ISO 22241-2:2006

INTERNATIONAL ISO
STANDARD 22241-2
First edition
2006-10-15

Diesel engines — NOx reduction agent
AUS 32 —
Part 2:
Test methods
Moteurs diesel — Agent AUS 32 de réduction des NOx —
Partie 2: Méthodes d'essai




Reference number
ISO 22241-2:2006(E)
©
ISO 2006

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ISO 22241-2:2006(E)
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ISO 22241-2:2006(E)
Contents Page
Foreword. iv
1 Scope . 1
2 Normative references . 1
3 Specifications. 1
4 Sampling. 1
5 Precision and dispute. 2
Annex A (normative) Sampling. 3
Annex B (normative) Determination of urea content by total nitrogen . 5
Annex C (normative) Refractive index and determination of urea content by refractive index. 9
Annex D (normative) Determination of alkalinity. 13
Annex E (normative) Determination of biuret content . 16
Annex F (normative) Determination of aldehyde content. 21
Annex G (normative) Determination of insoluble matter content by gravimetric method . 25
Annex H (normative) Determination of phosphate content by photometric method. 28
Annex I (normative) Determination of trace element content (Al, Ca, Cr, Cu, Fe, K, Mg, Na, Ni, Zn)
by ICP-OES method. 34
Annex J (normative) Determination of identity by FTIR spectrometry method. 40
Annex K (informative) Precision of test methods . 42
Bibliography . 43

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ISO 22241-2:2006(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 22241-2 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 5, Engine
tests.
This first edition cancels and replaces ISO/PAS 22241-2:2005, which has been technically revised.
ISO 22241 consists of the following parts, under the general title Diesel engines — NOx reduction agent
AUS 32:
⎯ Part 1: Quality requirements
⎯ Part 2: Test methods
The following parts are under preparation:
⎯ Part 3: Packaging, transportation and storage
⎯ Part 4: Refilling interface
Annexes A to J form a normative part of this International Standard. Annex K is for information only.

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INTERNATIONAL STANDARD ISO 22241-2:2006(E)

Diesel engines — NOx reduction agent AUS 32 —
Part 2:
Test methods
1 Scope
This part of ISO 22241 specifies test methods required for determination of the quality characteristics of the
NOx reduction agent AUS 32 (aqueous urea solution) specified in ISO 22241-1.
In the remaining parts of ISO 22241, the term “NOx reduction agent AUS 32” will be abbreviated to “AUS 32”.
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 22241-1, Diesel engines — NOx reduction agent AUS 32 — Part 1: Quality requirements
ISO 3675, Crude petroleum and liquid petroleum products — Laboratory determination of density —
Hydrometer method
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 4259, Petroleum products — Determination and application of precision data in relation to methods of test
ISO 12185, Crude petroleum and petroleum products — Determination of density — Oscillating U-tube
method
3 Specifications
Compliance with the limits specified in Table 1 of ISO 22241-1 shall be determined by the test methods
specified in Annexes B through J of this part of ISO 22241.
Determination of the density shall be conducted in accordance with ISO 3675 or ISO 12185.
NOTE For the purposes of this International Standard, the terms “% (m/m)” and “% (V/V)” are used to represent the
mass fraction and the volume fraction of a material respectively.
4 Sampling
Samples shall be taken in accordance with Annex A.
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ISO 22241-2:2006(E)
5 Precision and dispute
5.1 General
All test methods referred to in this part of ISO 22241 include a precision statement according to ISO 4259. In
cases of dispute, the procedures described in ISO 4259 shall be used for resolving the dispute, and
interpretation of the results based on the test method precision shall be used.
The precision of the test method, as determined by statistical examination in accordance with ISO 4259, is
specified in each annex. Additionally, this information is summarized in Annex K for all test methods for the
convenience of the user of this part of ISO 22241.
The statistical significance of the precision quoted in this part of ISO 22241 is generically defined in 5.2 and
5.3, in which the “xx (unit)” stands for the repeatability and reproducibility in question.
5.2 Repeatability, r
The difference between two test results obtained by the same operator with the same apparatus under
constant operating conditions on identical test material would, in the long run, in the normal and correct
operation of the test method, exceed xx (unit) in only one case in 20.
5.3 Reproducibility, R
The difference between two single and independent test results obtained by different operators working in
different laboratories on identical test material would, in the long run, in the normal and correct operation of
the test method, exceed xx (unit) in only one case in 20.
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ISO 22241-2:2006(E)
Annex A
(normative)

Sampling
A.1 General
The sampling method specified in this annex is valid for each sampling of AUS 32 throughout the supply chain
after the shipment from the manufacturer’s site to the AUS 32 containers of the vehicles.
A.2 Principle
The limits for the quality characteristics of AUS 32, which are specified in ISO 22241-1, are the representative
analytical results that can only be obtained when the sample is protected from any contamination before the
analysis.
Therefore, suitable bottles shall be used for sampling, which do not contaminate the sample, especially
regarding the trace elements, and which minimize the risk of algae or bacteria growth.
NOTE The sampling method specified in this annex is based on ISO 5667-2 and ISO 5667-3.
A.3 Possible contaminants
During the sampling process, foreign matter may lead to contamination of the sample. Under realistic
conditions, the following sources of contamination will pose a major hazard:
⎯ residues of process aids used for the production of the sampling bottles;
⎯ contaminants which have been deposited in the empty bottles during the time they are stored empty;
⎯ contaminants from the air, i.e. dust or any foreign matter from the surrounding, during the sampling;
⎯ residues of cleaning agents, which have been used for cleaning the sampling equipment and the bottles
as well;
⎯ fuel.
A.4 Apparatus
A.4.1 Sampling bottles
1000-ml wide neck bottles shall be used. Suited materials for these bottles are HD-polyethylene,
HD-polypropylene, polyfluorethylene, polyvinylidenedifluoride and tetrafluoroethylene-perfluoroalky vinyl ether
copolymer (PFA). In case of dispute, PFA bottles should be used.
Prior to the first use with AUS 32, the bottles shall be cleaned and finally rinsed with de-ionized water followed
by AUS 32.
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ISO 22241-2:2006(E)
A.4.2 Labels
Each bottle shall be labelled using labels of approximately 10 cm × 5 cm. The labels and the writing on these
labels shall be resistant to water and to AUS 32.
A.5 Sampling
The locked wide-neck bottle shall be opened, the cap shall be put down on a clean surface with the opening
turned downward. After flushing the sampling pipe, the bottle shall be filled completely with AUS 32 from the
container. The first filling shall be discarded, and the bottle shall immediately be re-filled with AUS 32 and
closed tightly. The label shall be attached to the bottle (see A.4.2). During the filling of the sample, maximum
care shall be taken that neither dust nor liquid pollutants get into the bottle.
The filled bottle should reach the laboratory as soon as possible. During transportation and storage, the
sample should be kept at the lowest possible temperature, preferably between 0 °C and 15 °C, and kept away
from daylight to prevent growth of algae.
It is recommended to conduct the analysis within three weeks in order to take into account possible changes
in the ammonia content.
A.6 Sample quantity
The minimum quantity of sample material depends on the type of analysis conducted. Whenever possible,
make sure that a sufficient volume of sample material is available (recommendation: 1 litre), and at least
double that which is required for complete verification of AUS 32 specifications. In case of dispute, a sufficient
number of samples shall be taken according to ISO 4259.
A.7 Labelling
The label should contain the following information:
⎯ product name;
1)
⎯ name of the company which owns the sample product ;
1)
⎯ address where the sample was taken from ;
1)
⎯ manufacturer of the sample product ;
⎯ batch or lot number;
1)
⎯ container from which the sample was taken ;
1)
⎯ part of the container where the sample was taken from (sampling point) ;
1)
⎯ date and time of sampling ;
1)
⎯ sample shipment date ;
1)
⎯ name and signature of the person who took the sample .

1) Mandatory only in cases of dispute.
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ISO 22241-2:2006(E)
Annex B
(normative)

Determination of urea content by total nitrogen
B.1 General
This annex specifies the procedure for determining the urea content of AUS 32.
The method is applicable for the determination of the urea content in the range from 30 % to 35 % (m/m).
B.2 Principle
The sample is combusted at high temperatures in a stream of oxygen. Following the reduction of formed
nitrogen oxides to elemental nitrogen and removal of any interfering products of combustion, nitrogen is
measured with a thermal-conductivity detector. The urea content is calculated from the determined total
nitrogen minus the nitrogen content of biuret.
B.3 Apparatus
B.3.1 Automatic nitrogen analyser, based on combustion methods.
B.3.2 Analytical balance.
The accuracy of the balance is a function of the analyser used and the required weighed portions. Resolution
should be 0,1 % or better of the weighed portion.
B.3.3 Auxiliary devices for sample preparation, for example:
⎯ tweezers with a blunt tip;
⎯ micro-spatula with a flattened tip;
⎯ pipette.
The pipette is recommended for weighing in and thus does not need to be calibrated. It is important, however,
to obtain a good droplet size (small droplets). Fixed-volume pipettes or pipettes with an adjustable volume in
the range from 10 µl to 1 000 µl or single-trip Pasteur pipettes with a fine tip may also be used.
B.3.4 Customary chemically resistant glass.
B.4 Chemicals
B.4.1 De-ionized water, conductivity less than 0,1 mS/m, according to ISO 3696 grade 2.
B.4.2 Auxiliary combustion agent and other equipments, appropriate for use with the selected nitrogen
analyser.
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ISO 22241-2:2006(E)
The following materials are merely examples. Other or similar materials may be used as required, depending
on the system that is available:
⎯ tin capsule or similar sample containers;
⎯ auxiliary combustion agent, non-nitrogenous, such as saccharose, cellulose;
⎯ absorbing agent for liquids, non-nitrogenous, such as magnesium oxide.
B.4.3 Standard substances for nitrogen determination, preferably with certified nitrogen content.
EXAMPLE Suitable standard substances include: ethylenediamine tetraacetic acid (EDTA), nicotinic acid amide.
Low-biuret urea of adequate purity (for example crystalline ultra pure or analytical) or other such standard
substances recommended by and available from the equipment manufacturer may also be used. Certified
standard substances should be preferred.
NOTE Liquid standard substances (e.g. urea solutions) are not suited for calibration purposes.
B.4.4 Oxygen, min. 99,995 % O .
2
B.4.5 Other ultrapure gases, if required to operate the nitrogen analyser, such as helium, min. 99,996 % He.
B.4.6 Other reagents or auxiliary agents, as required by the equipment.
B.5 Procedure
B.5.1 General
The sample should be fully dissolved and free from urea crystals. It may be heated to max. 40 °C as required
prior to further processing.
NOTE Different types of apparatus are available on the market. The resulting various resources and modes of
operation are not an object of this part of ISO 22241. Rather, operation should be based on the respective operation
manuals.
B.5.2 Reference curve
Perform calibration as required for the specific type of analyser and according to the respective operation
manuals (for example, after replacement of the combustion tube, reagent or similar) by performing
measurements as described in B.5.4. Weigh in an appropriate amount of standard substances repeatedly as
appropriate for the respective types of apparatus to obtain a reference curve.
B.5.3 Inspecting the apparatus for good working order, and the reference curve
Use an appropriate standard substance to review the good working order of the apparatus and the reference
curve. Preferably, a certified urea standard solution should be used.
Frequency of inspection is a function of the analyser used.
B.5.4 Measurement
Weigh a portion of the sample in a suitable holder (such as a tin capsule) as specified for the type of nitrogen
analyser used. The amount should be such that the absolute amount of nitrogen is in the middle range of the
reference curve.
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ISO 22241-2:2006(E)
Use approximately the three-fold amount of combustion agent (for example, non-nitrogenous cellulose), and
additional binders (for example, magnesium oxide) as required.
When using liquid feeder systems, the volume used should be no less than 100 µl. The sample mass is
calculated using the density that was calculated according to ISO 12185.
Enter the required data (weighed portion, sample identification) into the analyser (or a control computer)
depending on the type of apparatus. Feed the weighed-in sample to the analyser, and start combustion.
Perform at least three (3) single determinations.
B.6 Results
B.6.1 Calculation
Prior to calculating the reference curve, drift of the baseline or samples, determine the blank reading value by
means of blank samples, and use this value to correct the respective analytical sequences.
Use the apparatus-specific programme to calculate the reference curve or the drift correction for the samples.
Calculate the mean value for the samples. If there is a strong dispersion of single values (relative standard
deviation RSD > 1,0 %), repeat the affected sample. After that, determine the mean value for this sample from
all single values.
Determine the urea content from the mean value from at least three nitrogen determinations:
ww=×2,1438 −F×w
( )
UN Bi
where
w is the urea content [% (m/m)];
U
w is the mean value of the nitrogen content [% (m/m)] (to the nearest 0,01%);
N
w is the mean value of the biuret content (%), determined according to Annex E;
Bi
F is the factor for converting the biuret content to nitrogen (0,407 6).
B.6.2 Expression of results
The result is the arithmetic mean value from at least three (3) single determinations (nitrogen determinations).
Round off the result of the urea content calculation to the nearest 0,1 %.
B.7 Precision
See 5.2, 5.3 and Table B.1.
Table B.1 — Precision
Urea content Repeatability Reproducibility
w r R
U
% (m/m) % (m/m) % (m/m)
30 to 35 0,4 1,0
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ISO 22241-2:2006(E)
B.8 Test report
The report shall include the following data as a minimum requirement:
a) type and description of tested product;
b) reference to this part of ISO 22241;
c) sampling method used;
d) test result (see B.6);
e) deviations from the specified mode of operation, if any; and
f) test date.
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ISO 22241-2:2006(E)
Annex C
(normative)

Refractive index and determination of urea content by refractive index
C.1 General
This annex specifies the procedure for the determination of the refractive index of AUS 32. The test method is
applicable to liquids having refractive indices in the range of 1,33 to 1,39 and at temperatures of 20 °C to
30 °C.
Based on the measurement of refractive index, the method shall be used for determining the content of urea in
the range of 30 % to 35 % (m/m).
C.2 Principle
Measurement is based on the dependence of refractive index on the concentration of urea in an aqueous
solution at a definite temperature.
The content is determined by means of a reference curve.
NOTE The method specified in this annex is based on ISO 5661.
C.3 Apparatus
C.3.1 Refractometer, measuring range 1,330 00 to 1,390 00, resolution 0,000 01.
C.3.2 Analytical balance, resolution 0,1 mg or better.
C.3.3 Thermostat, temperature-control precision 0,02 °C.
C.3.4 Drying oven.
C.3.5 150 ml beaker, tall form.
C.3.6 Typical laboratory glass.
C.4 Chemicals
C.4.1 De-ionized water, conductivity less than 0,5 mS/m according to ISO 3696 grade 3.
C.4.2 Urea, crystalline, with biuret content less than 0,1 % (m/m).
Prior to weighing the urea to draw the reference curve, it shall be dried for 2 h at 105 °C.
C.4.3 Urea test solution, 32,5 % (m/m).
The test solution shall be made by exactly weighing urea and water. The desired value and the permissible
dispersion shall be established through 10 measurements.
The solution shall be kept air-tight in the refrigerator and should be used within 4 weeks maximum.
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ISO 22241-2:2006(E)
C.5 Procedure
C.5.1 General
The sample should be fully dissolved and free from urea crystals. It may be heated to u 40 °C as required
prior to further processing.
NOTE Different types of apparatus are available on the market. The resulting various resources and modes of operation
are not an object of this part of ISO 22241. Rather, operation should be based on the respective operation manuals.
C.5.2 Drawing the reference curve and determining the evaluation factor
The following urea solutions shall be prepared by weighing urea in glass beakers and then adding the
corresponding quantity of de-ionized water: 30,0 % (m/m) / 31,5 % (m/m) / 32,5 % (m/m) / 33,5 % (m/m) /
35,0 % (m/m).
The refractive index of these solutions shall be determined at 20 °C ± 0,02 °C.
The diagram shall show a stringent linear relationship between the refractive index and concentration.
An evaluation factor shall be calculated from the urea concentrations and the refractive indices:
5
w
∑ U,i
i=1
F=
5
nn−
()
∑ U,i W
i=1
where
F is the evaluation factor (%);
w is the urea content of the i-th reference solution [%(m/m)];
U,i
n is the refractive index of the i-th reference solution;
U,i
n is the refractive index of water and is 1,332 96 when measured with a refractometer of five-decimal
W
resolution.
C.5.3 Checking the instrument function and the reference curve
The instrument function shall be checked weekly using water or a reference standard. If a greater deviation
from desired value than 0,000 02 occurs, adjust the instrument according to the instructions provided by the
manufacturer. If afterwards the desired value is not attained, then the instrument shall be disabled for further
measurements and the manufacturer’s service should be called for.
Adjust the thermostat to the desired temperature, reading this temperature on the refractometer thermometer
on the discharge side. Maintain the flow of water so that the desired temperature shall be reached and
maintained within ± 0,02 °C.
Furthermore, the reference curve shall be verified weekly with urea solution [32,5 % (m/m)]. In the process, the
refractive index shall be determined and the concentration shall be calculated with the help of the factor
according to C.6. If the concentration determined deviates from the desired value by more than 0,1 % (m/m), a
new test solution shall used. If the deviation persists, the reference curve shall be created anew.
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ISO 22241-2:2006(E)
C.5.4 Sample preparation and measuring
The original sample shall be measured at 20 °C ± 0,02 °C without further preparation.
Measure the urea content two times with different test portions. Should the difference between the separate
values be more than 0,000 05, the measurements shall be repeated.
C.6 Results
C.6.1 Calculation
Urea content shall be calculated according to the following equation:
wn=−n ×F−w
( )
UP W Bi
where
w is the urea content [% (m/m)];
U
n is the refractive index of sample (with 5 decimals);
P
n is the refractive index of water (with 5 decimals);
W
F is the evaluation factor (%);
w is the biuret content of the solution [% (m/m)];
Bi
(determined according to Annex E; biuret has the same refractive index as urea).
C.6.2 Expression of results
The result is defined as the arithmetic mean of two single measurements. Round off the result of the refractive
index to four decimals. Round off the result of the urea content calculation to the nearest 0,1 % (m/m).
C.7 Precision
See 5.2, 5.3 and Table C.1.
Table C.1 — Precision
Characteristics Repeatability Reproducibility
r R
Refractive index n
P
0,000 1 0,001 0
1,33 to 1,39
Urea content w
U
0,1 % (m/m) 1,0 % (m/m)
30 % to 35 % (m/m)
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ISO 22241-2:2006(E)
C.8 Test report
The report shall include the following data as a minimum requirement:
a) type and description of tested product;
b) reference to this part of ISO 22241;
c) sampling method used;
d) test result (see C.6);
e) deviations from the specified mode of operation, if any; and
f) test date.
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ISO 22241-2:2006(E)
Annex D
(normative)

Determination of alkalinity
D.1 General
This annex specifies the procedure for the determination of the alkalinity of AUS 32, calculated as ammonia,
in the range 0,1 % to 0,5 % (m/m).
D.2 Principle
The measurement is based on potentiometric titration of free ammonia of a test portion with a standard
volumetric hydrochloric acid solution to the endpoint at pH = 5,7.
D.3 Apparatus
D.3.1 Analytical balance, resolution 0,1 mg or better.
D.3.2 Automatic burette.
D.3.3 Potentiometer, capable of measuring with a precision of 0,01 pH units, equipped with glass
combined pH-electrode.
D.3.4 Magnetic stirrer.
D.3.5 Beaker, 150 ml, tall shaped.
D.3.6 Measuring cylinder, 100 ml.
D.4 Chemicals
D.4.1 General.
During the analysis, use only reagents of recognized analytical grade and only distilled or de-ionized water of
an electric conductivity lower than 0,5 mS/m, according to ISO 3696 grade 3.
D.4.2 Hydrochloric acid.
This is 0,01 mol/l standard solution.
D.4.3 Buffer solutions.
The following standard buffer solutions shall be used for the determination of alkalinity:
⎯ standard buffer solution, pH = 4,008;
⎯ standard buffer solution, pH = 9,184;
⎯ standard buffer solution, pH = 8,00.
NOTE Such solutions are commercially available.
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ISO 22241-2:2006(E)
D.5 Procedure
D.5.1 Interferences
The samples of AUS 32 taken shall be stored and shipped at a temperature not higher than 25 °C in order to
avoid ammonia formation.
The containers shall be closed tightly and the analysis time shall not be protracted by interruption to avoid
evaporation of ammonia.
D.5.2 Check of potentiometric system
The correct function of the potentiometric system shall be checked by use of the standard buffer solutions at
pH = 4,008 and pH = 9,180.
The standard buffer solution at pH = 8,00 shall be used for daily check of the potentiometric system.
D.5.3 Preliminary test
Weigh about 1 g of the homogenous sample to 0,05 g (sample mass m ) and put it into a 150 ml beaker filled
S
with about 100 ml distilled or de-ionized water.
Titrate with the hydrochloric acid solution (0,01 mol/l) under stirring to the endpoint at pH = 5,7.
Calculate the content of ammonia.
Depending on the content of alkalinity found, weigh the following sample portions for the determination:
⎯ alkalinity content found by the preliminary test [% (m/m)]: 0,02 0,05 0,1 0,2 to 0,5
⎯ mass of test portion for the determination (g): 10 5 2 1
⎯ see D.6.1 for example.
D.5.4 Determination
Weigh the mass of the homogenous sample to 0,05 g found by the preliminary test (sample mass m ) and put
S
it into a 150 ml beaker filled with about 100 ml dis
...