EN ISO 11212-2:1997

SLOVENSKI STANDARD
01-november-1998
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Starch and derived products - Heavy metals content - Part 2: Determination of mercury
content by atomic absorption spectrometry (ISO 11212-2:1997)
Stärke und Stärkederivate - Schwermetallgehalt - Teil 2: Bestimmung des
Quecksilbergehaltes durch Atomabsorptionsspektrometrie (ISO 11212-2:1997)
Amidons, fécules et produits dérivés - Teneur en métaux lourds - Partie 2: Détermination
de la teneur en mercure par spectrométrie d'absorption atomique (ISO 11212-2:1997)
Ta slovenski standard je istoveten z: EN ISO 11212-2:1997
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 Is0
11212-2
STANDARD
First edition
1997003- 15
Starch and derived products - Heavy
metals content -
Part 2:
Determination of mercury content by atomic
absorption spectrometry
Amidons, f&u/es et produits d&iv& - Teneur en mbtaux lourds -
Parfie 2: Dbtermination de la teneur en mercure par spectrom&rie
d ’absorption atomique
Reference number
IS0 11212-2:1997(E)
IS0 11212-2: 1997(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, governmental 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 International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 11212-2 was prepared by Technical Committee
ISOKC 93, Starch (including derivatives and by-products).
IS0 11212 consists of the following parts, under the general title Starch
and derived products - Heavy metals content.
- Part 1: Determination of arsenic content by atomic absorption
spectrometry
- Part 2: Determination of mercury content by atomic absorption
spectrometry
- Part 3: Determination of lead content by atomic absorption
spectrometry with electrothermal atomization
- Part 4: Determination of cadmium content by atomic absorption
spectrometry with electrothermal atomization
Annex A of this part of IS0 11212 is for information only.
0 IS0 1997
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.
International Organization for Standardization
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Internet
central @ iso.ch
x.400 c=ch; a=400net; p=iso; o=isocs; s=central
Printed in Switzerland
ii
INTERNATIONAL STANDARD o 1s0 IS0 11212=2:1997(E)
Starch and derived products - Heavy metals content -
Part 2:
Determination of mercury content by atomic absorption spectrometry
1 Scope
This part of IS0 11212 specifies a method for the determination of the mercury content of starch, including
derivatives and by-products, by atomic absorption spectrometry with cold-vapour generation.
The cold-vapour generators currently available use very different techniques; it is thus impossible to propose a
comprehensive method likely to ensure the attainment of satisfactory results on all types of apparatus. Each analyst
should therefore optimize the conditions of use of his/her own apparatus on the basis of general or particular
instructions.
2 Definition
For the purposes of this part of IS0 11212, the following definition applies.
2.1 mercury content: Quantity of mercury determined in accordance with the conditions specified in this method
and expressed as mercury (Hg), in micrograms per kilogram of the product as received.
3 Principle
Wet digestion of the organic matrix. Reduction of mercury (Hg2+) to metallic mercury by hydrogen resulting from the
action of sodium borohydride (or tin(ll) chloride) on hydrochloric acid. Entrainment of the mercury vapour by a flow
of gas and determination of monoatomic mercury vapour by atomic absorption spectrometry in a quartz cell.
Measurement of the absorbance at a wavelength of 253,7 nm.
Determination of the concentration of mercury in the sample by means of a calibration curve.
4 Reagents
Use only reagents of recognized analytical grade and distilled water or water of equivalent purity.
4.1 Nitric acid (p20 = I,38 g/ml).
4.2 Hydrogen peroxide, 30 % (WV) solution.

0 IS0
IS0 11212=2:1997(E)
4.3 Sodium borohydride solution
Prepare a solution at the concentration recommended in the instructions for use of the cold-vapour generator (5.3).
4.4 Tin(N) chloride solution
Prepare a solution at the concentration recommended in the instructions for use of the cold-vapour generator (5.3).
4.5 Hydrochloric acid solution
Prepare a solution at the concentration recommended in the instructions for use of the cold-vapour generator (5.3).
4.6 Mercury standard solution, 1 g/l.
Standard solutions are commercially available at this concentration. These solutions may be prepared by weighing
and dissolving the salt or metal of known purity.
4.7 Calibration solutions
Before each series of measurements, prepare from the standard mercury solution (4.6) at least five calibration
solutions covering the range of concentrations to be determined. 100 ml of each calibration solution shall contain
7,5 ml of nitric acid (4.1).
5 Apparatus
All the glassware used shall be previously washed by means of suitable products (such as nitric acid) and rinsed
with distilled water to eliminate any trace of mercury.
Use ordinary laboratory apparatus and, in particular, the following.
5.1 Digestion apparatus (see figure l), made of borosilicate glass and consisting of three elements terminating
with conical ground joints (5.1 .l to 5.1.3).
5.1.1 Soxhlet extraction tube, of capacity 200 ml, equipped with a stopcock and a lateral tube connected directly
to the flask (5.1.3).
5.1.2 Cooling apparatus, 35 cm long, connected to the top of the Soxhlet extraction tube (5.1 .I).
5.1.3 Round-bot
...