EN ISO 10058:1996

SLOVENSKI STANDARD
SIST EN ISO 10058:1998
01-april-1998
Magneziti in dolomiti - Kemijska analiza (ISO 10058:1992)
Magnesites and dolomites - Chemical analysis (ISO 10058:1992)
Magnesit und Dolomit - Chemische Analyse (ISO 10058:1992)
Produits de magnésie et de dolomie - Analyse chimique (ISO 10058:1992)
Ta slovenski standard je istoveten z: EN ISO 10058:1996
ICS:
71.040.40 Kemijska analiza Chemical analysis
73.080 Nekovinske rudnine Non-metalliferous minerals
SIST EN ISO 10058:1998 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 10058:1998

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SIST EN ISO 10058:1998

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SIST EN ISO 10058:1998

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SIST EN ISO 10058:1998
Is0
INTERNATIONAL
STANDARD 10058
First edition
1992-06-l 5
Magnesites and dolomites - Chemical analysis
Produits de magksie et de dolomie - Analyse chimique
Reference number
IS0 10058: 1992(E)

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SIST EN ISO 10058:1998
IS0 10058:1992(E)
Contents
Page
1
1 Scope .s. . . . . . . . . . . . . . . . . .I. . . . . . . .e. .,.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Dissolution and determination of silica
4
3 Determination of alumina . . . . . . . . . .I.” . . . . . . . . . . .d.“.u”.am.
..wI..... 6
4 Determination of total iron calculated as iron(lll) oxide
Determination of titanium(W) oxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .* 7
5
9
6 Determination of manganese(lV) oxide .
IO
7 Determination of chromium(lII) oxide .
12
8 Determination of calcium oxide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Determination of magnesium oxide . . 13
9
. . . . 15
IO Determination of potassium, sodium and lithium oxides
16
11 Determination of the loss on ignition . . . . . . . . . . . . . . . . . . .“.
16
12 Test report .-.,.
Annex
17
. . . . . . . . . . . . . . . . . . . . .
A Determination of boron content of magnesites
0 IS0 1992
All rights reserved. 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 the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
ii

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SIST EN ISO 10058:1998
IS0 10058:1992(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
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, govern-
mental and non-governmental, in liaison with ISO, also take part in the
work. IS0 collaborates closely with the International Electrotechnical
Commission (IEC) 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 Inter-
national Standard requires approval by at least 75 % of the member
bodies casting a vote.
International Standard IS0 10058 was prepared by Technical Committee
ISO/TC 33, Refractories, Sub-Committee SC 2, Methods of testing.
Annex A forms an integral part of this International Standard.
. . .
III

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SIST EN ISO 10058:1998
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SIST EN ISO 10058:1998
INTERNATIONAL STANDARD IS0 10058:1992(E)
Magnesites and dolomites - Chemical analysis
2.2 Reagents
1 Scope
During the analysis, unless otherwise stated, use
This International Standard specifies methods for
only reagents of recognized analytical grade and
the determination of silica, alumina, titania, iron ox-
only distilled water or water of equivalent purity.
ide and oxides of manganese, chromium, calcium,
magnesium, sodium, potassium and lithium. It also
2.2.1 Sodium carbonate, anhydrous.
specifies methods for determining the loss on ig-
nition of magnesite and dolomite, and of refractories
2.2.2 Boric acid, powdered.
based on these raw materials.
Annex A describes a method for the determination
2.2.3 Polyethylene oxide solution, 2,5 g/l.
of the boron content of magnesites only.
Add 0,5 g of polyethylene oxide to 200 ml of water
NOTE 1 Physical methods are used increasingly for while stirring slowly, preferably with a mechanical
chemical analysis. At present, it is not possible to de-
stirrer, until dissolved. Discard after 2 weeks.
scribe a standardized test method, because the type of
apparatus used is important.
2.2.4 Accelerator granules, ashless, of mass about
1 g-
2 Dissolution and determination of silica
2.2.5 Hydrochloric acid, concentrated,
= I,19 g/ml.
P
2.1 Principle
2,2.6 Hydrochloric acid, diluted 1 + 19.
Decompose the sample with hydrochloric acid and
Add 1 volume of hydrochloric acid (2.2.5) to 19 vol-
separate the silica by coagulation with a
umes of water.
polyethylene oxide solution. Filter, wash the residue,
heat and weigh it, and submit it to a treatment with
2.2.7 Sulfuric acid, concentrated, p = I,84 g/ml.
hydrofluoric and sulfuric acids. After this treatment,
weigh the remaining residue again and fuse it in
2.2.8 Hydrofluoric acid, 40 % (m/m).
sodium carbonate and boric acid. It is then dissolved
in the filtrate from the silica, and the solution is di-
2.3 Apparatus
luted to a standard volume to obtain the stock sol-
ution (A) of the sample.
Usual laboratory apparatus and the following.
In an aliquot, the small quantity of silica not separ-
2.3.1 Sand bath or hot plate.
ated by coagulation is subsequently determined by
a spectrophotometric method based on the forma-
2.3.2 Muffle furnace, capable of being controlled at
tion of molybdenum blue, using alternatively iron
1 180 OC to 1 200 “C.
sulfate or tin(ll) chloride as a reducing agent. The
absorbance maximum of the reduced silico-
2.3.3 Platinum crucible.
molybdate complex lies at a wavelength of 810 nm.
1

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SIST EN ISO 10058:1998
IS0 10058:1992(E)
2.4 Procedure
2.5 Spectrophotometric determination of
residual silica in filtrate
Weigh into a 250 ml beaker, 5,000 gl) of finely ground
analytical sample dried at 110 “C. Add 25 ml of wa-
2.51 Reduction to molybdenum blue complex with
ter and 40 ml of concentrated hydrochloric acid
iron( I I) sulfate
(2.2.5) and cover with a watch-glass. Transfer to a
sand bath or a hot-plate (2.3.1) and boil for 30 min.
2.5.1 .I Reagents
Allow the beaker and contents to cool, rinse the
watch-glass with water,
add the accelerator
During the analysis, unless otherwise stated, use
granules (2.2.4) and stir to break up the pulp. Then
only reagents of recognized analytical grade and
add, stirring all the time, 5 ml of polyethylene oxide
only distilled water or water of equivalent purity.
solution (2.2.3) and allow to stand for 5 min. Filter
the solution through a closed-pore paper filter suit-
able for separating very fine precipitates. Transfer
2.5.1 .I .I Ammonium hydroxide solution,
the residue (containing the precipitate of silica)
= 0,9g/ml.
P
quantitatively with hot diluted hydrochloric acid
Although the method allows for the presence of
(2.2.6) to the filter paper. Wash the precipitate six
silica in the ammonium hydroxide solution, the re-
times with hot diluted hydrochloric acid (2.2.6) and
agent should contain as little silica as possible. It
then with hot water until free from chlorides (up to
should be noted that ammonium hydroxide solution
a volume of about 400 ml). Store the filtrate. Transfer
stored in glass bottles will dissolve silica from the
the filter paper and precipitate to a heated and
glass.
weighed platinum crucible (2.2.3). Heat at a low
temperature until the precipitate is free from
carbonaceous matter, then heat it in the muffle fur-
2.51 .I .2
Ammonium iron(lll) sulfate solution.
nace (2.3.2) controlled at 1 180 “C to 1 200 “C to
Dissolve 100 g of ammonium iron(lll) sulfate
constant mass (m,), a time of 15 min normally being
dodecahydrate [NH,Fe(SO,),~l2H,O] in water, add
sufficient.
300 ml of concentrated hydrochloric acid (2.2.5) and
Moisten the residue in the cold crucible with water,
dilute to 1 litre with water.
add 5 drops of concentrated sulfuric acid (2.2.7) and
IO ml of hydrofluoric acid (2.2.8). Evaporate to
2.5.1 .I .3 Ammonium molybdate solution.
dryness in the sand bath or on the hot-plate in a
fume cupboard.
Dissolve 80 g of hexammonium heptamolybdate
tetrahydrate [(NH,),Mo,0Zd.4H,0] in water, filter if
Heat the crucible and the residue, cautiously at first
necessary, dilute to 1 litre and mix. Store in a
over a Bunsen burner, and finally for 5 min between
polyethylene bottle. Renew the solution after 4
1 180 “C and I 200 “C in the muffle furnace. Allow to
weeks, or earlier if any appreciable deposit is ob-
cool in a desiccator and weigh (mass IYQ). If the
served.
residue weighs more than 30 mg, repeat the treat-
ment with hydrofluoric and sulfuric acids to ensure
2.5.1 .I .4 Oxalic acid solution.
that all the silica is removed. The difference be-
tween the two masses (m, - m2) represents the
Dissolve
100 g of oxalic acid dihydrate
“gravimetric” silica.
(C,H,0d.2H,0) with water and dilute to 1 Iitre.
Fuse the residue from the hydrofluoric and sulfuric
acid treatment with 2 g of the anhydrous powdered 2.5,l .I .5 Iron sulfate solution.
sodium carbonate (2.2.1) and 0,7 g of powdered
Dissolve IO g of iron sulfate heptahydrate
boric acid (2.2.2). Allow the melt to cool and dissolve
(FeSO,e7H,O) in water, add 4 drops of diluted sulfuric
in the filtrate from the main silica. Cool, transfer the
acid (1 + 1) and dilute to 100 ml with water. Prepare
solution to a 500 ml one-mark volumetric flask, di-
this solution freshly before use.
lute to volume with water and mix.
This solution will become stock solution A of the
2.5.1.1.6 Silica stock solution, containing 0,5 g of
sample for the spectrophotometric determination of
SiO, per litre.
the residual silica in accordance with 2.5.1 or 2.5.2
and for the determination of alumina (clause 3) Ignite a sample of high purity silica to 1 000 “C and
iron(lll) oxide (clause 4), titanium(lV) oxide
cool. Then weigh 0,250 g of this sample in a platinum
(clause 5), manganese(lV)
oxide (clause S), crucible with 5 g of anhydrous sodium carbonate.
chromium(lII) oxide (clause 7), calcium oxide
Dissolve the melt in a polyethylene vessel in 300 ml
(clause 8) and magnesium oxide (clause 9).
of water while adding 20 g of sodium hydroxide.
1) In the case of natural iron and silica-rich magnesite, the sample mass may optionally be reduced to 2,000 g. The aliquots
to be taken for the determination are to be changed accordingly.
2

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SIST EN ISO 10058:1998
IS0 10058:1992(E)
Cool the solution to 20 OC, transfer to a 500 ml one- (2.5.1.3.1). Subtract the absorbance of the blank sol-
mark volumetric flask and make up to the mark with ution from that of the sample solution.
water. Stir thoroughly and transfer to a polyethylene
flask for storage. This solution will remain stable for
2.5.1.3.3 The blank solution is treated and meas-
6 months.
ured in the same manner as the sample. Subtract
the absorbance of the blank solution from that of the
1 ml of this standard solution contains 0,5 mg of
sample solution.
SiO,.
2.5.1.1.7 Silica standard solution, containing 0,02 g
2.5.1.4 Plotting the calibration graph.
of SiO, per litre.
Pipette 0 ml, 2 ml, 4 ml, 6 ml, 8 ml and 10 ml vol-
Dilute 20 ml of the silica stock solution (2.5.1.1.6) to
umes of the silica standard solution (2.5.1.1.7) into
500 ml with water in a one-mark volumetric flask.
six 100 ml one-mark volumetric flasks.
Prepare this solution daily if required.
Add one drop of the phenolphthalein solution
1 ml of this standard solution contains 0,02 mg of
(2.5.1.1.8) to the contents of each flask and while
SiO,.
stirring constantly, mix with hydrochloric acid
(1 + 4) until the red colour disappears. Then add the
2.51 .I .8 Phenolphthalein solution.
ammonium hydroxide solution (2.5.1 .I .I) drop by
Dissolve 100 g of phenolphthalein in ethanol and di- drop. As soon as the alkaline reaction produces a
lute to 100 ml. red colour, immediately mix with 5 ml of the am-
monium iron(lll) sulfate solution (2.5.1.1.2) and 5 ml
of the ammonium molybdate solution (2.5.1.1.3), and
2.5.1.2 Apparatus
allow to stand for 20 min. Add 20 ml of the oxalic
acid solution (2.5.1.1.4) and shake the solution until
Usual laboratory apparatus and a spectro-
it becomes clear. Add 1 ml of the iron sulfate
photometer, fitted with cells of an appropriate size.
solution (2.5.1.1.5) and make up to the mark with
water.
2.5.1.3 Procedure
Measure the absorbance of each calibration solution
2.5.1.3.1 Pipette two 5 mE aliquots of the stock sol-
maintained at 20 “C + 2 “C using the spectro-
ution A, prepared as in 2.4, into two 100 ml one-mark
photometer set at an optimum wavelength of
volumetric flasks. Add one drop of phenolphthalein
810 nm against the zero member of the set of cali-
solution (2.5.1.1.8) to each flask, and while continu-
bration solutions as a reference.
ally shaking, add ammonium hydroxide solution
(2.5.1.1.1) one drop at a time. As soon as the alkaline
Use the values thus obtained to plot a calibration
reaction produces a red colour, immediately add
graph. On the basis of this graph, determine the
5 ml of ammonium iron(lll) sulfate solution
mass of silica contained in 5 ml of the stock solution
(2.5.1.1.2). To the first of the two solutions, add 5 ml
A.
of ammonium molybdate solution (2.5.1.1.3) and
leave to stand for 20 min.
2.5.1.5 Expression of results
NOTE 2 Cloudiness may occur but it does not cause any
interference and disappears after the addition of oxalic
The silica content, w(SiO,), expressed as a percent-
acid.
age by mass, is given by the following formula:
Add 20 ml of oxalic acid solution (2.5.1.1.4) and
( ml - m2> + @?3 - m4)
w(Si0,) = X 100
shake the solution until it is clear. Add 1 ml of iron
mo
sulfate solution and make up to the mark with water.
Take the second 5 ml aliquot part of the stock sol-
where
ution A (see 2.4) which will serve as a reference, add
is the mass, in grams, of the test portion;
20 ml of oxalic acid solution to it and leave it also to
stand for 20 min. Add 5 ml of ammonium molybdate
is the mass, in grams, of the crucible and
ml
solution, then 1 ml of iron sulfate solution and
its contents before treatment with
make up to the mark with water. Carry out a blank
hydrofluoric and sulfuric acids;
determination on a solution containing all the re-
agents, but omitting the stock solution (see 2.4).
is the mass, in grams, of the crucible with
m2
the residue after treatment with
2.5.1.3.2 Measure, in cells of an appropriate size,
hydrofluoric and sulfuric acids;
the absorbance
of the solution brought to
20 “C $- 2 OC, using the optimum wavelength of is the mass, in grams, of silica contained
e3
810 nm, and compare it with the reference solution in 5 ml of the stock solution A;
3

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SIST EN ISO 10058:1998
IS0 10058:1992(E)
is the mass, in grams, of silica found in
m4
ml silica standard solution
the blank test solution.
(2.5.1.1.7)
lo /?1416/81101
ml distilled water
110181614121 O I I
2.5.2 Reduction to molybdenum blue complex by
tin( I I) chloride
Add to each flask, while shaking, 5 ml of dilute
hydrochloric acid (1 + 4) and 6 ml of ammonium
2.5.2.1 Reagents, (additional to 2.5.1) molybdate solution (2.5.1.1.3) and allow to stand for
5 min to 10 min at 20 “C to 30 “C. Then add 45 ml of
dilute hydrochloric acid (1 + 1) while shaking and
2.5.2.1 .I 2,4=Dinitrophenol solution.
leave to stand for a further 10 min. After adding
10 ml of tin(ll) chloride solution, fill up to 100 ml and
Dissolve 0,l g of 2,4-dinitrophenol in hot water, di-
mix thoroughly.
lute to 100 ml, cool and filter.
Measure the absorbances of the solutions with ad-
ditions of silica against the zero solution. Use suit-
2.5.2.1.2 Tin(H) chloride solution.
able equipment and the wavelength of 810 nm
(optimum) . The colour will remain stable for 5 min
Dissolve 1 g of tin(ll) chloride in I,5 ml of
to 10 min after adding tin(ll) chloride solution.
hydrochloric acid (2.2.5) cool and dilute to 100 ml.
Prepare a fresh solution when required.
2.5.2.4 Calculation
Calculate “gravimetric” silica from using the differ-
2.5.2.2 Procedure
ence between the masses m, and m2 obtained ac-
cording to 2.4. Calculate the total silica content by
Pipette 5 ml of stock solution A, obtained as in 2.4,
adding the silica remaining in the stock solution A
into a 100 ml volumetric flask (A). Add 15 ml of water
to the “gravimetric” silica.
of the dinitrophenol solution
and two drops
(2.5.2.1.1), then add dilute ammonia solution (1 + 1)
drop by drop until the indicator changes to yellow.
Note the number of drops required. Then add 5 ml 3 Determination of alumina
of dilute hydrochloric acid (1 + 4).
Take a second 100 ml volumetric flask (B), pipette 3.1 Principle
20 ml of water into it and add the same amount of
ammonia solution (1 + 1) as that used for neutraliz-
Dilute an aliquot of stock solution A, prepared as in
ing in flask A. Add two drops of the dinitrophenol
2.4, and take an aliquot from this diluted stock sol-
solution (2.5.2.1.1) and then add dilute hydrochloric
ution. Add 8-hydroxyquinoline solution and buffer
acid (1 + 4) until the indicator changes to colourless.
with ammonium acetate solution. Extract the alu-
Then add 5 ml of dilute hydrochloric acid (1 + 4) in minium oxinate formed by means of chloroform and
excess. measure the extinction of the yellow extract solution.
The absorbance maximum of aluminium oxinate in
Add 6 ml of ammonium molybdate solution
chloroform lies at a wavelength of 390 nm. Under
(2.5.1.1.3) to each volumetric flask (A and B) and al-
these conditions, the Lambert-Beer law is obeyed
low to stand for 5 min to 10 min at 20 “C to 30 “C.
up to a maximum concentration of 0,2 mg AI,O, in
Then add 45 ml of dilute hydrochloric acid (1 + 1)
the measured solution (extract).
and allow to stand for a further 10 min. After adding
10 ml of tin(ll) chloride solution (2.5.2.1.2) make up Iron, forming a black oxinate also soluble in
to 100 ml and mix thoroughly. chloroform, is converted to the iron
phenanthroline complex which does not react with
Measure, in cells of convenient size, the absorbance
oxine.
of the solution in flask A against that of the solution
in flask B using suitable apparatus and an optimum The method is suitable for determination of alumina
wavelength of 810 nm. The colour will remain stable
contents up to 30 O/o. Other elements contained in
for 5 min to 30 min after adding tin(ll) chloride sol- magnesite and dolomite do not interfere with the
ution. determination if they do not exceed the usual con-
centrations. However, when more than 0,2 %
titanium oxide is present, alumina values which are
2.5.2.3 Plotting the calibration graph too high will be found due to extraction of
titanium(lV) oxide, but this is eliminated by com-
Pipette the following volumes into six 100 ml plexing titanium(lV) oxide by addition of hydrogen
peroxide.
volumetric flasks.
4

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SIST EN ISO 10058:1998
IS0 10058:1992(E)
1 %: use 20 ml of diluted stock solution, pre-
3.2 Reagents
pared from the stock solution A;
3.2.1 8-Hydroxyquinoline solution.
2 %: use 10 ml of diluted stock solution, pre-
Dissolve 5 g of 8-hydroxyquinoline (“oxine”) in
pared from the stock solution A;
50 ml of hydrochloric acid (1 volume of hydrochloric
acid (2.2.5) to 1 volume of water), while heating. Af-
5 %: use 5 ml of diluted stock solution, prepared
ter cooling, dilute with water to one litre.
from the stock solution A.
If the alumina content exceeds 5 %, dilute the stock
3.2.2 Thioglycolic acid.
solution so that the concentration of the aliquot to
Mix equal volumes of thioglycolic acid (80 %) and be taken (5 ml or 10 ml) does not exceed
water. Store in a dropper. 0,2 mg AI,O,.
Dilute the aliquot in the separating funnel, if
3.2.3 1 ,lO-Phenanthroline solution.
necessary, to 20 ml with water and add 5 drops of
thioglycolic acid (3.2.2) and 10 ml of
Dissolve 1 g of l,lO-phenanthroline chloride in water
IJO-phenanthroline (3.2.3) solution. Then add in the
and dilute to 250 ml.
following order: 10 ml of 8-hydroxyquinoline solution
NOTE 3 The solution will keep for about 1 week.
(3.2.1), 1 ml of ethylene glycol mono-n-butylether
(3.2.6) and 10 ml of ammonium acetate solution
3.2.4 Ammonium acetate solution. (3.2.4). Shake vigorously for 2 min, after addition of
25 ml of chloroform (from a pipette with automatic
Dissolve 200 g of ammonium acetate in water and
zero adjustment or a burette).
dilute to 1 litre.
After the phase separation, drain off some of the
organic phase to rinse the stop-cock and outlet.
3.2.5 Chloroform.
Then close the stopcock and place a wad loosely in
the outlet tube, to retain drops of water. Rinse again
3.2.6 Ethylene glycol mono-n-butylether.
with some of the extract. Without interruption, run
out the chloroform extract into a dry 1 cm cell and
3.2.7 Sodium hydroxide solution.
cover immediately with a suitable lid. Measure the
absorbance in a spectrophotometer at a wavelength
Dissolve 100 g of sodium hydroxide in water and di-
of 390 nm, using water as a reference solution.
lute to 1 litre.
Make a blank measurement using the reagents
3.2.8 Alumina stock solution (1 mg Al,O,/ml).
and subtract this
without the stock solution,
measurement from the result.
Dissolve 0,529 g of pure metallic aluminium in a
covered polyethylene beaker in 50 ml of sodium hy-
droxide solution. Heat gently if necessary. Then add
3.4 Plotting the calibration graph
100 ml of hydrochloric acid (2.2.5) and heat until the
solution becomes completely clear. Cool to 20 “C
Pipette 0 ml, 5 ml, 10 ml, 15 ml and 20 ml volumes
and dilute with water in a volumetric flask to
of aluminium standard solution (3.2.9) into five
1 000 ml.
100 ml volumetric flasks, and proceed as in 3.3. Use
these results to plot a calibration graph, making the
3.2.9 Aluminium standard solution
necessary corrections for blank solutions (see 3.3).
(0,Ol mg Al,O,/ml).
Dilute 10 ml of the alumina stock solution (3.2.8), af-
3.5 Calculation
ter addition of 25 ml of hydrochloric acid (2.2.5) with
water to 1 000 ml in a volumetric flask. Prepare a
Calculate the alumina content, w(Al,O,), expressed
fresh solution daily if required.
as a percentage by mass, using the calibration
graph, as follows:
3.3 Procedure
rnlV
w(Al,O,) = m x 100
Pipette 20 ml of stock solution A, prepared as in
21
2.4, into a 250 ml volumetric flask and dilute to vol-
ume with water. Pipette an aliquot, the amount of
where
which depends on the alumina content of the diluted
is the amount of alumina in the sample
stock solution, into a separating funnel of volume
ml
solution, in milligrams, corrected for the
100 ml.
blank value taken from the calibration
For an alumina content up to and including
graph;

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SIST EN ISO 10058:1998
IS0 10058:1992(E)
V is the volume, in millilitres, of diluted
4.3 Procedure
stock solution (see 3.3);
Dilute 50 ml of stock solution A, prepared as in 2.4,
is the mass, in milligrams, of sample
in2
to 250 ml with water in a one-mark volumetric flask.
contained in the aliquot of stock solution
Transfer 5 ml of this diluted stock solution (B) into a
A, as used for preparation of the diluted
100 ml one-mark volumetric flask. Then add in the
stock solution;
following order: 10 ml of the hydroxylammonium
chloride solution (4.2.2), 5 ml of phenanthroline
V is the aliquot, in millilitres, taken from the
1
(4.2.3) and 10 ml of ammonium acetate solution
diluted stock solution.
(4.2.1). Allow to stand for 15 min, make up to the
mark with water and mix by shaking. Measure the
4 Determination of total iron calculated as
absorbance of the solution at 20 “C + 2 OC, at a
-
iron(lll) oxide wavelength of 510 nm, using water as a reference
solution.
4.1 Principle
Make a blank measurement using the reagents
without the stock solution, and subtract this
Prepare a second diluted stock solution (B) from the
measurement from the result.
stock solution A prepared as in 2.4. This also serves
for the determination of calcium and magnesium.
By adding hydroxylammonium chloride to an aliquot
of this diluted stock solution, reduce the iron to its
divalent form. On adding l,lO-phenanthroline and
4.4 Plotting the calibration graph
buffering with ammonium acetate, an orange-
coloured ferrous phenanthroline complex will form,
Pipette 0 ml, 1 ml, 2 ml, 4 ml, 5 ml and 10 ml vol-
the intensity of which is determined photometrically.
umes of iron(lll) oxide standard solution (4.2.5) into
The absorbance maximum of this complex lies at a
six 100 ml volumetric flasks and proceed as in 4.3.
wavelength of 510 nm. By an appropriate dilution of
Use these results to plot a calibration graph, making
the measuring solution iron(lll) contents up to about
the necessary corrections for blank solutions (see
15 % may be determined.
. .
4 3)
4.2 Reagents
4.2.1 Ammonium acetate solution.
4.5 Calculation
See 3.2.4.
Calculate the iron(lll) oxide content, w(Fe,O,), ex-
4.2.2 Hydroxylammonium chloride solution.
pressed as a percentage by mass, using the cali-
bration graph, as follows:
Dissolve 5 g of hydroxylammonium chloride in
250 ml of water.
w(Fe,Q,) = m x 100
2 1
4.2.3 1 ,lO-phenanthroline solution.
See 3.2.3.
is the mass of iron(lll) oxide in the sam-
n21
4.2.4 Iron(W) oxide stock solution
ple solution, in milligrams, corrected for
(I,2 mg Fe,O,/ml).
the blank value taken from the calibration
graph;
Weigh into a beaker I,2 g + 0,001 g of iron(lll) oxide,
which has been dried at 110 “C + 2 “C to constant
V is the volume, in millilitres, of diluted
mass, and dissolve, while heating gently with 25 ml
stock solution (see 4.3);
of hydrochloric acid (2.2.5). Cool to 20 “C and dilute
to 1 000 ml with water in a volumetric flask.
is the mass, in milligrams, of sample
m2
contained in the aliquot of stock solution
4.2.5 Iron( I II) oxide standard solution A, as used for preparation of the diluted
(0,06 mg Fe,O,/ml). stock solution:
Dilute 25 ml of the stock solution (4.24) to 500 ml V is the aliquot, in millilitres, taken from the
1
with water in a volumetric flask. diluted stock solution.

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SIST EN ISO 10058:1998
IS0 10058:1992(E)
peroxide solution to one of the flasks and allow to
5 Determination of titanium(W) oxide
stand for 10 min, then fill up both flasks to 100 ml
with water and stir vigorously.
5.1 By formation of a complex with hydrogen
peroxide
Measure the absorbance of the solution at
20 “C + 2 “C against the solution without the ad-
5.1 .I Principle dition of hydrogen peroxide using a wavelength of
400 nm.
Mix an aliquot of stock solution A, prepared as in
NOTE 4 The solution should be fil tered or centrifuged
2.4, with sulfuric acid and hydrogen peroxide sol-
to remove zirconium phosphate.
ution, and measure the yellow colour photo-
metrically.
51.4 Plotting the calibration graph
Titanium(lV) oxide contents of up to 0,5 % can be
measured. However, vanadium interferes because
Pipette 0 ml, 10 ml, 20 ml, 40 ml and 50 ml volumes
of the formation of a similar yellow coloured com-
of titanium(lV) oxide standard solution (5.1.2.5) into
plex, and if more than 0,l % vanadium pentoxide is
two series of five 100 ml volumetric flasks.
present, the method given in 5.2 is used.
Add 5 ml of sulfuric acid (5.1.2.3) and 10 ml of
Interference may also be caused by deposits of
phosphoric acid (5.1.2.2) to all the flasks. Then add
zirconium phosphate, which should be removed by
to one of each pair of volumetric flasks, 10 ml of hy-
filtering or centrifuge.
drogen peroxide solution (5.1.2.1) and allow to stand
for 10 min, then fill up both flasks to 100 ml with
5.1.2 Reagents water and stir vigorously. Measure the absorbance
of the solution at 20 “C + 2 “C, against the solution
without the addition of hydrogen peroxide, using a
51.2.1 Hydrogen peroxide solution, 6 % (20 vol-
wavelength of 400 nm (see also 5.1.3).
umes).
5.1.2.2 Phosphoric acid solution, diluted 2 + 3. 51.5 Calculation
Add 400 ml of phosphoric acid (I,7 g/ml) to 600 ml
Calculate the titanium(lV) oxide content, w(TiO,),
of water, then mix and allow to cool.
expressed as a percentage by mass, using the ca
...