SIST EN ISO 11215:1999

SLOVENSKI STANDARD
01-maj-1999
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Modified starch - Determination of adipic acid content of acetylated di-starch adipates -
Gas-chromatographic method (IS0 11215:1998)
Modifizierte Stärke - Bestimmung des Gehalts an Adipinsäure in acetylierten Di-Stärke-
Adipaten - Gaschromatographisches Verfahren (ISO 11215:1998)
Amidons et fécules modifiés - Détermination de la teneur en acide adipique dans les
adipates de diamidon acétylés - Méthode par chromatographie en phase gazeuse (ISO
11215:1998)
Ta slovenski standard je istoveten z: EN ISO 11215:1998
ICS:
67.180.20 Škrob in izdelki iz njega Starch and derived products
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 11215
First edition
1998-05-15
Modified starch — Determination of adipic
acid content of acetylated di-starch
adipates — Gas chromatographic method
Amidons et fécules modifiés — Détermination de la teneur en acide
adipique dans les adipates de diamidon acétylés — Méthode par
chromatographie en phase gazeuse
A
Reference number
ISO 11215:1998(E)
ISO 11215:1998(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.
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 11215 was prepared by Technical Committee
ISO/TC 93, Starch (including derivatives and by-products).
Annexes A to C of this International Standard are for information only.
©  ISO 1998
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
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ii
©
INTERNATIONAL STANDARD  ISO ISO 11215:1998(E)
Modified starch — Determination of adipic acid content of
acetylated di-starch adipates — Gas chromatographic method
1  Scope
This International Standard specifies a method for the gas chromatographic determination of total adipic content
and free adipic acid content of acetylated di-starch adipates.
2  Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of the publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on the International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain
registers of currently valid International Standards.
ISO 1666:1996, Starch — Determination of moisture content — Oven-drying method
ISO 3696:1987, Water for analytical laboratory use — Specification and test methods
3  Principle
The test portion is dispersed in moderately concentrated sodium hydroxide solution, to hydrolyse fully the adipate
from the starch. After acidification, the free adipic acid is extracted with ethyl acetate. The ethyl acetate is removed,
and the dry residue is silylated. An aliquot portion of this solution is injected into a gas chromatograph equipped with
a capillary column. Pimelic acid is used as internal standard.
Free adipic acid is extracted by washing out the starch with water, acidifying the extract, and extracting the free acid
with ethyl acetate.
The determination is performed by silylation and gas chromatography as described above.
4  Reagents and materials
Use only reagents of recognized analytical grade.
4.1 Water, complying with at least grade 3 in accordance with ISO 3696.
4.2 Waxy maize starch, commercial grade.
NOTE  Waxy maize starch is chosen as the base material, as it represents the bulk of starch adipate on the market. This may
be substituted with another native starch, if appropriate.
©
ISO
ISO 11215:1998(E)
4.3 Adipic acid solution, r(C H O ) = 50,0 mg/l.
6 10 4
4.4 Pimelic acid solution, r(C H O ) = 50,0 mg/l.
7 12 4
4.5 Sodium hydroxide solution, c(NaOH) = 4 mol/l.
4.6 Hydrochloric acid, concentrated, c(HCl) = 12 mol/l.
4.7 (C H O ).
Ethyl acetate
4 8 2
4.8 Nitrogen gas, purity 99 %.
4.9 Acetonitrile
4.10 Silylation reagent: bis(trimethylsilyl)trifluoroacetamide (BSTFA) which includes 1 % trimethylchlorosilane
(TMCS).
4.11 Helium gas, purity 99,9999 % (e.g. grade N60).
4.12 Hydrogen gas, purity 99,99 % (e.g. grade N400 or better).
4.13 Air, purity 99,999 % (e.g. grade S).
5  Apparatus
Usual laboratory apparatus and, in particular, the following.
5.1 Glass reaction tubes, 100 mm x 16 mm, with screw caps fitted with polytetrafluoroethylene (PTFE) covered
rubber seals resistant to concentrated hydrochloric acid (4.6).
5.2 Pipettes, adjustable, of 1,00 ml and 5,00 ml capacity, accurate to 0,01 ml.
NOTE  The pipettes should be tested to see if they comply to manufacturer's tolerance. Calibration may be required.
5.3 Rotary shaker.
5.4 Pasteur pipettes.
5.5 Heating device, capable of being maintained at (30 ± 2) °C.
1)
5.6 Evaporation device, based on solvent removal with a stream of nitrogen (e.g. Pierce Reacti-Vap III) .
5.7 Ultrasonic bath, power 120 W.
5.8 Gas chromatograph, accommodating capillary columns, fitted with a flame ionization detector, on-column
injector, and a computer integrator. See annex A for typical conditions for chromatography.
5.9 Sieve, 800 μm.
5.10 Blade mill.
5.11 Laboratory centrifuge, capable of operating at a radial acceleration of 1 100 g .
n
___________
1)
Pierce Reacti-Vap III is an example of suitable apparatus available commercially. This information is given for the
convenience of users of this International Standard and does not constitute an endorsement by ISO of this apparatus.
©
ISO
ISO 11215:1998(E)
6  Sampling
It is important that the laboratory receive a sample which is truly representative and has not been damaged or
changed during transport or storage.
Sampling is not part of the method specified in this International Standard.
7  Preparation of test sample
Sieve the laboratory sample through the 800 μm sieve (5.9). If the material does not pass through the sieve, then
grind the sample with a blade mill (5.10) until it passes completely through the 800 μm sieve. Homogenize the
sample.
8  Procedure
8.1  Calibration for total adipic acid content
8.1.1 Weigh, to the nearest 0,1 mg, approximately 50 mg of waxy maize starch (4.2) into each of four glass
reaction tubes (5.1).
8.1.2 Into one tube, pipette (5.2) 1,00 ml of adipic acid solution (4.3) and into the others 0,75 ml, 0,50 ml and
0,25 ml, respectively, of adipic acid solution (4.3).
8.1.3 Adjust the volume in each tube to 1,5 ml with water (4.1) and add 1,00 ml of pimelic acid solution (4.4) to
each tube. Each tube then contains 50 μg of pimelic acid, and 50,0 μg, 37,5 μg, 25,0 μg and 12,5 μg respectively of
adipic acid.
NOTE  It is possible that pimelic acid contains some adipic acid. If this is proven, a fifth tube should be prepared in a similar
fashion but without addition of adipic acid solution (4.3).
8.1.4 Agitate the tubes manually to disperse the starch fully. Add 2,5 ml of sodium hydroxide solution (4.5).
8.1.5 Seal the tubes well and place on the rotary shaker (5.3) for 5 min.
8.1.6 Remove the tubes and, with cooling, add 1,0 ml of hydrochloric acid (4.6). Mix well.
8.1.7 Add 5 ml of ethyl acetate (4.7). Seal the tubes tightly and shake vigorously for 1 min.
8.1.8 Let the tubes stand until good phase separation is achieved. With a Pasteur pipette (5.4), transfer the
supernatant layer (ethyl acetate) to a clean screw-top tube.
Make sure that none of the aqueous layer is carried over with the organic layer.
8.1.9 Place the tubes in the heating device (5.5) set at 30 °C, and evaporate the ethyl acetate completely under a
stream of nitrogen (4.8) with the evaporation device (5.6).
8.1.10 Repeat steps 8.1.7 to 8.1.9 three times more, accumulating the dried residue in the same tube.
8.1.11 Dissolve the total residue in 0,6 ml of acetonitrile (4.9) and place the closed tubes in the ultrasonic bath
(5.7) for 2 min.
8.1.12 Add 0,3 ml of the silylation reagent (4.10). Close the tubes and homogenize in the ultrasonic bath for 2 min.
8.1.13 Place the tubes in the heating device (5.5) set at 30 °C, for 30 min to complete derivatization.
©
ISO
ISO 11215:1998(E)
8.1.14 Inject 0,5 μl of the solution into the gas chromatograph. See annex A for typical conditions for
chromatography.
8.2  Total adipic acid content
8.2.1 Weigh, to the nearest 0,1 mg, approximately 50 mg of the prepared test sample into a glass reaction tube
(5.1).
8.2.2 Add 1,5 ml of water (4.1) a
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