Nickel alloys -- Determination of lead -- Electrothermal atomic absorption spectrometric method

ISO 11437:2018 specifies an electrothermal atomic absorption spectrometric method for the determination of lead in the range of 1 µg/g to 10 µg/g in nickel alloys.

Alliages de nickel -- Détermination du plomb -- Méthode par spectrométrie d'absorption atomique électrothermique

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Status
Published
Publication Date
02-Jan-2018
Current Stage
6060 - International Standard published
Start Date
02-Dec-2017
Completion Date
03-Jan-2018
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INTERNATIONAL ISO
STANDARD 11437
First edition
2018-01
Nickel alloys — Determination of lead
— Electrothermal atomic absorption
spectrometric method
Alliages de nickel — Détermination du plomb — Méthode par
spectrométrie d'absorption atomique électrothermique
Reference number
ISO 11437:2018(E)
ISO 2018
---------------------- Page: 1 ----------------------
ISO 11437:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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Published in Switzerland
ii © ISO 2018 – All rights reserved
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ISO 11437:2018(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 1

5 Reagents ........................................................................................................................................................................................................................ 1

6 Apparatus ..................................................................................................................................................................................................................... 2

7 Instrument criteria ............................................................................................................................................................................................ 3

7.1 Preparation of solutions required for testing criteria ........................................................................................... 3

7.2 Characteristic mass ............................................................................................................................................................................. 3

7.3 Minimum precision ............................................................................................................................................................................. 3

7.4 Limit of detection .................................................................................................................................................................................. 3

7.5 Linearity ......... ............................................................................................................................................................................................... 4

8 Sampling and sample preparation .................................................................................................................................................... 4

9 Procedure..................................................................................................................................................................................................................... 4

9.1 Preparation of the test solution ................................................................................................................................................ 4

9.2 Blank test ..................................................................................................................................................................................................... 4

9.3 Preparation of the calibration solutions ........................................................................................................................... 4

9.4 Calibration and determination .................................................................................................................................................. 4

9.4.1 Adjustment of the atomic absorption spectrometer......................................................................... 4

9.4.2 Atomic absorption measurements ................................................................................................................... 5

9.5 Number of determinations ........................................................................................................................................................... 5

10 Expression of results ........................................................................................................................................................................................ 6

10.1 Calculation .................................................................................................................................................................................................. 6

10.2 Precision ....................................................................................................................................................................................................... 6

10.2.1 Interlaboratory tests .................................................................................................................................................... 6

10.2.2 Precision data ..................................................................................................................................................................... 6

11 Test report ................................................................................................................................................................................................................... 7

Annex A (normative) Optimization and checking of spectrometer performance criteria ...........................8

Bibliography .............................................................................................................................................................................................................................15

© ISO 2018 – All rights reserved iii
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ISO 11437:2018(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.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

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. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following

URL: www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 155, Nickel and nickel alloys.

This first edition cancels and replaces ISO 11437-1:1994 and ISO 11437-2:1994, which have been merged

and technically revised.
iv © ISO 2018 – All rights reserved
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INTERNATIONAL STANDARD ISO 11437:2018(E)
Nickel alloys — Determination of lead — Electrothermal
atomic absorption spectrometric method
1 Scope

This document specifies an electrothermal atomic absorption spectrometric method for the

determination of lead in the range of 1 µg/g to 10 µg/g in nickel alloys.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 648, Laboratory glassware — Single-volume pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
3 Terms and definitions
No terms and definitions are listed in this document.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
4 Principle

Dissolution of a test portion in a mixture of nitric acid and hydrofluoric acid, dilution of the test solution

to a known volume, and transfer of an aliquot to a plastic vial.

Addition of a modifier to the aliquot of the test solution, and injection of a small volume of this solution

into the electrothermal atomizer of an atomic absorption spectrometer.

Measurement of the atomic absorption of the 283,3 nm spectral line energy emitted by a lead hollow-

cathode lamp and comparison with those of the calibration solutions.
5 Reagents

During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only

distilled water or water of equivalent purity.
5.1 Pure nickel, containing less than 1 µg/g of lead.
5.2 Nickel, base-solution 50 g/l.

Weigh, to the nearest 0,1 g, 25,0 g of pure nickel (5.1). Transfer to a 600 ml tall-form beaker and add

100 ml of water. Cautiously add 100 ml of nitric acid (ρ = 1,41 g/ml) in small portions, in such a

manner that the dissolution remains under control. Cool the solution and transfer it to a 500 ml one-

mark volumetric flask. Make up to the mark with water and mix.
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ISO 11437:2018(E)

If large nickel turnings or chunks are used, gentle heating may be required to complete the dissolution.

When using carbonyl nickel powder, the solution should be filtered to remove undissolved carbon.

5.3 Nickel, base solution 5 g/l.

Transfer 10,0 ml of the nickel base solution (5.2) to a 100 ml one-mark volumetric flask. Make up to the

mark with water and mix.
5.4 Nitric acid, ρ = 1,41 g/ml, diluted 1 + 1.
5.5 Hydrofluoric acid, ρ = 1,13 g/ml.

WARNING — Hydrofluoric acid is extremely irritating and corrosive to skin and mucous

membranes producing severe skin burns which are slow to heal. In case of contact with skin,

wash well with water, apply a topical gel containing 2,5 % (mass fraction) calcium gluconate and

seek immediate medical treatment.
5.6 Nitric/hydrofluoric acids, mixture.

Carefully add 150 ml of nitric acid (ρ = 1,41 g/ml) and 150 ml of hydrofluoric acid (5.5) to 150 ml of

water. Mix and store in a plastic bottle.
5.7 Modifier, nickel nitrate-ammonium phosphate solution.

Weigh, to the nearest 0,1 g, 6,0 g of ammonium dihydrogen orthophosphate (NH H PO ) and dissolve it

4 2 4

in 50 ml of water. Transfer the solution to a 100 ml one-mark volumetric flask. Add 20,0 ml of the nickel

base solution (5.2), make up to the mark with water and mix.
This solution shall be freshly prepared.
5.8 Lead, standard solution, 100 mg/l.

Weigh, to the nearest 0,001 g, 0,100 g of lead of a mass fraction of 99,9 % minimum purity and transfer

to a 250 ml beaker. Add 40 ml of nitric acid (5.6) and heat to assist dissolution. Cool the solution and

transfer it to a 1 000 ml one-mark volumetric flask. Make up to the mark with water and mix.

Store in a polyethylene bottle.
1 ml of this solution contains 0,1 mg of lead.
5.9 Lead, standard solution, 1 mg/l.

Transfer 10,0 ml of the lead standard solution (5.8) into a 1 000 ml one-mark volumetric flask. Add

20 ml of nitric acid (ρ = 1,41 g/ml). Make up to the mark with water and mix.
1 ml of this solution contains 1 µg of lead.
This solution shall be freshly prepared.
6 Apparatus

All volumetric glassware shall be class A and calibrated, in accordance with ISO 648 or ISO 1042 as

appropriate.

Before use, all glassware shall be cleaned by boiling with hydrochloric acid to remove any chemical

contamination.
6.1 Polytetrafluoroethylene (PTFE) beakers, of capacity 100 ml.
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ISO 11437:2018(E)
6.2 Plastic vials, of capacity 5 ml.
6.3 Plastic volumetric flasks, of capacities 50 ml and 100 ml.
6.4 Micropipettes, of capacities from 2,0 µl to 100 µl.
6.5 Atomic absorption spectrometer.

The atomic absorption spectrometer to be used shall be fitted with an electrothermal atomizer and

shall meet the performance criteria given in Annex A.

The atomic absorption spectrometer and electrothermal atomiser are satisfactory if, after optimization

according to Annex A (A.3 to A.6), they meet the criteria specified in 7.1.

The spectrometer shall be equipped with a background corrector and a fast recording system capable

of measuring peak heights and peak areas. The electrothermal atomizer shall be fitted with a pyrolytic

graphite tube and L’vov platform, or a normal graphite tube.

The spectrometer should be capable of using single-element hollow cathode lamps or electrodeless

discharge lamps operated at currents recommended by the manufacturer.
7 Instrument criteria
7.1 Preparation of solutions required for testing criteria

Follow the instructions given for the preparation of lead calibration solutions in 9.3 and 9.4.2.3. The

composition of these calibration solutions is given in Table 1.
Table 1 — Lead concentration of calibration solutions
Lead concentration
Calibration
solution
µg/litre ng/ml µg/g
S1 0 0 0
S2 10 10 2
S3 20 20 4
S4 30 30 6
7.2 Characteristic mass

The characteristic mass determined as described in A.7.1, shall be within 20 % of that given in the

manufacturer’s instructions.
7.3 Minimum precision

The minimum precision of calibration solution S4 shall not exceed 10 % of the mean absorbance of the

same solution, and the minimum precision of calibration solution S2 shall not exceed 4 % of the mean

absorbance of solution S4 when determined as described in A.7.2.
7.4 Limit of detection

The limit of detection of lead, determined as described in A.7.3, shall be less than 20 pg (equivalent to

1,0 µg/l or 0,2 µg/g).
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ISO 11437:2018(E)
7.5 Linearity

The linearity of the calibration, determined as described in A.7.4, shall not be less than 0,7.

8 Sampling and sample preparation

Sampling and preparation of the laboratory sample shall be carried out by normal agreed procedures

or, in case of dispute, by appropriate national standards.

The laboratory sample normally is in the form of turnings, millings or drillings and no further

mechanical preparation of the sample is necessary.

If it is suspected that the laboratory sample is contaminated with oil or grease from the milling or

drilling process, it shall be cleaned with high purity acetone and then dried in air.

If the laboratory sample contains particles or pieces of widely varying sizes, the test sample should be

obtained by riffling.
9 Procedure
9.1 Preparation of the test solution

Weigh, to the nearest 0,001 g, 0,500 g of the sample and transfer into a 100 ml PTFE beaker (6.1).

Add 20 ml of the acid mixture (5.6). Apply sufficient heat to initiate and maintain the reaction until

dissolution is complete.

Cool the solution and then transfer it into a 100 ml one-mark volumetric flask. Dilute to the mark with

water and mix.

Dissolving certain alloys in the nitric acid-hydrofluoric acid mixture is sometimes difficult. In such

cases, the proportions of the dissolving mixture should be adjusted, but a corresponding blank test is

necessary.
9.2 Blank test

In parallel with the determination and following the same procedure, carry out a blank test using the

same quantities of all reagents as used for the determination.
9.3 Preparation of the calibration solutions

Transfer 10,0 ml of the nickel base solution (5.2) into each of a series of 100 ml one-mark volumetric

flasks. Add 0 ml; 0,5 ml;1,0 ml; 2,0 ml; 3,0 ml; 4,0 ml; 5,0 ml and 6,0 ml of the lead standard solution

(5.9). Make up to the mark with water and mix.

These calibration solutions contain 0 µg; 5,0 µg; 10,0 µg; 20,0 µg; 30,0 µg; 40,0 µg; 50 µg and 60,0 µg of

lead per litre.
9.4 Calibration and determination
9.4.1 Adjustment of the atomic absorption spectrometer

Equip the atomic absorption spectrometer with a pyrolytic graphite tube fitted with a L’vov platform.

Condition new graphite tubes as instructed by the manufacturer.
Set up the instrument conditions for
— measuring peak area integration absorbance at a wavelength of 283,3 nm, and
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ISO 11437:2018(E)
— using an injection volume of 20 µl.

NOTE The volume injected into the furnace may be different, depending on the sensitivity of the instrument.

Establish the optimum furnace temperature programme in accordance with the instructions given in

Annex A.
9.4.2 Atomic absorption measurements
9.4.2.1 General

The procedures described in this subclause shall be carried out immediately prior to the measurement.

9.4.2.2 Lead contents of up to 5,0 µg/g

With a micropipette (6.4) transfer 1,0 ml of each test solution containing up to 25 µg/l of lead and of each

calibration solution containing up to 30 µg/l of lead into 5 ml plastic vials (6.2). With a micropipette

(6.4), add 100 µl of the modifier solution (5.4) and mix.
9.4.2.3 Lead contents between 5,0 µg/g to 10,0 µg/g

With a micropipette (6.4) transfer 0,50 ml of each test solution containing between 25 µg and 50 µg of

lead per litre, and of the calibration solutions containing 0 µg; 20,0 µg; 40,0 µg; 50 µg and 60,0 µg of lead

per litre, into 5 ml plastic vials (6.2). With micropipettes (6.4), add 0,50 ml of the nickel base solution

(5.3) and 100 µl of the modifier solution (5.4) and mix.

NOTE 1 If the electrothermal atomizer is fitted with an autosampler, the addition of modifier, dilution and

mixing can be done in the autosampler cups.

NOTE 2 Mixing can be carried out by repeated charging and discharging of the contents of the plastics vial

using the largest micropipette.
9.4.2.4 Preparation of the calibration curves

Atomize the preselected volume of each calibration solution and record three absorbance measurements

for each of them.
Subtract the mean absorbance value obtained for the 0 µg/l calibration solution
...

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