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APMP.QM-S5

Essential and Toxic Elements in Seafood

Final Report

Authors:

Liliana Valiente (INTI)1, John W. Bennett (ANSTO)

2, Rodrigo Caciano de Sena

(INMETRO)3, Boriana Kotzeva (BIM)

4, Gabriela Massiff (CMQ)

5, Jingbo Chao and Jun

Wang (NIM)6, Randa Nasr (NIS)

7, Guillaume Labarraque (LNE)

8, Elias Kakoulidis Eugenia

Lampi (EIM)9, Della Wai-mei Sin, Chuen-shing Mok, Siu-kay Wong and Yiu-chung Yip

(GLHK)10

, Shankar Gopala Aggarwal Prabhat K. Gupta (NPLI)11

, Yanbei Zhu and Shin-ichi Miyashita (NMIJ)

12, Yong-Hyeon Yim (KRISS)

13, Osman Zakaria (SIRIM)

14, Judith Velina

Lara Manzano (CENAM)15

, Richard Shin (HSA)16

, Milena Horvat (JSI)17

, Charun Yafa (NIMT)

18

1 Instituto Nacional de technologia Industrial/Quimica, Argentina

2 Australian Nuclear Science and Technology Organisation, Australia

3 Instituto Nacional de Metrologia, Normalizacaoe Qualidade Industrial, Brazil

4 Bulgarian Institute of Metrology, National Centre of Metrology, Bulgaria

5 Chemical Metrology Center, Fundacion Chile

6 National Institute of Metrology, China

7 National Institute for Standards, Egypt

8 Laboratorie national de metrologie et d’essais, France

9 Hellenic Metrology Institute, EXHM, Greece

10 Government Laboratory, Hong Kong, China

11 CSIR-National Physical Laboratory, India

12 National Metrology Institute of Japan, Japan

13 Korean Research Institute of Standards & Science, Korea

14 National Metrology Laboratory, SIRIM BERHAD, Malaysia

15 Centro Nacional de Metrologia, Mexico

16 Health Sciences Authority, Singapore

17 Jozef Stefan Institute, Department of Environmental Sciences, Slovenia

18 National Institute of Metrology, Thailand

Abstract

The Supplementary Comparison APMP.QM-S5 was undertaken to demonstrate the

capability of participating national metrology institutes (NMIs) and designated institutes

(DIs) in measuring the contents of the incurred essential elements (iron and zinc) and toxic

elements (total arsenic and cadmium) at g/g levels in a test sample of dried shrimp by

various analytical techniques.

At the APMP TCQM Meeting held in Pattaya, Thailand in November 2010, Government

Laboratory of the Government of the Hong Kong Special Administrative Region (GLHK)

proposed this APMP supplementary comparison. The proposal was further discussed and

agreed upon at the CCQM Inorganic Analysis Working Group Meeting held in Paris in April

2011. GLHK was the coordinating laboratory for the supplementary comparison. For

enhancing the collaboration amongst specialized regional bodies in Asia-Pacific and to help

build the laboratory capacity of NMIs/DIs from developing economies, the reference values

of the supplementary comparison are used for evaluation of performance of participants of

an APMP proficiency testing programme (APMP PT 11-01), an Asia-Pacific Laboratory

Accreditation Cooperation proficiency testing programme (APLAC T082) and an

Asia-Pacific Economic Co-operation proficiency testing programme (APEC PT), which

were concurrently run using the same testing material as in APMP.QM-S5.

The supplementary comparison serves to facilitate claims by participants on the Calibration

and Measurement Capabilities (CMCs) as listed in Appendix C of the Key Comparison

Database (KCDB) under the Mutual Recognition Arrangement of the International

Committee for Weights and Measures (CIPM MRA).

Totally 18 institutes registered for the supplementary comparison and all of them submitted

their results. Most of the participants used microwave acid digestion methods for sample

dissolution. For the instrumental determination, a variety of techniques like ICP-MS,

ICP-OES, INAA and AAS were employed by the participants. For this supplementary

comparison, inorganic core capabilities have been demonstrated by concerned participants

with respect to methods including ICP-MS (without isotope dilution), ID-ICP-MS, ICP-OES,

INAA and AAS on the determination of total arsenic, cadmium, iron and zinc in a matrix of

seafood.

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Table of Content

Page

1 Introduction 2

2 Participating Institutes 3

3 Samples and Instructions to Participants 4

3.1 Materials 4

3.2 Homogeneity and Stability Study 4

3.3 Instructions to Participants 6

4 Methods of Measurement 7

5 Results and Discussion 11

5.1 General 11

5.2 Calculation of reference mass fraction values and associated

uncertainties

16

5.3 Equivalence statements 23

6 Demonstration of Core Capabilities 32

7 Conclusion 32

Acknowledgement 33

References 33

Appendix 34

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1. Introduction

Food contamination with toxic elements is one of the major food safety issues in the

Asia-Pacific region. Most economies have laboratories that carry out routine analyses of

toxic elements in seafood for regulatory compliance and surveillance purposes.

Examinations of essential elements are performed for nutritional studies and quality

assurance.

The Asia-Pacific Metrology Programme (APMP) has been organizing inter-comparisons for

the purpose of establishing the technical basis for mutual recognition of measurement

capabilities among national metrology institutes (NMIs)/designated institutes (DIs) in the

Asia-Pacific region and worldwide. At the APMP TCQM Meeting held in Pattaya,

Thailand in November 2010, Government Laboratory of the Government of the Hong Kong

Special Administrative Region (GLHK) proposed an APMP supplementary comparison

(APMP.QM-S5) on the determination of essential elements (iron and zinc) and toxic

elements (total arsenic and cadmium) in a dried shrimp material. The proposal was further

discussed and agreed upon at the CCQM Inorganic Analysis Working Group Meeting held in

Paris in April 2011. For enhancing the collaboration amongst specialized regional bodies in

Asia-Pacific and to help build the laboratory capacity of NMIs/DIs from developing

economies, the reference values of the supplementary comparison would be used for

evaluation of performance of participants of an APMP proficiency testing programme

(APMP PT 11-01), an Asia-Pacific Laboratory Accreditation Cooperation proficiency testing

programme (APLAC T082) and an Asia-Pacific Economic Co-operation proficiency testing

programme (APEC PT), which are concurrently run using the same testing material as in

APMP.QM-S5. Dried shrimps are prepared by drying of seawater shrimps under the sun and

are commonly consumed to impart a characteristic flavour to many Asian cuisines. The

study is based on the analysis of naturally incurred materials. Its aim is to demonstrate the

capability of participating NMIs and DIs in measuring the contents of the incurred analytes

(iron, zinc, total arsenic and cadmium) at g/g levels in a test sample of dried shrimp by

various analytical techniques.

The supplementary comparison serves to facilitate claims by participants on the Calibration

and Measurement Capabilities (CMCs) as listed in Appendix C of the Key Comparison

Database (KCDB) under the Mutual Recognition Arrangement of the International

Committee for Weights and Measures (CIPM MRA). Participants are requested to complete

the Inorganic Core Capabilities Tables as a means of providing evidence for their CMC

claims.

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2. Participating Institutes

Totally 18 institutes registered for the Supplementary Comparison APMP.QM-S5. The list

showing the countries’ names of the participating NMIs/DIs in alphabetical order is given in

Table 1.

Table 1. List of participating NMIs/DIs for APMP.QM-S5

No. Institute Country Contact person

Results

submitted for

measurand

1

INTI

Instituto Nacional de technologia

Industrial/Quimica

Argentina Liliana Valiente As, Cd, Fe, Zn

2

ANSTO

Australian Nuclear Science and Technology

Organisation

Australia John W. Bennett As, Fe, Zn

3

INMETRO

Instituto Nacional de Metrologia,

Normalizacaoe Qualidade Industrial

Brazil Rodrigo Caciano

de Sena As, Cd, Fe, Zn

4

BIM

Bulgarian Institute of Metrology, National

Centre of Metrology

Bulgaria Boriana Kotzeva Zn

5 CMQ

Chemical Metrology Center, Fundacion Chile Chile Gabriela Massiff As, Cd, Fe, Zn

6 NIM

National Institute of Metrology, P.R. China China

Jingbo Chao

Jun Wang As, Cd, Fe, Zn

7 NIS

National Institute for Standards Egypt Randa Nasr As, Cd, Fe, Zn

8 LNE

Laboratorie national de metrologie et d’essais France

Guillaume

Labarraque As, Cd, Fe

9 EIM

Hellenic Metrology Institute, EXHM Greece

Elias Kakoulidis

Eugenia Lampi As, Cd, Fe, Zn

10 GLHK

Government Laboratory, Hong Kong, China

Hong Kong,

China Yiu-chung Yip As, Cd, Fe, Zn

11 NPLI

CSIR-National Physical Laboratory India

Shankar Gopala

Aggarwal

Prabhat K. Gupta

As, Cd, Fe, Zn

12 NMIJ

National Metrology Institute of Japan Japan

Yanbei Zhu,

Shin-ichi Miyashita As, Cd, Fe, Zn

13

KRISS

Korean Research Institute of Standards &

Science

Korea,

Republic of Yong-Hyeon Yim As, Cd, Fe, Zn

14

SIRIM

National Metrology Laboratory, SIRIM

BERHAD

Malaysia Osman Zakaria As, Cd, Fe, Zn

15 CENAM

Centro Nacional de Metrologia Mexico

Judith Velina Lara

Manzano As, Cd, Fe, Zn

16 HSA

Health Sciences Authority Singapore Richard Shin Fe

17

JSI

Jozef Stefan Institute, Department of

Environmental Sciences

Slovenia Milena Horvat As, Cd, Fe, Zn

18 NIMT Thailand Charun Yafa As, Cd, Fe, Zn

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No. Institute Country Contact person

Results

submitted for

measurand

National Institute of Metrology (Thailand)

Remarks: (i) KRISS did not submit results for Fe due to contamination problems found by the institute.

(ii) Both NMIJ and JSI submitted two sets of results using different determination techniques.

3. Samples and Instructions to Participants

3.1. Materials

About 13 kg of dried shrimps was purchased from the local market in Hong Kong. The dried

shrimps were confirmed to contain quantities of incurred iron, zinc, arsenic and cadmium.

The dried shrimps were rinsed with anhydrous methanol to remove dirt and foreign matter

and air-dried in a Class 1000 cleanroom. The air-dried shrimps were blended in a high-speed

blender (25000 revolutions per minute), then de-fatted with n-hexane and air-dried in the

cleanroom. The air-dried sample was further blended and ground to powder using a

high-speed blender (25000 revolutions per minute). The powder was subject to a sieving

process through 200 m calibrated sieves. The sieved powder was thoroughly homogenized

in a 3-dimensional mixer for 5 days. The powdered material was irradiated using a 137

Cs

gamma source at a dose of about 10 kGy for disinfection. The irradiated material was

packed into pre-cleaned and nitrogen-flushed amber glass bottles. About 300 bottles, each

containing about 25 g of powered sample, were prepared. Finally, each bottled sample was

vacuum-sealed in a polypropylene bag and stored at room temperature (20 ± 5 C) prior to

distribution or use.

3.2. Homogeneity and Stability Study

The homogeneity study was conducted after the testing material was bottled and irradiated.

10 bottles of the test material (conditioned at 20 ± 5 C) were randomly selected from the

whole lot of bottles prepared. Two test portions of 0.5 g were taken from each bottle for

analysis.

The test portions were digested using microwave-assisted digestion. Following validated

procedures, the digested samples and method blanks were analysed using standard additions

with high resolution ICP-MS for the analysis of As, Cd and Zn, and using standard additions

with ICP-AES for the analysis of Fe.

ANOVA technique was applied to assess the between-bottle heterogeneity and the standard

uncertainty originated from the between-bottle heterogeneity was calculated using the

equation (1) given below in accordance with ISO Guide 35:2006 [1]. The results are

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summarized in Table 2.

within

withinbb

2

MSνn

MSu (1)

where

ubb is the standard uncertainty due to between bottles heterogeneity;

MSwithin is the mean square of within bottles variance;

MSwithin is the degree of freedom of MSwithin;

n is the number of replicates.

Table 2. Summary of homogeneity study results

Measurand ANOVA test on heterogeneity Relative standard uncertainty due to

between-bottle heterogeneity, ubb (%) F-statistics Critical value

As 1.22 3.02 0.95

Cd 2.08 3.02 1.21

Fe 1.25 3.02 1.05

Zn 1.40 3.02 1.26

The homogeneity study results indicated that no significant heterogeneity was observed in

the test material. The test material was considered fit for the purpose of the supplementary

comparison.

Long-term and short-term stability studies were conducted for the test material using the

same analytical procedures as for the homogeneity study. The long-term stability is

associated with the behavior of the test material under storage in participating laboratories

while the short-term stability studies aimed to show the stability of the material during its

transport. The long-term stability was conducted at 20 ºC covering the period from the

distribution of test material to the deadline for submission of results. The short-term stability

was conducted at 40 ºC and 50 ºC over a 4-week period (sampling points: 1 week, 2 weeks

and 4 weeks).

The trend-analysis technique proposed by ISO Guide 35:2006 [1] was applied to assess the

stability of the test material at 20 ºC, 40 ºC and 50 ºC. The basic model for the stability study

is expressed as the equation (2).

Y = 0 + 1X + (2)

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where 0 and 1 are the regression coefficients; and denotes the random error component.

With appropriate t-factors, 1 can be tested for significance of deviation from zero. Table 3

summarizes the results of the stability tests at 20 ºC, 40 ºC and 50 ºC respectively.

Table 3. Summary of stability study results

Measurand p-value for significance test for 1

20 ºC 40 ºC 50 ºC

As 0.267 0.583 0.931

Cd 0.173 0.649 0.640

Fe 0.142 0.378 0.570

Zn 0.668 0.569 0.173

As all p-values were greater than 0.05, it was concluded that the corresponding 1 value was

not significantly deviated from zero at 95% level of confidence. In other words, no

instability was observed for the test material at 20 ºC, 40 ºC and 50 ºC during the testing

period. The test material was considered fit for the purpose of the supplementary

comparison.

To monitor the highest temperature that the test material would be exposed to during the

transportation, temperature recording strips were sent along with the test material to the

participating institutes. According to the information provided by the participants in the

Sample Receipt Forms, the maximum temperatures that the test material experienced were

all below 40 ºC.

3.3. Instructions to Participants

Participants were free to choose the analytes and any analytical methods for examination.

They were advised to mix the sample thoroughly before processing. A sample size of at least

0.5 g was recommended for testing. Participants were requested to perform at least three

independent measurements on three separate portions of the sample and to determine the

mass fractions of the analytes of interest. For determination of dry mass correction, a

minimum of three separate portions (recommended size to be about 1 g each) of the sample

was recommended to be placed over anhydrous calcium sulphate (DRIERITE®) in a

desiccator at room temperature for a minimum of 10 days until reaching a constant mass.

Participants were also advised to carry out dry mass correction and analysis of the test

material at the same time.

Participants were asked to report the mean value of at least 3 independent measurements of

the mass fractions of measurands in g/g for arsenic (total), cadmium, iron and zinc on a dry

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mass basis and its associated uncertainty (combined standard uncertainty at 1 sigma level).

Participants were requested to provide (i) description of analytical methods (including

sample dissolution procedures if any); (ii) details of the uncertainty estimation (including

complete specification of the measurement equations and description of all uncertainty

sources and their typical values); and (iii) sources and purity of any reference materials used

for calibration purposes.

4. Methods of Measurement

ICP-MS, AAS and INAA were widely used by the participants. The dissolution method

mostly used was microwave assisted digestion. A summary of the methods of measurement

used by the participants is given in Table 4. The information about dry mass correction is

shown in Table 5.

Table 4. Summary of methods of measurement used by the participants

Institute Analyte Dissolution method Calibration

method

Analytical

instrument

Reference material

used for calibration

(Traceability)

INTI Fe, Zn,

As, Cd

Microwave-assisted

digestion with

closed vessel

(HNO3 + H2O2)

Fe, Zn, Cd:

External

Calibration

Curve. Linear

Regression

As: Standard

Addition

Technique

Fe, Zn: Flame AAS

As, Cd: GF-AAS

Transversal Heated

Atomizer, with

Zeeman

Background Corr.

Fe: NIST SRM 3126a

Zn: NIST SRM 3168a

As: NIST SRM 3103a

Cd: NIST SRM 3108

ANSTO Fe, Zn,

As

Not applicable k0- NAA HPGe gamma

spectrometry

IRMM-530r

INMETRO Fe, Zn,

As, Cd

Microwave-assisted

digestion

(HNO3/H2O2)

External

Calibration

Fe: ICP-AES

Zn, As, Cd:

ICP-MS

Fe: NIST SRM 3126a

Zn: NIST SRM 3168a

As: NIST SRM 3103a

Cd: NIST SRM 3108

BIM Zn Microwave-assisted

digestion (HNO3);

Thermal digestion

(HNO3/HF)

External linear

calibration

method

ICP-quadrupole

MS

170369 Zn ICP

standard traceable to

SRM from NIST

Zn(NO3)2 in HNO3

2-3%, CertiPUR

CMQ Fe, Zn,

As, Cd

Microwave-assisted

digestion

(HNO3/H2O2/HF)

Fe: Bracketing

Zn, As, Cd:

Known Addition

ICP-MS Fe: NIST SRM 3126a

(Lot 51031)

Zn: NIST SRM 3168a

(Lot 80123)

As: NIST SRM 3103a

(Lot 10713)

Cd: NIST SRM 3108

(Lot 60531)

NIM Fe, Zn,

As, Cd

Microwave-assisted

digestion

(HNO3/H2O2/HF)

Fe, Zn, Cd:

Double IDMS

As: Standard

addition method

Q-ICP-MS Fe: GBW 08616

Zn: GBW 08620

As: GBW 08667

Cd: GBW 08612

NIS Fe, Zn, Fe, Zn, Cd: 1- Dry Fe, Zn, As: Fe, Zn: Flame Fe: NIS iron certified

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method

Analytical

instrument

Reference material


(Traceability)

As, Cd ashing; 2- Digestion

by perchloric acid

and nitric acid

As: Digestion by

perchloric acid and

nitric acid

External

calibration

Cd: 1-External

calibration;

2-standard

addition

calibration

atomic absorption

spectrometer

As, Cd:

Electrothermal

atomic absorption

spectrometer

reference material

Zn: NIS Zinc certified

reference material

As: NIS Arsenic

certified reference

material

Cd: NIS Cadmium

certified reference

material

LNE Fe, As,

Cd

Microwave-assisted

digestion

(HNO3/H2O2/HF)

Fe, Cd: Double

IDMS

As: Standard

addition

Fe, As: Quad

ICP/MS + CCT

Cd: Quad ICP/MS

Fe: High purity Iron

BNM 001

As: High purity As2O5

(Alfa Aesar 99.9%)

Cd: High purity

Cadmium (Prolabo

99.9999%)

EIM Fe, Zn,

As, Cd

Microwave-assisted

digestion

(HNO3/H2O2)

Standard

additions with

internal standard

High resolution

ICP-MS

Fe: NIST SRM 3126a

Zn: NIST SRM 3168a

As: NIST SRM 3103a

Cd: NIST SRM 3108

GLHK Fe, Zn,

As, Cd

Microwave-assisted

digestion

(HNO3/H2O2/HF)

Fe, Zn, Cd:

Double IDMS

As: Gravimetric

standard addition

High resolution

ICP-MS

Fe: NIST SRM 3126a

Zn: NIST SRM 3168a

As: NIST SRM 3103a

Cd: NIST SRM 3108

NPLI Fe, Zn,

As, Cd

Microwave-assisted

digestion (HNO3 +

H2O2)

Fe, Zn, As:

Absorbance

versus

concentration of

standards

Cd: Counts per

sec. versus

concentration of

standards

Fe, Zn: F-AAS

As: GF-AAS

Cd: High Resolution

ICP-MS

Fe: NIST SRM 3126a

Zn: NIST SRM 3168a

As: NIST SRM 3103a

Cd: NIST SRM 1643e

NMIJ (1) Fe, Zn,

As, Cd

Microwave-assisted

digestion

(HNO3/H2O2/HF)

Standard addition

ICP-MS

ICP-Q-MS JCSS standard

solution

NMIJ (2) Fe, Zn,

Cd

Microwave-assisted

digestion (HNO3/

HClO4)

Double IDMS ICP-Q-MS JCSS standard

solution

KRISS Zn, As,

Cd

Zn, Cd:

Microwave-assisted

digestion

(HNO3/H2O2)

As: Not applicable

Zn, Cd: Double

IDMS

As: INAA

Zn: Magnetic

sector ICP-MS

(medium

resolution)

As: Highly pure Ge

detector

Zn: KRISS Zn

primary standard

solution

As: KRISS As

primary standard

solution

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method

Analytical

instrument

Reference material


(Traceability)

Cd: Magnetic

sector ICP-MS

(low resolution)

Cd: KRISS Cd

primary standard

solution

SIRIM Fe, Zn,

As, Cd

Microwave-assisted

digestion

(6 mL HNO3 + 1

mL HCl)

External

calibration

ICP-MS (without

isotope dilution)

Fe: NIST SRM 728

Zn: NIST SRM 728

As: NIST SRM 83

Cd: NIST SRM 728

CENAM Fe, Zn,

As, Cd

Microwave-assisted

digestion

(HNO3/H2O2/HF)

Fe, Zn, Cd: Exact

matching double

ID-ICP-SFMS

As: Internal

standard with

standard

addition-ICP-SF

MS

High resolution

ICP-SFMS

Fe: Primary reference

material: DMR-86c

iron monoelemental

aqueous solution

Zn: Primary reference

material: DMR-441

zinc monoelemental

aqueous solution

As: Reference

material used for

calibration

DMR-312b arsenic;

for internal standard

SRM-3167 yttrium

monoelemental

aqueous solution

Cd: Primary reference

material: DMR-461a

Cadmium

monoelemental

aqueous solution

HSA Fe Microwave-assisted

digestion

(HNO3/H2O2/HF)

Double IDMS ICP-MS NIST SRM 3126a

JSI (1) Fe, Zn,

As, Cd

Closed vessel

microwave-assisted

digestion

(HNO3/H2O2/HF)

External

calibration

ICP-MS Fe: NIST SRM 3126a

Zn: NIST SRM 3168a

As: NIST SRM 3103a

Cd: NIST SRM 3108

JSI (2) Fe, Zn,

As

No digestion k0-method of

INAA

TRIGA Mark II

research reactor,

absolutely

calibrated HPGe

detector

IRMM-530R

NIMT Fe, Zn,

As, Cd

Microwave-assisted

digestion

(HNO3/H2O2/HF)

Fe, Zn, Cd:

IDMS

As: Standard

Addition with Rh

as an internal

standard

ICP-QMS Fe: NIST SRM 3126a

Zn: NIST SRM 3168a

As: NIST SRM 3103a

Cd: NIST SRM 3108

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Table 5. Information reported by the participants for dry mass correction

Institute Amount and number of

sample aliquots taken for

dry mass correction

Correction for dry mass (%) Uncertainty for dry mass

correction

INTI Number of sample aliquots

taken for dry mass correction:

3

Correction for dry mass (% of

weighted sample): 84.9%

Dry Mass Factor

correction:1.1779

Uncertainty for dry mass

correction, %Urel: 2.2 (k = 2)

ANSTO 3 aliquots, from 0.99 g to 1.06

g

Moisture content 14.76 (% of

weighted sample)

Standard deviation of mean

moisture content 0.025 (% of

weighted sample)

INMETRO Amount of sample aliquots

taken for dry mass correction

= 1.45 g


weighted sample) = 0.90

(correction factor)


correction = 0.01 (k = 2)

BIM Dry mass correction was made

based on 3 samples (every

sample is about 1.0000 g).

The following results were

obtained: 86.63, 86.85 and

86.65 % of weighted sample.

Standard uncertainty = 0.002

CMQ Three portions of

approximately 0.8 grams of

sample were weighed and then

dried in a desiccator with

anhydrous calcium sulphate

(DRIERITE®) at the room

temperature for a minimum of

10 days and this procedure

was repeated until constant

weight was obtained.

Moisture (%) = 14.96 u std = 0.00009

NIM 1 g/aliquot and 3 aliquots The dry mass was the 85.2%

of the weighted sample.

The relative uncertainty was

0.1% for dry mass correction.

NIS No. of sample = 3

Weight taken = 1.01705 g,

1.00294 g, 1.00257 g

Weight loss% = 13.623,

13.842, 13.665

Uexp = 0.009864g

LNE Three aliquots of around 1g

had been taken.

Mean of the 3 aliquots:

12.75%

Standard deviation of the

mean: 0.3%

EIM Five samples (1 g portions) of

the material were dried over

DRIERITE for 30 days and

subsequently introduced in a

vacuum oven at room

temperature for 24 h.

The dry mass fraction of the

material was calculated as

0.84810.

The dry mass fraction of the

material was calculated as

0.84810 with a combined

standard uncertainty of

0.00054 and an expanded

uncertainty of 0.00108 (k = 2).

GLHK Amount: 1 g/aliquot

Number of sample aliquots: 3

Analysis of cadmium: 84.88%

of weighted sample

Analysis of iron: 84.74% of

weighted sample

Analysis of zinc: 84.74% of

weighted sample

Analysis of arsenic: 85.07%

of weighted sample

Analysis of cadmium: 0.08%

of the combined standard

uncertainty

Analysis of iron: 0.08% of the

combined standard uncertainty

Analysis of zinc: 0.25% of the

combined standard uncertainty

Analysis of arsenic: 0.02% of

the combined standard

uncertainty

NPLI Information not provided Information not provided Information not provided

NMIJ (1) 0.5 g to 1.0 g for each of the 6

sub-samples


weighted sample) = 85.13%


correction = 0.05%

NMIJ (2) 1.0 g for each of the three

sub-samples


weighted sample) = 85.78%


correction = 0.05%

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Institute Amount and number of

sample aliquots taken for

dry mass correction

Correction for dry mass (%) Uncertainty for dry mass

correction

KRISS Mass of sample taken: 1.0 g,

number of sample taken: 3

Dry mass: 84.74 % of

weighted sample


correction: 0.07%

SIRIM Three replicate of 1.0 gram of

sample was taken and placed

over anhydrous calcium

sulphate (DRIERITE®) in a

desiccator at room

temperature for a minimum of

10 days until a constant mass

is reached.

Moisture (%) = 0.59 Relative Standard uncertainty,

U(MC)/Ms = 0.0001325

CENAM Three samples of

approximately 1 g were taken.

A mean value of 15.1% of

moisture in the sample

Relative standard uncertainty

for dry mass correction:

0.073%

HSA The moisture content in the

shrimp sample was

determined from three

separate sub-samples. The

bottle was thoroughly shaken

before three sub-samples of

approximately 1.0 g each were

taken and placed over

anhydrous calcium sulphate

(DRIERITE®). The first

weighing was done after 10

days and subsequently at 7

days interval. Constant mass

was reached after 31days.

The average loss in moisture

was found to be 15.17%.

Estimate derived from drying

experiment over anhydrous

calcium sulphate

(DRIERITE®), u(FMCF) =

0.00031

JSI (1) An aliquot varied from 1.06 to

1.18 g. 4 aliquots were taken

in this study.

The dry mass obtained for

APMP.QM-S5 Seafood was

84.8228% (15.1772%

moisture content).

Expanded combined

uncertainty of the dry mass

correction = 0.15%

JSI (2) An aliquot varied from 1.06 to

1.18 g. 4 aliquots were taken

in this study.

The dry mass obtained for

APMP.QM-S5 Seafood was

84.8228% (15.1772%

moisture content).

Expanded combined

uncertainty of the dry mass

correction = 0.15%

NIMT Amount and number of

sample aliquots taken for dry

mass correction ~0.5 g

Moisture content 14.48% Taken from standard deviation

of 20 measurements divided

by √n

5. Results and Discussion

5.1. General

A total of 69 measurement results were reported for APMP.QM-S5 from 18 NMIs/DIs. The

reported results sorted in an ascending order are presented in Tables 6-9. All measurement

results were reported on a dry mass basis for comparability purposes.

of 47

Table 6. Reported results for Arsenic (total)

Institute Reported

value (g/g)

Reported

standard

uncertainty

(g/g)

Coverage

factor k

(95% level of

confidence)

Expanded

uncertainty

(g/g)

Analytical

instrument /

Method

NIS 37.2175 1.0764 2 2.1527 Electrothermal AAS

ANSTO 41.72* 0.92 2 1.84 k0-NAA

JSI (1) 42.8 0.9 2 1.8 ICP-MS

SIRIM 43.49 1.80 2 3.60 ICP-MS

INMETRO 43.9 0.45 2 0.9 ICP-MS

LNE 44 1 2 2 ICP-Q-MS + CCT

NIMT 44.6 1.1 2 2.2 ICP-Q-MS

NMIJ (1) 44.7 0.5 2 0.9 ICP-Q-MS

(standard addition)

NIM 44.7 0.7 2 1.4 ICP-Q-MS

CMQ 45.32 0.38 2 0.76 ICP-MS

CENAM 45.6 1.4 2 2.8

Internal standard +

Standard

addition-ICP-SFMS

GLHK 46.1 0.9 2 1.8 High resolution

ICP-MS

JSI (2) 47.5** 1.7 2 3.4 k0-INAA

KRISS 47.9 0.5 2.57 1.3 INAA

EIM 48.14 0.70 2 1.41 High resolution

ICP-MS

INTI 48.2 0.87 2 1.7 GF-AAS

NPLI 49.94 2.10 2.12 4.45 GF-AAS

Note:

* The result submitted by ANSTO was not included in the calculation of the supplementary

comparison reference value (SCRV). Please refer to Section 5.2 for details.

** It was agreed in the CCQM IAWG November 2011 Meeting that when more than one

value was provided by an NMI/DI, the value with the smallest uncertainty should normally

be used for the calculation of SCRV. As such, the result submitted by JSI (2) was not

included in the calculation of SCRV. Please refer to Section 5.2 for details.

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Table 7. Reported results for Cadmium

Institute Reported

value (g/g)

Reported

standard

uncertainty

(g/g)

Coverage

factor k

(95% level of

confidence)

Expanded

uncertainty

(g/g)

Analytical

instrument /

Method

JSI 0.121* 0.002 2 0.004 ICP-MS

NPLI 0.129 0.0015 2.37 0.0035 High resolution

ICP-MS

SIRIM 0.185 0.003 2 0.006 ICP-MS

LNE 0.193 0.003 2 0.006 ICP-Q-MS

INMETRO 0.200 0.004 2 0.008 ICP-MS


ICP-MS

CMQ 0.223 0.003 2 0.005 ICP-MS

NMIJ (1) 0.223 0.002 2 0.004 ICP-Q-MS

(standard addition)

NMIJ (2) 0.224** 0.002 2 0.004 ICP-Q-MS

(double IDMS)

CENAM 0.2252 0.0014 2 0.0028

IE-double

ID-ICP-SFMS (low

resolution mode)

KRISS 0.227 0.006 1.96 0.011

Magnetic sector

ICP-MS

(low resolution)

INTI 0.23 0.016 2 0.03 GF-AAS


ICP-MS

NIM 0.236 0.003 2 0.006 ICP-Q-MS

NIMT 0.255 0.005 2 0.010 ICP-Q-MS

NIS 0.7061 0.0208 2 0.0415 Electrothermal AAS

Note:

* The result submitted by JSI was not included in the calculation of the supplementary




be used for the calculation of SCRV. As such, the result submitted by NMIJ (2) was not


of 47

Table 8. Reported results for Iron

Institute Reported value

(g/g)

Reported

standard

uncertainty

(g/g)

Coverage

factor k (95%

level of

confidence)

Expanded

uncertainty

(g/g)

Analytical

instrument /

Method

SIRIM 155.98 4.80 2 9.61 ICP-MS

ANSTO 159.9* 2.8 2 5.6 k0-NAA

NIS 169.0934 4.8060 2 9.6120 Flame AAS


ICP-MS

CMQ 175.1 1.6 2 3.2 ICP-MS

NIMT 176 3 2 6 ICP-Q-MS

JSI (2) 177** 6 2 12 k0-INAA

JSI (1) 179 2 2 4 ICP-MS

INMETRO 179.4 3.75 2 7.5 ICP-AES

NMIJ (2) 180.2** 4.5 2 9.0 ICP-Q-MS

(double IDMS)

NMIJ (1) 183.5 1.8 2 3.5

ICP-Q-MS

(standard

addition)

NIM 183.8 2.2 2 4.4 ICP-Q-MS

HSA 184.96 4.88 2 9.76 ICP-MS

LNE 185 3.5 2 7 Quard ICP/MS

+ CCT

NPLI 186.58 2.73 2.45 6.70 Flame AAS


ICP-MS

CENAM 189 5.5 2 11

Double

ID-ICP-SFMS

(medium

resolution mode)

INTI 194 7.3 2 15 Flame AAS

Note:





be used for the calculation of SCRV. As such, the results submitted by JSI (2) and NMIJ (2)

were not included in the calculation of SCRV. Please refer to Section 5.2 for details.

of 47

Table 9. Reported results for Zinc

Institute Reported

value (g/g)

Reported

standard

uncertainty

(g/g)

Coverage

factor k

(95% level

of

confidence)

Expanded

uncertainty

(g/g)

Analytical instrument

/ Method

SIRIM 48.53 0.66 2 1.33 ICP-MS

ANSTO 51.47* 0.90 2 1.80 k0-NAA

NIS 54.9669 1.4142 2 2.8285 Flame AAS

INMETRO 56.8 1.2 2 2.4 ICP-MS

BIM 57.9* 1.7 2 3.4 ICP-Q-MS

INTI 58.5 1.6 2 3.3 Flame AAS

NIMT 58.6 0.9 2 1.8 ICP-Q-MS

JSI (2) 58.9** 1.6 2 3.2 k0-INAA

NMIJ (1) 59.5 0.8 2 1.5 ICP-Q-MS (standard

addition)

NMIJ (2) 59.8** 1.7 2 3.4 ICP-Q-MS

(double IDMS)

JSI (1) 59.9 0.9 2 1.8 ICP-MS


ICP-MS

CMQ 60.22 0.74 2 1.48 ICP-MS

CENAM 60.3 2.0 2 4.1

IE-double

ID-ICP-SFMS (medium

resolution mode)

KRISS 60.30 0.86 1.97 1.68

Magnetic sector

ICP-MS

(medium resolution)

NIM 60.8 0.5 2 1.0 ICP-Q-MS

EIM 61.72 1.11 2 2.22

High resolution

ICP-MS

NPLI 73.13 1.57 2.45 3.85 Flame AAS

Note:

* The results submitted by ANSTO and BIM were not included in the calculation of the

supplementary comparison reference value (SCRV). Please refer to Section 5.2 for details.





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5.2. Calculation of the reference mass fraction values and associated uncertainties

In order to establish the degrees of equivalence (DoE) of the measurement results submitted

by the participants of APMP.QM-S5, a supplementary comparison reference value (SCRV)

was calculated for each measurand as a consensus value of the reported results [2]. It was

agreed in the CCQM IAWG November 2011 Meeting that when more than one value was

provided by an NMI/DI, the value with the smallest uncertainty should normally be used for

this purpose as the key comparison reference value (KCRV)/SCRV is supposed to be the

best estimate of the true value. Moreover, all submitted results should be included in the

comparison report and a DoE calculated for each one.

As a follow-up to the discussions on the Draft A Report at the CCQM IAWG Meeting held

on 16-17 April 2012, participants were formally requested to review their own results and

inform the coordinating laboratory, together with reasons, if they identify any measurement

problems which could explain an error on the reported results.

Further to its verbal report at the CCQM IAWG meeting, ANSTO (Australia) informed the

coordinator on 24 April 2012 that their results (As, Fe and Zn) should be excluded from all

analyses of data on technical grounds with the reasons stated as follows:

ANSTO has reported that a mistake was made in its calculation of iron, zinc and total arsenic

concentration. The mistake was due to a false assumption about the sample/detector

geometry, related to the core capability ‘Corrections for sample and standard geometry

differences’. The ANSTO values should be excluded from all analyses, including the

calculation of the SCRV, on the technical ground that the values are known to be

incorrect. Recalculation using the correct method results in the following values for

concentration and standard uncertainty (µg/g): iron 183 ± 3; zinc 58.9 ± 1.0; total arsenic

45.3 ± 1.0.

Further to its verbal report at the CCQM IAWG meeting, JSI (Slovenia) notified the

coordinator on 27 April 2012 that a transcription error on the result of Cd was found. The

details are shown as follows:

After careful evaluation of the discrepancy in the result obtained by the participating

laboratories and the reported value that provided JSI for the analysis of Cd in Seafood, we

found out that the mistake appeared during the transcription of the results in the final stage.

The actual determined value for Cd in seafood was 0.203 ± 0.004 mg/kg. We regret that we

made a mistake and did not report the correct result for Cd.

of 47

On 7 June 2012, BIM (Bulgaria) reported to the coordinator that the Zn standard solution

(1000 mg/L) which used was used directly for calibration purpose was purchased from a

commercial supplier. The traceability of the Zn standard solution did not comply with the

requirements as stated in the CIPM MRA document “Traceability in CIPM MRA” [3]. The

details are shown as follows:

Our results were not obtained against a SRM issued by an NMI, but with the aid of the Zinc

standard mentioned.

In this regard, the measurement results reported by ANSTO (As, Fe and Zn), JSI (Cd) and

BIM (Zn) were excluded on technical grounds in the calculation of SCRV.

The measurement results that were included in the calculation of SCRV are shown in Tables

6-9. The measurement results there were excluded with technical reasons in the calculation

of SCRV are also provided in the same tables. The consensus values and their dispersion of

the valid participants’ results using the following three different statistical quantifiers are

shown in Table 10.

Arithmetic mean and standard deviation

Median and MADe [median absolute deviation (MAD) multiplied by 1.483]

Mixture model median (MM-median) and standard deviation of MM-median [4]

Table 10. Results of various consensus values and their dispersion (unit: g/g)

Measurand Arithmetic

mean

Standard

deviation Median MADe

MM-

median

S(MM-

median)

As 45.1 3.0 44.7 1.8 45.1 2.6

Cd 0.249 0.135 0.224 0.016 0.224 0.026

Fe 179.9 9.6 183.5 6.7 181.4 8.4

Zn 59.5 5.1 60.0 1.6 59.7 2.2

As depicted in Table 10, the following findings were observed:

A good agreement was observed among the consensus values calculated as the

arithmetic mean, median and MM-median for As, Fe and Zn.

For the measurand of Cd, there was a good agreement between the consensus values

calculated as the median and MM-median.

It is noted that the arithmetic mean is not robust to the presence of extreme values. As such,

this statistical quantifier is not recommended to be used as the estimation of SCRV. Given

that each of the participants gives a reliable estimate of measurement uncertainty, the

of 47

MM-median is a robust estimator of SCRV and accounts for the reported uncertainty of each

participant. On the other hand, the median is a simple and robust estimator of SCRV and

does not require the participants’ uncertainties for calculation.

GLHK, as the coordinating laboratory of APMP.QM-S5, presented the results and their

dispersion as shown in Table 10 at the CCQM IAWG Meeting held on 9-11 October 2012.

For APMP.QM-S5, the two statistical approaches, MM-median and median, gave similar

values for SCRV. To this end, the median and the standard uncertainty derived from MADe

were recommended to be the SCRV and u(SCRV) resepectively. The standard uncertainty

derived from MADe was calculated using the equation (3), where n is the number of

participants’ results included in the calculation. Following the CCQM Guidance Note [2],

the supplementary comparison expanded uncertainty was calculated as U(SCRV) = 2

u(SCRV). The calculated SCRV, u(SCRV) and U(SCRV) are summarized in Table 11.

nu

MADe25.1(SCRV) (3)

Table 11. Calculated SCRV, u(SCRV) and U(SCRV)

Measurand SCRV u(SCRV) U(SCRV) U(SCRV)

As 44.7 g/g 0.58 g/g 1.2 g/g 2.6%

Cd 0.224 g/g 0.0054 g/g 0.011 g/g 4.8%

Fe 183.5 g/g 2.15 g/g 4.3 g/g 2.3%

Zn 60.0 g/g 0.54 g/g 1.1 g/g 1.8%

For ease of reference, the measurement results of the APMP.QM-S5 are presented in Figures

1-4 with the respective proposed SCRV (as median) and u(SCRV). The solid horizontal line

in red is the proposed SCRV and the dashed lines show the standard uncertainty of the

proposed reference value, u(SCRV). The error bar line of an individual participant’s result

covers the reported result standard uncertainty.

of 47

Figure 1. APMP.QM-S5: Participants’ reported results and measurement uncertainties

for Arsenic (total) (unit: g/g)

■ AAS ▲ NAA ♦ ICP-MS ● HR-ICP-MS

Note: Participants' results are displayed with error bars representing reported standard

uncertainties. The solid horizontal line in red is the proposed SCRV (as median) and the

dashed lines show the standard uncertainty of the proposed reference value, u(SCRV). The

results submitted by ANSTO and JSI (2) were not included in the calculation of SCRV.

Please refer to Section 5.2 for details.

of 47

Figure 2. APMP.QM-S5: Participants reported results and measurement uncertainties

for Cadmium (unit: g/g)

■ AAS ♦ ICP-MS ● HR-ICP-MS

IDMS




results submitted by JSI and NMIJ (2) were not included in the calculation of SCRV. Please

refer to Section 5.2 for details.

0.7061

of 47


for Iron (unit: g/g)

■ AAS ▲ NAA ♦ ICP-MS ICP-AES ● HR-ICP-MS

IDMS




results submitted by ANSTO, JSI (2) and NMIJ (2) were not included in the calculation of

SCRV. Please refer to Section 5.2 for details.

of 47


for Zinc (unit: g/g)

■ AAS ▲ NAA ♦ ICP-MS ● HR-ICP-MS

IDMS




results submitted by ANSTO, BIM, JSI (2) and NMIJ (2) were not included in the

calculation of SCRV. Please refer to Section 5.2 for details.

of 47

5.3. Equivalence statements

According to the CCQM Guidance Note [2], the degree of equivalence (DoE) and its

uncertainty of a measurement result reported by a participating NMI/DI with respect to the

SCRV can be calculated using the following equations (4)-(5):

) SCRV( ii xd (4)

22 )SCRV()(2)( uxudU ii (5)

where

xi is the reported value from the ith

participant (i = 1 to n);

di is the difference between the reported value and the SCRV; and

U(di) is the expanded uncertainty (k = 2) of the difference di at a 95% level of confidence.

It is possible for the values of di and U(di) published in this report to differ slightly from the

values of di and U(di) that can be calculated using the equations given in (4)-(5). These

differences arise from the necessary rounding of the SCRV and u(SCRV) prior to their

publication in Tables 12 to 15. The relative values of di and U(di) are expressed as percent of

SCRV. The equivalence statements for APMP.QM-S5 based on the proposed SCRV are

given in Tables 12-15 and are shown graphically in Figures 5-8.

of 47

Table 12. APMP.QM-S5: Equivalence Statement for Arsenic (total) based on the use

of median as the robust estimation of SCRV

Institute

Reported

value, xi

(g/g)

Reported

standard

uncertainty,

u(xi)

(g/g)

Difference

from SCRV, di

(g/g)

U(di)

(g/g) )( i

i

dU

d

di

relative

value

(%)

U(di)

relative

value

(%)

NIS 37.2175 1.0764 -7.48 2.44 -3.06 -16.74 5.47

ANSTO 41.72* 0.92 -2.98 2.17 -1.37 -6.67 4.86

JSI (1) 42.8 0.9 -1.90 2.14 -0.89 -4.25 4.79

SIRIM 43.49 1.80 -1.21 3.78 -0.32 -2.71 8.46

INMETRO 43.9 0.45 -0.80 1.47 -0.55 -1.79 3.28

LNE 44 1 -0.70 2.31 -0.30 -1.57 5.17

NIMT 44.6 1.1 -0.10 2.49 -0.04 -0.22 5.56

NMIJ 44.7 0.5 0.00 1.53 0.00 0.00 3.42

NIM 44.7 0.7 0.00 1.82 0.00 0.00 4.06

CMQ 45.32 0.38 0.62 1.39 0.45 1.39 3.10

CENAM 45.6 1.4 0.90 3.03 0.30 2.01 6.78

GLHK 46.1 0.9 1.40 2.14 0.65 3.13 4.79

JSI (2) 47.5** 1.7 2.80 3.59 0.78 6.26 8.04

KRISS 47.9 0.5 3.20 1.53 2.09 7.16 3.42

EIM 48.14 0.70 3.44 1.82 1.89 7.70 4.06

INTI 48.2 0.87 3.50 2.09 1.67 7.83 4.68

NPLI 49.94 2.10 5.24 4.36 1.20 11.72 9.75

Note:





be used for the calculation of SCRV. As such, the result submitted by JSI (2) was not


of 47

Table 13. APMP.QM-S5: Equivalence Statement for Cadmium based on the use of

median as the robust estimation of SCRV

Institute

Reported

value, xi

(g/g)

Reported

standard

uncertainty,

u(xi)

(g/g)

Difference

from SCRV, di

(g/g)

U(di)

(g/g) )( i

i

dU

d

di

relative

value

(%)

U(di)

relative

value

(%)

JSI 0.121* 0.002 -0.103 0.012 -8.954 -46.01 5.14

NPLI 0.129 0.0015 -0.095 0.011 -8.486 -42.44 5.00

SIRIM 0.185 0.003 -0.039 0.012 -3.165 -17.45 5.51

LNE 0.193 0.003 -0.031 0.012 -2.518 -13.88 5.51

INMETRO 0.200 0.004 -0.024 0.013 -1.793 -10.75 6.00

GLHK 0.220 0.006 -0.004 0.016 -0.254 -1.83 7.20

CMQ 0.223 0.003 -0.001 0.012 -0.089 -0.49 5.51

NMIJ (1) 0.223 0.002 -0.001 0.012 -0.096 -0.49 5.14

NMIJ (2) 0.224** 0.002 0.000 0.012 -0.009 -0.04 5.14

CENAM 0.2252 0.0014 0.001 0.011 0.099 0.49 4.98

KRISS 0.227 0.006 0.003 0.016 0.180 1.29 7.20

INTI 0.23 0.016 0.006 0.034 0.175 2.63 15.07

EIM 0.234 0.005 0.010 0.015 0.673 4.42 6.57

NIM 0.236 0.003 0.012 0.012 0.963 5.31 5.51

NIMT 0.255 0.005 0.031 0.015 2.100 13.79 6.57

NIS 0.7061 0.0208 0.482 0.043 11.215 215.08 19.18

Note:

* The result submitted by JSI was not included in the calculation of the supplementary




be used for the calculation of SCRV. As such, the result submitted by NMIJ (2) was not


of 47

Table 14. APMP.QM-S5: Equivalence Statement for Iron based on the use of median

as the robust estimation of SCRV

Institute

Reported

value, xi

(g/g)

Reported

standard

uncertainty,

u(xi)

(g/g)

Difference

from SCRV, di

(g/g)

U(di)

(g/g) )( i

i

dU

d

di

relative

value

(%)

U(di)

relative

value

(%)

SIRIM 155.98 4.80 -27.52 10.52 -2.62 -15.00 5.73

ANSTO 159.9* 2.8 -23.60 7.06 -3.34 -12.86 3.85

NIS 169.0934 4.8060 -14.41 10.53 -1.37 -7.85 5.74

EIM 169.84 3.19 -13.66 7.70 -1.77 -7.44 4.19

CMQ 175.1 1.6 -8.40 5.37 -1.57 -4.58 2.92

NIMT 176 3 -7.50 7.39 -1.02 -4.09 4.02

JSI (2) 177** 6 -6.50 12.75 -0.51 -3.54 6.95

JSI (1) 179 2 -4.50 5.88 -0.77 -2.45 3.20

INMETRO 179.4 3.75 -4.10 8.65 -0.47 -2.23 4.71

NMIJ (2) 180.2** 4.5 -3.30 9.98 -0.33 -1.80 5.44

NMIJ (1) 183.5 1.8 0.00 5.61 0.00 0.00 3.06

NIM 183.8 2.2 0.30 6.16 0.05 0.16 3.36

HSA 184.96 4.88 1.46 10.67 0.14 0.80 5.81

LNE 185 3.5 1.50 8.22 0.18 0.82 4.48

NPLI 186.58 2.73 3.08 6.95 0.44 1.68 3.79

GLHK 186.9 5.5 3.40 11.81 0.29 1.85 6.44

CENAM 189 5.5 5.50 11.81 0.47 3.00 6.44

INTI 194 7.3 10.50 15.22 0.69 5.72 8.30

Note:







of 47

Table 15. APMP.QM-S5: Equivalence Statement for Zinc based on the use of median


Institute

Reported

value, xi

(g/g)

Reported

standard

uncertainty,

u(xi)

(g/g)

Difference

from SCRV, di

(g/g)

U(di)

(g/g) )( i

i

dU

d

di

relative

value

(%)

U(di)

relative

value

(%)

SIRIM 48.53 0.66 -11.42 1.71 -6.67 -19.05 2.86

ANSTO 51.47* 0.90 -8.48 2.10 -4.03 -14.15 3.51

NIS 54.9669 1.4142 -4.98 3.03 -1.64 -8.31 5.06

INMETRO 56.8 1.2 -3.15 2.64 -1.20 -5.25 4.40

BIM 57.9* 1.7 -2.05 3.57 -0.57 -3.42 5.96

INTI 58.5 1.6 -1.45 3.38 -0.43 -2.42 5.64

NIMT 58.6 0.9 -1.35 2.10 -0.64 -2.25 3.51

JSI (2) 58.9** 1.6 -1.05 3.38 -0.31 -1.75 5.64

NMIJ (1) 59.5 0.8 -0.45 1.94 -0.23 -0.75 3.23

NMIJ (2) 59.8** 1.7 -0.15 3.57 -0.04 -0.25 5.96

JSI (1) 59.9 0.9 -0.05 2.10 -0.02 -0.08 3.51

GLHK 60.0 1.0 0.05 2.28 0.02 0.08 3.80

CMQ 60.22 0.74 0.27 1.84 0.15 0.45 3.07

CENAM 60.3 2.0 0.35 4.15 0.08 0.58 3.40

KRISS 60.30 0.86 0.35 2.04 0.17 0.58 6.92

NIM 60.8 0.5 0.85 1.48 0.57 1.42 2.47

EIM 61.72 1.11 1.77 2.47 0.72 2.95 4.13

NPLI 73.13 1.57 13.18 3.32 3.97 21.98 5.54

Note:

* The results submitted by ANSTO and BIM were not included in the calculation of the

supplementary comparison reference value (SCRV). Please refer to Section 5.2 for details.





of 47

Figure 5. APMP.QM-S5: Equivalence Statement for Arsenic (total) based on the use

of median as the robust estimation of SCRV

Note: The half of each bar indicates U(di), relative value (%).

of 47

Figure 6. APMP.QM-S5: Equivalence Statement for Cadmium based on the use of

median as the robust estimation of SCRV


of 47

Figure 7. APMP.QM-S5: Equivalence Statement for Iron based on the use of median



of 47

Figure 8. APMP.QM-S5: Equivalence Statement for Zinc based on the use of median



of 47

6. Demonstration of Core Capabilities

As agreed in previous CCQM IAWG meetings, a system of Core-Capabilities for inorganic

analysis will be employed in key/supplementary comparisons starting from CCQM-K75

onward. This strategy is to improve the efficiency and effectiveness of key/supplementary

comparisons to support CMC claims. With the use of the system, new CMC claims can be

supported by describing core capabilities that are required to deliver the claimed

measurement service and by referencing core capabilities that were successfully

demonstrated by participation in relevant key/supplementary comparisons. In this

connection, all participants were requested to submit their Inorganic Core Capabilities (CCs)

Tables to the coordinator for compilation. The returns are summarized in the Appendix.

7. Conclusion

Generally, the participants’ results of APMP.QM-S5 were found consistent for all

measurands according to their equivalence statements. Except with some extreme values,

most of the participants obtained the values of di/U(di) within 1 for the measurands.

For sample dissolution, except those participants using INAA as the measurement technique,

most of the participants used microwave acid digestion methods. For the instrumental

determination, a variety of techniques like ICP-MS, ICP-OES, INAA and AAS were

employed by the participants.

of 47

Acknowledgement

The contributions from the contract persons and/or analysts of participating NMIs/DIs, as

listed below, are highly appreciated and acknowledged.

Institute Contact person and/or analysts

INTI Liliana Valiente ANSTO John W. Bennett INMETRO Rodrigo Caciano de Sena BIM Boriana Kotzeva CMQ Gabriela Massiff NIM Jingbo Chao, Jun Wang

NIS Randa Nasr Ahmed Yamani LNE Guillaume Labarraque EIM Elias Kakoulidis, Eugenia Lampi GLHK Yiu-chung Yip NPLI Shankar Gopala Aggarwal, Prabhat K. Gupta NMIJ Yanbei Zhu, Shin-ichi Miyashita

KRISS Yong-Hyeon Yim SIRIM Osman Zakaria, Norliza Baharom

CENAM Francisco Javier Matehuala Sánchez, EdithValle Moya, Maria del Rocio Arvizu Torres, Judith Velina Lara Manzano

HSA Richard Shin JSI Milena Horvat, Tea Zuliani, Radmila Milacic, Radojko Jacimovic

NIMT Charun Yafa, Pranee Phukphatthanachai, Sutthinun Taebunpakul, Nattikarn Kaewkhomdee

The coordinating laboratory would like to thank Dr. Mike Sargent for providing guidance

throughout the course of this study.

References

1. International Standards Organization, ISO Guide 35: Reference materials – General and

statistical principles for certification, Geneva, Switzerland, 2006.

2. CCQM Guidance Note: Estimation of a consensus KCRV and associated degrees of

equivalence, Version 6, 2010.

3. CIPM MRA Document: Traceability in CIPM MRA, Document No.: CIPM 2009-24,

Latest update: Revised 13 October 2009.

4. D. Duewer: A Robust Approach for the Determination of CCQM Key Comparison

Reference Values and Uncertainties.

of 47

Appendix Inorganic Core Capabilities Table

APMP Supplementary Comparison: APMP.QM-S5 Institutes: BIM, CENAM, CMQ, EIM, GLHK, INMETRO, JSI, LNE, NIM, NIMT,

NMIJ, NPLI, SIRIM Method: ICP-MS (without isotope dilution) Analytes: As, Cd, Fe, Zn

Capabilities/Challenges Not tested Tested Specific challenges

encountered

Contamination control and correction

All techniques and procedures employed to reduce

potential contamination of samples as well as blank

correction procedures. The level of difficulty is greatest

for analytes that are environmentally ubiquitous and also

present at very low concentrations in the sample.

BIM, CENAM,

CMQ, EIM,

GLHK,

INMETRO, JSI,

LNE, NIM,

NIMT, NMIJ,

NPLI, SIRIM

BIM: For every experiment, two

or three separated blank samples

were measured. The blank

samples were undergone

through all analytical procedure

stages and contain all reagents,

without a sample itself.

NIM: The blank of As is low, the

contamination of sample

preparation is ignorable.

SIRIM: Preparation of sample

was handling in clean room.

Mineral acid used was Trace

selects type, it used for

digestion.

Digestion/dissolution of organic matrices

All techniques and procedures used to bring a sample

that is primarily organic in nature into solution suitable

for liquid sample introduction to the ICP.

BIM, CENAM,

CMQ, EIM,

GLHK,

INMETRO, JSI,

LNE, NIM,

NIMT, NMIJ,

NPLI, SIRIM

BIM:

1. Weighing of about 0.5 g

sample into a microwave vessel.

2. Addition of 10 ml nitric acid.

Preparation of procedural

blanks.

3. Cold predigesting for 4 hours.

4. Microwave digestion under

operating conditions

(temperature program and

pressure control).

5. Sample and standards

dilution; all solutions are

gravimetrically prepared.

CENAM: Pre-digestion and

digestion procedure were

applied to avoid high pressure in

the vessels due the biological

sample, also it is necessary to

use HF which was added during

an additional open digestion in

order to remove the silicon.

NIM: The sample was

completely digested with

of 47


encountered

HNO3/H2O2/HF in PTFE vessel.

SIRIM: Used microwave

digestion method and samples

completely dissolve. Used

HNO3, HCL, and H2O2.

Digestion/dissolution of inorganic matrices

All techniques and procedures used to bring a sample

that is primarily inorganic in nature into solution

suitable for liquid sample introduction to the ICP.

CENAM, GLHK,

INMETRO, LNE,

NIMT, NMIJ,

SIRIM

SIRIM: Used microwave

digestion method and samples

completely dissolve. Used

HNO3, HCl, and H2O2.

Volatile element containment

All techniques and procedures used to prevent the loss of

potentially volatile analyte elements during sample

treatment and storage.

CENAM, CMQ,

GLHK,

INMETRO, JSI,

NIM, NIMT,

NMIJ, NPLI,

SIRIM

CENAM and NIM: Closed

PTFE vessel used to prevent the

loss of As during sample

treatment.

SIRIM: When used microwave

digester the possibility element

lost is less.

Pre-concentration

Techniques and procedures used to increase the

concentration of the analyte introduced to the ICP.

Includes evaporation, ion-exchange, extraction,

precipitation procedures, but not vapor generation

procedures.

NIMT, NMIJ NIM: We did not use

pre-concentration procedure.

Vapor generation

Techniques such as hydride generation and cold vapor

generation used to remove the analyte from the sample as

a gas for introduction into the ICP.

NIMT, NMIJ NIM: We did not use vapor

generation method.

Matrix separation

Techniques and procedures used to isolate the analyte(s)

from the sample matrix to avoid or reduce interferences

caused by the matrix. Includes ion-exchange, extraction,

precipitation procedures, but not vapor generation

procedures. Techniques and procedures used to isolate

the analyte(s) from the sample matrix to avoid or reduce

interferences caused by the matrix. Includes

ion-exchange, extraction, precipitation procedures, but

not vapor generation procedures.

NIM, NIMT,

NMIJ

NIM: Standard addition method

was used to avoid matrix

interference.

Calibration of analyte concentration

The preparation of calibration standards and the strategy

for instrument calibration. Includes external calibration

and standard additions procedures.

BIM, CENAM,

EIM, GLHK,

INMETRO, JSI,

LNE, NIM,

NIMT, NMIJ,

NPLI, SIRIM

BIM: External linear calibration.

CENAM and EIM: standard

additions with internal std.

LNE: Dissolution of As2O5.

NIM: We used As(V) standard

solution to prepare calibration

standards, and a comparison was

made with As(III) considering

the sensitivity differences.

SIRIM: The preparation of

calibration standard is by

of 47


encountered

weight.

Signal detection

The detection and recording of the analyte isotope

signals. The degree of difficulty increases for analytes

present at low concentrations, of low isotopic abundance,

or that are poorly ionized.

BIM, CENAM,

EIM, GLHK,

INMETRO, JSI,

LNE, NIM,

NIMT, NMIJ,

SIRIM

NIM: The background of As is

not high.

SIRIM: The Detection limit of

the ICPMS is very low.

Memory effect

Any techniques used to avoid, remove or reduce the

carry-over of analyte between consecutively measured

standards and/or samples.

CENAM, EIM,

GLHK, JSI,

NIM, NIMT,

NMIJ, NPLI,

SIRIM

CENAM: Before and after

analysis, rinse with 2 %

HNO3and pure water.

NIM: As have low memory

effect.

SIRIM: For the Teflon tube,

after it use for digestion, it was

immersed in 10% HNO3 for one

day and rinse with pure water.

For the analysis, before and after

analysis, rinse with 3% HNO3

and pure water.

Correction or removal of isobaric/polyatomic

interferences

Any techniques used to remove, reduce, or

mathematically correct for interferences caused by mass

overlap of analyte isotopes with isobaric or polyatomic

species. Includes collision cell techniques, high

resolution mass spectrometry, or chemical separations.

The relative concentrations and sensitivities of the

analyte isotopes and the interfering species will affect the

degree of difficulty.

BIM, CENAM,

CMQ, EIM,

GLHK, JSI,

LNE, NIM,

NIMT, NMIJ,

NPLI, SIRIM

CENAM: In order to reduce the

polyatomic interference of 40Ar35Cl, it was used high

resolution mode, this affect the

sensitivity in the instrument for

As isotope and the degree of

difficulty in the instrumental

optimization.

CMQ: Interferences for Zn

(CaO, KO) and Fe (ArMg) were

minimized using reaction cell

(He).

EIM: HR-MS

JSI: Reaction/collision cell.

Reaction gas applied was He.

LNE: Use of CCT to remove

ArCl interference.

NIM: We used collision reaction

cell technology to reduce the

interference from matrix.

NMIJ: Interference of 40Ar16O

with the measurement of 56Fe

was removed by high-energy

collision gas.

SIRIM: We used collision cell,

He mode to remove the

of 47


encountered

interference.

Correction or removal of matrix-induced

signal suppression or enhancement

Chemical or instrumental procedures used to avoid or

correct for matrix-induced signal suppression or

enhancement.

BIM, CENAM,

CMQ, GLHK,

JSI, LNE, NIM,

NIMT, NMIJ,

NPLI

BIM: Sufficient dilution of the

samples.

CENAM: In order to reduce the

polyatomic interference of 40Ar35Cl, it was used high

resolution mode, this affects the

sensitivity in the instrument for

As isotope and the degree of

difficulty in the instrumental

optimization.

CMQ: Measurements carried out

using Standard Additions

method.

NIM: Standard addition method

used to avoid matrix

interference.

Detector deadtime correction

Measurement of, and correction for, ion detector

deadtime. Importance increases in situations where high

ion count rates are encountered.

BIM, EIM,

GLHK, LNE,

NIM, NIMT,

NMIJ, NPLI

BIM: Default detector dead time

correction was used.

NIM: The ICP-MS instrument

does dead time correction

automatically.

Mass bias/fractionation control and correction

Techniques used to determine, monitor, and correct for

mass bias/fractionation.

BIM, EIM,

INMETRO,

NIMT, NMIJ,

SIRIM

BIM: Obligatory preliminary

every-day mass calibration using

tuning solution.

SIRIM: Spike the standard into

the sample, %recovery is

80-120%.

of 47

Inorganic Core Capabilities Table

APMP Supplementary Comparison: APMP.QM-S5 Institute/Laboratory: INMETRO Method: ICP-OES Analytes: Fe


encountered


All techniques and procedures employed to reduce potential

contamination of samples as well as blank correction

procedures. The level of difficulty is greatest for analytes that

are environmentally ubiquitous and also present at very low

concentrations in the sample.

INMETRO


All techniques and procedures used to bring a sample that is

primarily organic in nature into solution suitable for liquid

sample introduction to the ICP.

INMETRO



primarily inorganic in nature into solution suitable for liquid

sample introduction to the ICP.

INMETRO



potentially volatile analyte elements during sample treatment

and storage.

INMETRO

Pre-concentration

Techniques and procedures used to increase the concentration

of the analyte introduced to the ICP. Includes evaporation,

ion-exchange, extraction, precipitation procedures, but not

vapor generation procedures.

INMETRO

Vapor generation

Techniques such as hydride generation and cold vapor

generation used to remove the analyte from the sample as a

gas for introduction into the ICP.

INMETRO

Matrix separation

Techniques and procedures used to isolate the analyte(s) from

the sample matrix to avoid or reduce interferences caused by

the matrix. Includes ion-exchange, extraction, precipitation

procedures, but not vapor generation procedures , but not

vapor generation procedures. Techniques and procedures

used to isolate the analyte(s) from the sample matrix to avoid

or reduce interferences caused by the matrix. Includes

ion-exchange, extraction, precipitation procedures, but not

vapor generation procedures.

INMETRO


The preparation of calibration standards and the strategy for

instrument calibration. Includes external calibration and

standard additions procedures.

INMETRO

Signal detection

The detection and recording of the analyte signals. The degree

INMETRO

of 47


encountered

of difficulty increases for analytes present at low

concentrations, or that are have weak emission lines.

Memory effect

Any techniques used to avoid, remove or reduce the carry-over

of analyte between consecutively measured standards and/or

samples.

INMETRO

Complex spectral backgrounds

Any techniques used to remove, reduce, or mathematically

correct for interferences caused by the overlap of analyte

emission lines with atomic, ionic, or molecular emission from

matrix components. The relative concentrations and

sensitivities of the analyte and the interfering species will

affect the degree of difficulty. Samples containing high

concentration matrix components with large numbers of

emission lines or molecular bands may increase the

measurement challenge.

INMETRO

Correction or removal of matrix-induced signal

suppression or enhancement

Chemical or instrumental procedures used to avoid or correct

for matrix-induced signal suppression or enhancement. High

concentrations of acids, dissolved solids, or easily ionized

elements will increase the degree of difficulty.

INMETRO

of 47

Inorganic Core Capabilities Table APMP Supplementary Comparison: APMP.QM-S5 Institutes: CENAM, GLHK, HSA, KRISS, LNE, NIM, NIMT, NMIJ Method: ID-ICP-MS Analytes: Cd, Fe, Zn


encountered


All techniques and procedures employed to reduce

potential contamination of samples as well as

blank correction procedures. The level of difficulty

is greatest for analytes that are environmentally

ubiquitous and also present at very low


CENAM,

GLHK, HSA,

KRISS, LNE,

NIM, NIMT,

NMIJ

NIM: The blank of Zn and Cd is low,

but the Fe maybe came from

environment.

Digestion/dissolution of organic

matrices

All techniques and procedures used to bring a

sample that is primarily organic in nature into

solution suitable for liquid sample introduction to

the ICP.

CENAM,

GLHK, HSA,

KRISS, LNE,

NIM, NIMT,

NMIJ

NIM: The HNO3/H2O2/HF can digest

shrimp powder easily and completely.

Digestion/dissolution of inorganic

matrices

All techniques and procedures used to bring a

sample that is primarily inorganic in nature into

solution suitable for liquid sample introduction to

the ICP.

GLHK, HSA,

KRISS, LNE,

NIMT, NMIJ

HSA: Sample digestion requires HF

acid for complete dissolution.

NIMT: Need to use HF to obtain

complete digestion for Fe analysis.


All techniques and procedures used to prevent the

loss of potentially volatile analyte elements during

sample treatment and storage.

GLHK, HSA,

LNE, NIM,

NIMT, NMIJ

NIM: Fe, Zn and Cd are not volatile

elements.

Pre-concentration

Techniques and procedures used to increase the

concentration of the analyte introduced to the

ICP. Includes evaporation, ion-exchange,

extraction, precipitation procedures, but not vapor

generation procedures.

NIMT, NMIJ NIM: We did not use pre-concentration

procedure.

Vapor generation

Techniques such as hydride generation and cold

vapor generation used to remove the analyte from

the sample as a gas for introduction into the ICP.

NIMT, NMIJ NIM: We did not use vapor generation

method.

Matrix separation

Techniques and procedures used to isolate the

analyte(s) from the sample matrix to avoid or

reduce interferences caused by the matrix.

Includes ion-exchange, extraction, precipitation

procedures, but not vapor generation procedures.

Techniques and procedures used to isolate the

analyte(s) from the sample matrix to avoid or

reduce interferences caused by the matrix.

CENAM, NIMT,

NMIJ

CENAM: It was applied anion

exchange method separation for Zn and

Cd

NIM: We did not separate Fe, Zn and

Cd from matrix, but diluted the samples

to avoid matrix interference before

determination.

of 47


encountered

Includes ion-exchange, extraction, precipitation


Spike equilibration with sample

The mixing and equilibration of the enriched

isotopic spike with the sample.

CENAM,

GLHK, HSA,

KRISS, LNE,

NIM, NIMT,

NMIJ

NIM: The sample was completely

digested with HNO3/H2O2/HF in PTFE

vessel.

Signal detection

The detection and recording of the analyte isotope

signals. The degree of difficulty increases for

analytes present at low concentrations, of low

isotopic abundance, or that are poorly ionized.

CENAM,

GLHK, HSA,

KRISS, LNE,

NIM, NIMT,

NMIJ

NIM: The background of Zn and Cd is

not high. The degree of difficulty

increases for low concentration of Cd

and relatively high Fe background for

Fe determination.

Memory effect

Any techniques used to avoid, remove or reduce

the carry-over of analyte between consecutively

measured standards and/or samples.

GLHK, HSA,

NIM, NIMT,

NMIJ

NIM: Three elements have low memory

effect.

Correction or removal of

isobaric/polyatomic interferences

Any techniques used to remove, reduce, or

mathematically correct for interferences caused

by mass overlap of analyte isotopes with isobaric

or polyatomic species. Includes collision cell

techniques, high resolution mass spectrometry, or

chemical separations. The relative concentrations

and sensitivities of the analyte isotopes and the

interfering species will affect the degree of

difficulty.

CENAM,

GLHK, HSA,

KRISS, LNE,

NIM, NIMT,

NMIJ

CENAM: Interference of 40Ar16O with

the measurement of 56Fe was removed

by using medium resolution mode.

KRISS: Interferences including Pd were

avoided using alternative choice of

isotope.

LNE (Cd): Matrix matching for matrix

blank subtraction.

LNE (Fe): Use of CCT to remove ArO

interference.

NIM: We choose 56Fe/57Fe, 68Zn/67Zn

and 111Cd/110Cd to do the IDMS

measurement and calculation. There is

no isobaric interference, but Fe affected

by oxide.

NIMT: For Fe analysis, used gas mode

to remove polyatomic interferences. For

Cd analysis, need to confirm with

another spiking isotope.

NMIJ: Interference of 40Ar16O with the

measurement of 56Fe was removed by

high-energy collision gas.

Detector deadtime correction

Measurement of, and correction for, ion detector

deadtime. Importance increases in situations

where high ion count rates are encountered.

GLHK, HSA,

KRISS, LNE,

NIM, NIMT,

NMIJ

NIM: The ICP-MS instrument does

dead time correction automatically.

Mass bias/fractionation control and

correction

Techniques used to determine, monitor, and

correct for mass bias/fractionation.

GLHK, HSA,

KRISS, LNE,

NIM, NIMT,

NMIJ

NIM: Mass bias is corrected by using

primary standard for Cd and isotope

CRMs for Zn and Fe. Considering the

variation of isotope abundance in

different samples and matrix effect, we

of 47


encountered

specially determined Zn, Cd and Fe

isotope abundance of the shrimp

sample.

Spike calibration

Techniques used to determine the analyte

concentration in the enriched isotopic spike

solution.

CENAM,

GLHK, KRISS,

LNE, NIM,

NIMT, NMIJ

CENAM (Fe, Zn, Cd): Not required for

“Exact matching IDMS”

“HSA (Fe): Not required for “Exact

Matching” IDMS

NIM: Primary standard solutions were

used to calibrate 57Fe and 67Zn spikes.

of 47

Inorganic Core Capabilities Table APMP Supplementary Comparison: APMP.QM-S5 Institutes: ANSTO, JSI, KRISS Method: INAA Analytes: As, Cd, Fe, Zn


encountered

Sample preparation

Procedures used to prepare samples for irradiation;

determination of the mass basis (e.g., determination of

dry mass basis); procedures to minimize sample loss

during preparation; procedures to minimize

contamination with the elements of interest (highest

difficulty for determination of low levels of elements that

are ubiquitous in the sample preparation environment).

ANSTO, JSI,

KRISS

JSI: Aliquots varied from 0.23 to

0.24 g. Samples were pelletized

using a manual hydraulic press

into pellets 10 mm in diameter

and 2.8 mm high. Each pellet was

sealed in polyethylene foil.

KRISS: Aliquots of about 0.16 g

of the sample were pelletized

using a manual hydraulic press in

diameter 13 mm and 2 mm thick.

Standards preparation

Procedures used to prepare element standards or other

comparators used for standardization. (e.g., low

difficulty for use of pure elements or compounds; higher

difficulty for procedures involving dissolution and

dilution, or dilution with solid matrices.)

All JSI: IRMM-530R Al-0.1%Au

alloy in form of foil with

thickness of 0.1 mm was used.

Discs of about 6 mm in diameter

were prepared. Each disc was

sealed in polyethylene foil.

KRISS: Arsenic standard solution

was transferred to cellulose filter

papers. They were air dried and

pelletized using a manual

hydraulic press in diameter 13

mm and 1.3 mm thick.

General applications

Procedures associated with specific method of NAA and

the evaluation of the associated uncertainties for

comparator NAA, ko NAA, or other method specific

parameters not described below.

ANSTO, JSI,

KRISS

JSI: A sample and standard

Al-0.1%Au were stacked

together, fixed in the polyethylene

vial in sandwich form and

irradiated in the TRIGA reactor.

Characterization of irradiation

channel in the carousel facility

(CF) of TRIGA reactor and

absolute calibration of the HPGe

detector are needed. Optimization

and validation of the k0-INAA

with different matrix certified

reference materials are necessary.

Concentration levels in the

sample for As, Fe and Zn have to

be suitable for INAA.

Determination of peak areas (complex

spectra/small peaks)

Procedures used to determine peak areas. (e.g., high

difficulty for small peak areas on complex backgrounds

or determination of areas for multiple unresolved peaks.)

ANSTO, JSI,

KRISS

JSI: For peak area evaluation, the

HyperLab 2002 program was

used. No difficulties in net peak

areas determination were

encountered for As-76 at 559.1

of 47


encountered

keV, Fe-59 at 1099.3 keV and

1291.6 keV, and for Zn-65 at

1115.5 keV. Expected peak of

Cd/In-115m at 336.2 keV was

below the background.

KRISS: Net count rate of the peak

of the primary gamma-ray energy

(559 keV) was small (~ 3 cps) but

not so bad for qualification.

Correction for spectral interferences

Procedures used to determine peak areas from

interfering nuclides and subtraction of the appropriate

number of counts from the peak of interest. Level of

difficulty increases with the number of corrections

needed and the magnitude of the corrections relative to

the total peak area.

All JSI: Negligible background

spectrum corrections were used in

this study (subtraction of recent

background spectrum for all

gamma spectra was applied). No

corrections for gamma-ray

interferences were applied for

radionuclides As-76, Fe-59 and

Zn-65.

KRISS: No gamma-ray peak from

the elements which might cause

spectral interference with 559

keV of As-76 was found.

Correction of fast neutron and fission

interferences

Procedures used to determine the contributions from fast

neutron reactions or fission of U to the peak area of

interest. The level of difficulty is related to the magnitude

of the corrections needed.

All JSI: Used irradiation channel in

the CF of the TRIGA reactor

(IC-40) has a

thermal-to-epithermal flux ratio

of 28.6 and a thermal-to-fast flux

ratio of 7.8. For the studied

radionuclides the threshold

reactions are negligible.

KRISS: The irradiation facility is

well thermalized.

Fission interference does not

cause any problem for As

analysis.

Corrections for sample and standard

geometry differences

Procedures used to determine correction factors for

differences in sample and standard irradiation and

counting geometries. These may include, e.g., use of flux

monitors to determine irradiation geometry correction

factors, and calculated correction factors based on

measured thicknesses and sample-to-detector distances.

Level of difficulty increases with the magnitude of the

correction.

All JSI: A standard Al-0.1%Au was

used as comparator and neutron

flux monitor. A sample and

standard Al-0.1%Au were stacked

together, fixed in the polyethylene

vial in sandwich form and

irradiated. Based on this

procedure, corrections for axial

neutron flux gradient inside the

polyethylene vial were applied.

Differences in sample/standard

geometry are taken into account

and they are calculated by the

Kayzero for Windows

(KayWin®) software.

Corrections or uncertainty assessments for

high count rates

All JSI: HPGe detector with 40 %

relative efficiency connected to

of 47


encountered

Procedures used to correct for losses in the analyzer due

to high count rates; e.g., set up and validation of

loss-free counting hardware, use of mathematical

corrections for pulse pileup as a function of analyzer

dead time, etc. Level of difficulty increases with the

magnitude of the correction.

MULTIPORT II multichannel

analyzer (Canberra) and

GENIE-2000 Spectroscopy

software were used.

Measurements were carried out at

such distances that the dead time

was kept below 5 % with

negligible random coincidences.

KRISS: Detector dead time was

less than 4 %.

Corrections for neutron absorption or

scattering differences between samples and

standards

Procedures used to correct for differences between

neutron exposure of samples and standards associated

with differences in the absorbing and scattering power;

e.g., corrections derived from measurements of different

amounts of materials or thicknesses of materials, or

calculations based on cross-section values to correct for

neutron attenuation. Level of difficulty increases with the

magnitude of the correction.

All JSI: The standard Al-0.1%Au

(nuclide Au-198 (T1/2=2.695 d)

at gamma line of 411.8 keV) was

used for axial neutron flux

gradient corrections in the

sample. Radial flux gradient is

negligible due to similar diameter

of sample and standard. Thermal

and epithermal self-shielding

factors are equal to 1.

KRISS: Major composition of the

sample is nearly the same as that

of cellulous filter paper (standard

comparator).

Corrections for differences in neutron

exposure of samples and standards

For some NAA applications, samples and standards are

irradiated individually and corrections are needed for

any differences in neutron exposures. Corrections may

be based on, e.g., results from flux monitors or estimates

based on knowledge of the facility.

All JSI: The samples and standards

were irradiated together.

KRISS: Neutron flux monitors

(Al-Au foil, IRMM-530R) were

used for the correction.

Corrections for gamma-ray attenuation

Procedures used to correct for differences in gamma-ray

attenuation between samples and standards; typically

relevant only for high-z sample or standard matrices and

where samples and standards differ. Level of difficulty

increases with the magnitude of the correction.

All JSI: Corrections for gamma-ray

attenuations in sample/standard

were calculated by Kayzero for

Windows (KayWin®) software

via effective solid angle

calculations (SOLCOI

subroutine). Different measuring

distances from the top of the

HPGe detector for sample and

standard can be used due to

absolute calibration of the HPGe

detector.

KRISS: Major composition of the

sample is nearly the same as that

of cellulous filter paper (standard

comparator).

of 47

Inorganic Core Capabilities Table APMP Supplementary Comparison: APMP.QM-S5 Institutes: INTI, NIS, NPLI Method: AAS (FAAS, GF-AAS or electrothermal AAS, HG-AAS) Analytes: INTI : Fe, Zn by FAAS; As, Cd by GF-AAS NPLI: Fe, Zn by FAAS; As by HG-AAS NIS: As, Cd by electrothermal AAS; Fe, Zn by FAAS


encountered


All techniques and procedures employed to reduce potential

contamination of samples as well as blank correction

procedures. The level of difficulty is greatest for analytes that are

environmentally ubiquitous and also present at very low


INTI, NIS, NPLI INTI (Cd): Low

concentration in the

sample.



primarily organic in nature into solution suitable for liquid

sample introduction to the ETA-AAS.

INTI, NIS, NPLI NIS: Dissolution should

be carried out carefully

and completely because

incomplete dissolution

may affect the element

conc.



primarily inorganic in nature into solution suitable for liquid

sample introduction to the ETA-AAS.

INTI, NIS



potentially volatile analyte elements during sample treatment and

storage.

INTI, NIS INTI: MW with closed

vessel.

NIS: It may be lost during

the dissolution process.

Pre-concentration

Techniques and procedures used to increase the concentration of

the analyte introduced to the ETA-AAS. Includes evaporation,

ion-exchange, extraction, precipitation procedures, but not vapor

generation procedures.

NIS

Matrix separation

Techniques and procedures used to isolate the analyte(s) from

the sample matrix to avoid or reduce interferences caused by the

matrix. Includes ion-exchange, extraction, precipitation


NIS NIS: Cadmium is affected

by the presence of arsenic

and iron. Std. addition

calibration is used.

Hydride preconcentration/matrix separation of

volatile species.

Coupling of a hydride system to the ETA-AAS and optimization

of conditions.

All


The preparation of calibration standards and the strategy for

instrument calibration. Includes external calibration and

standard additions procedures. Also use of matrix-matched

standards to minimize effect of interferences.

INTI, NIS, NPLI INTI (As): Standard

addition

Signal detection INTI, NIS INTI: Matrix modifier,

of 47

The detection and recording of the absorption signals of

analytes. The degree of difficulty increases for analytes present

at low concentrations, of low atomic absorption coefficient.

Requires selection of operating conditions such as light source,

absorption line, Zeeman background correction conditions.

Includes selection of signal processing conditions (peak area or

height).

Mg+Pd, Zeeman

Background Correction.

Peak Area

Memory effect

Any techniques used to avoid, remove or reduce the carry-over of

analyte between consecutively measured standards and/or

samples.

All

Optimization of the furnace temperature program

Optimization of temperature and duration of steps for sample

drying, pyrolysis to remove (residual) organics, and atomization.

Furnace temperature program to minimize analyte loss in the

drying/pyrolysis steps, while maximizing analyte vaporization in

the atomization step.

INTI, NIS INTI: STPF condition

(Stabilized Temperature

Platform Furnace).

Atomization Step with fast

ramp, hold time 5s and

stop gas flow. Matrix

modifier: Pd+Mg for both

element.

Correction or removal of matrix effects or

interferences

Chemical or instrumental procedures used to avoid or correct for

spectral and non-spectral interferences. Includes effects of

differences in viscosity and chemical equilibrium states of

analyte between the standard and sample. Selection of matrix

modifier to adjust volatility of analyte and/or matrix to eliminate

these effects is also included. Addition of reactive gases (e.g.

oxygen) to the carrier gas to improve matrix separation. Also

included is Zeeman or other background correction techniques to

remove interference due to absorption and scattering from

coexisting molecules/atoms in the sample.

INTI, NIS INTI: Zeeman

Background Correction

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