “ashless ”, 0,Ol % (m/m) ash
NOTE 4 If the Sample contains considerable amounts of
maximum.
moisture, foaming and frothing may Cause loss of Sample.
5.14 Plastic bottles, unfilled virgin plastic, suitable
If foaming and frothing occur, discard the Sample and
for long-term storage of dilute acid solutions, 100 ml
to a fresh Portion add 1 ml to 2 ml of propan-2-01
and 1 000 ml.
(4.3) before heating. If foaming and frothing are not
sufficently reduced, add 10 ml of a mixture of
5.15 Balance, capable of being read to the nearest toluene/propan-2-01 (4.5) to a further test Portion and
0,2 mg. mix thoroughly. Place several Strips of ashless filter
Paper (5.13) in the mixture and warm gently (when
the Paper begins to burn, the greater patt of the water
6 Sample preparation
will have been removed).
The Sample shall be homogenized thoroughly before
7.2.3 Place the basin and contents in the muffle
the test Portion is taken. Place the Sample Container
furnace (5.5) preheated to a temperature of
in an oven at a temperature between 50 “C and
550 “C & 25 “C. Maintain the muffle furnace at this
60 “C and maintain the Sample at this temperature
temperature until all the carbon has been removed
until all the Sample has melted and reached a uniform
viscosity. Insert the shaft of the mixer (5.3) into the and only ash remains.
Sample so that the head of the shaft is immersed to
NOTE 5 This may require heating overnight.
approximately 5 mm from the base of the Container.
Homogenize the Sample for approximately 5 min. In
7.2.4 Cool the basin to room temperature and to the
the case of fluid samples which have stood undis-
contents of the basin add 0,4 g of the flux (4.2) and
turbed for several months, use a plastic rod to dis-
mix it with the ash. Place the basin and contents for
lodge any Sediment adhering to the base of the
5 min in a muffle furnace preheated to a temperature
Sample Container before homogenization.
of 925 “C ~f 25 “C. Remove the basin and ensure
NOTE 2 Failure to use this homogenization procedure
contact of the flux with the ash. Replace the basin in
wili invalidate results.
the muffle furnace and maintain at a temperature of
925 “C + 25 “C for a further 10 min.
7 Procedure
7.2.5 Remove the basin, cool the fusion melt to
room temperature and add 50 ml of tartaric
7.1 Test Portion
acid/hydrochloric acid Solution (4.7.1) to the basin.
Place the basin and contents on a hotplate (5.6) and
The mass of test Portion taken from the Sample
maintain at a moderate temperature without boiling.
(clause 6) shall weigh between 20 g and 50 g, and
0 ISO
NOTES
The calibration solutions then contain 5 mg/l,
10 mg/l, 25 mg/1 and 50 mg/1 of Silicon respectively.
6 Excessive evaporatio n of the solutio n could lead to pre-
cipitation of an insoluble form of silica.
7.4.3 Storage
7 Prolonged heating may be required to dissolve the
Transfer all Standards to 100 ml plastic bottles (5.14).
solidified melt completely and obtain a Solution. Agitation
or the use of magnetic stirring may be employed to Speed
NOTE 9 When both aluminium and Silicon are being de-
dissolution of the solidified melt.
termined together, the 5 mg/1 to 50 mg/1 calibration sol-
utions of each may be combined, providing there are no
7.2.6 Allow the Solution to cool and transfer it to t
...