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Proficiency testing scheme report PTWFD - SCCPs Written the 10th May 2011

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PROFICIENCY TESTING SCHEME REPORT

PTWFD-SCCPs: Short chain chloroparaffins (C10-C13 Chloroalkanes) in surface waters

Report issued on the 10th of May 2011 .

Written by Ronan Charpentier Association A.G.L.A.E. 629, avenue de la République 59 000 Lille FRANCE

+33 (0) 3 20 16 91 40 +33 (0) 3 20 16 91 41

@ [email protected] www.association-aglae.fr

Cancel and replace the report issued on the 6th of May 2011, due to a mistake in the spiked concentration and the participants’ mean uncertainties.


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INTRODUCTION This proficiency testing was provided by A.G.L.A.E. as part of the PT-WFD (Proficiency Testing for the Water Framework Directive) network, in collaboration with the following proficiency testing providers:

BSG HU Hamburg Germany www.hamburg.de/ringversuche [email protected]

BIPEA, FRANCE www.bipea.org/en/index.htm [email protected]

Kemijski Institut Ljubljana Slovenija, Slovenia http://www.ki.si/en/ [email protected]

LGC Standards - Proficiency Testing, United Kingdom www.lgcpt.com [email protected]

QUALITYCONSULT srl, Italy /www.aqc.it/en/ [email protected]

Proftest SYKE, Finnish Environment Institute, Laboratories, Finland www.environment.fi/syke/proftest [email protected]

VITUKI Non-profit Ltd., HUNGARY www.vituki.hu/ [email protected]

For further information on PT-WFD, please see: http://www.pt-wfd.eu/index.shtml


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TABLE OF CONTENTS PRESENTATION OF THE PROFICIENCY TESTING........................................................4 MATERIAL PREPARATION ...........................................................................................4 DESIGN OF THE PROFICIENCY TESTING ....................................................................5 SENDING OF THE SAMPLES.........................................................................................6 QUALITY OF THE MATERIALS......................................................................................7 DATA PROCESSING AND ANALYTICAL PERFORMANCE EVALUATION.........................7 APPROACH OF THE TRUENESS ....................................................................................8 DEVIATIONS BETWEEN ANALYTICAL MODALITIES ..................................................12 COMMENTS AND CONCLUSION .................................................................................12 DESIGN AND IMPLEMENTATION OF THE PROFICIENCY TESTING............................15 ENCLOSED ANNEXES .................................................................................................15 ACKNOWLEDGMENTS................................................................................................15


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PRESENTATION OF THE PROFICIENCY TESTING Testing period: November 2010 – January 2011 Closing date: 12 January 2011 Type of matrix used: surface water diluted with tap water Number of batches: 3 Analysed items: C10-C13 chloroalkanes (SCCPs) Number of participants: 31. The following table displays the detail of these participants:

Registration via Number of participants

BIPEA 1

BSG 11

SYKE 1

LGC 1

PTWFD network 15

AGLAE 17

TOTAL 31

MATERIAL PREPARATION The subcontractor laboratory in charge of the sample preparation was:

IPL Santé, Environnement Durables Nord 1, rue du Professeur Calmette 59046 LILLE CEDEX FRANCE Supervisor: Mr Eric PIQUE


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The material preparation modalities are detailed in the following table:

Batch identification

Batch 1 (Bottles labeled A and B)

Batch 2 (Bottles labeled C and D)

Batch 3 (Bottles labeled E and F)

Parameters C10-C13 Chloroalkanes C10-C13 Chloroalkanes C10-C13 Chloroalkanes

Matrix Surface water (160L) + tap water (240L)

Treatment 2 mm sieving of the surface water and sodium thiosulfate dechlorination of the tap water Matrix

characterization Biochemical oxygen demand = 7.0 mg of O2.L-1 ; Total suspended materials = 4.0 mg.L-1

Stabilization None

Fractionation Continuous racking under mechanic stirring, bottle by bottle

Spiking Directly inside the bottles in

C10-C13 chloroalkanes : 51.5% chlorine content

Directly inside the bottles in C10-C13 chloroalkanes :

55.5% chlorine content

Directly inside the bottles in C10-C13 chloroalkanes : 63%

chlorine content Standard used for the spiking

D. Ehrenstorfer – Ref : X23105100CY



Packaging 1000 mL white glass bottles 1000 mL white glass bottles 1000 mL white glass bottles DESIGN OF THE PROFICIENCY TESTING Each participant received six bottles from 3 batches spiked at the same concentration level but with different chlorine contents. One analysis was carried out on each bottle (design with one replicate on two samples issued from the same batch).


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SENDING OF THE SAMPLES The testing materials were prepared on 16 November 2010 and sent on 23 November 2010. The following table shows the receipt dates of the parcels and the sample temperatures upon receipt (information given by the participants).

Laboratory code

Sample temperature at receipt (°C) Receipt date

1 7 24/11/10 2 6 24/11/10 3 5 25/11/10 4 7 24/11/10 5 5 24/11/10 6 7.3 24/11/10 7 5.2 24/11/10 9 2.9 24/11/10

11 7.5 24/11/10 12 5.9 24/11/10 14 10 24/11/10 16 3 24/11/10 17 4 29/11/10 18 4 25/11/10 20 - 26/11/10 21 5.5 08/12/10 22 7 26/11/10 23 6 26/11/10 24 5 26/11/10 25 3 26/11/10 26 4.5 26/11/10 27 4 26/11/10 28 8 26/11/10 29 - 26/11/10 30 8 26/11/10 31 4 26/11/10

Note: the laboratory 21’s parcel was sent on 7 December 2010 in consequence of a late subscription.


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QUALITY OF THE MATERIALS The quality of the materials was verified for all the analysed parameters. The materials stability was checked thanks to the study of the participants’ results distribution in function of the declared treatment starting dates. Additionally, a control was led on the second batch (bottles C and D) by the subcontractor laboratory, in order to complete the stability evaluation. The homogeneity of the batches was evaluated through the study of the participants’ results. Like for the stability study, a complementary monitoring was carried out by the subcontractor laboratory for the second batch. These verifications have shown that the batches were stable and homogeneous enough for the implementation of proficiency testing: indeed, more than 95% of the mean square of the laboratories results’ dispersion (mean results per batch) corresponds to the variance of the laboratory component of the bias (according to ISO 5725) ; while only less than 5% of the dispersion of one laboratory’s results to an other (in terms of mean square) is potentially attributable to a lack of stability or homogeneity of the batch. DATA PROCESSING AND ANALYTICAL PERFORMANCE EVALUATION The statistical evaluation of the data was performed according to the A and S algorithms described in the European standard ISO 13528 (05) « Statistical methods for use in proficiency testing by interlaboratory comparisons ». This data processing was carried out on all the participants’ results, besides the results such as « lower than the quantification limit ». The analytical performances of the participants were evaluated according to the criteria specified within the PT-WFD, namely:

- the assigned reference value to the item (m) is the mean of the results, calculated according to algorithm A from standard ISO 13528;

- the standard deviation for proficiency assessment is set in comparison to the assigned reference value: SDPA = 0.25·m.

z-scores are calculated according to: SDPA

mxz )( −=

In which: x= mean result of the laboratory m = assigned reference value to the item (algorithm A) SDPA = 0.25·m The evaluation of the results depends on the following criteria:

|z| ≤ 2.00 Satisfactory result 2.00 < |z| < 3.00 Questionable result |z| ≥ 3.00 Unsatisfactory result


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The following table and plot display the number and percentage of satisfactory, questionable and unsatisfactory results for each batch.

Batch 1 (chlorine content: 51.5%)

Batch 2 (chlorine content: 55.5%)

Batch 3 (chlorine content: 63%)

Number of |z| ≤ 2.00 16 (53%) 21 (70%) 20 (67%) Number of 2.00 < |z| < 3.00 8 (27%) 5 (17%) 3 (10%)

Number of |z| ≥ 3.00 6 (20%) 4 (13%) 7 (23%)

Z-scores distribution

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Batch 1 Batch 2 Batch 3

Number of |z| ≤ 2.0 Number of 2.00 < |z| < 3.00 Number of |z| ≥ 3.00

APPROACH OF THE TRUENESS The following table compares the spiked concentration value with the mean value observed by the participants, accounting for the confidence interval of both quantities. Note: the uncertainty on the spiked concentration value was calculated according to the standard ENV 13005 : 1999 (Guide To The Expression Of Uncertainty In Measurement) with a coverage factor k = 2. The expanded uncertainty on the value observed by the participants is equal to:

pS

U Zpt 25.1)1(%,95 ⋅±=−

in which:

- p is the number of laboratories who returned a result - t p )1(%,95 −

is the fractile of the Student’s t-distribution, with α=5% and p-1 freedom degrees

- Sz is the standard deviation resulting from the algorithm A.


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Item C10-C13 Chloroalkanes (batch 1 – chlorine content: 51.5%)

C10-C13 Chloroalkanes (batch 2 – chlorine content: 55.5%)

C10-C13 Chloroalkanes (batch 3 – chlorine

content: 63%)

Initial concentration in the matrix <0.4 <0.4 <0.4

Spiked concentration 4.937 4.937 4.937

Uncertainty of spiked concentration ± 0.277 ± 0.277 ± 0.277

Value observed by the participants 2.832 3.540 4.324

Uncertainty of the value observed by the participants

± 0.859 ± 0.824 ± 1.303

Recovery rate % (= m/spiked

concentration x 100) 57% 72% 88%

Spiked concentration value found? NO NO YES

Units in µg.L-1

The mean values observed by the participants are lower than the spiked concentrations values, more particularly for the batch 1, spiked with a 51.5% chlorine content C10-C13 chloroalkanes mix. As a result, several laboratories that have assessed results close to the spiked concentrations are showing unsatisfactory z-scores (see following table).


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C10-C13 chloroalkanes Batch 1 (51.5% chlorine

content)

C10-C13 chloroalkanes Batch 2 (55.5% chlorine

content)

C10-C13 chloroalkanes Batch 3 (63% chlorine content)

Laboratory code

Deviation from the spiked

concentration in % z-score


concentration in % z-score


concentration in %z-score

1 -27% +1.06 -26% +0.15 -14% -0.09 2 +16% +4.09 -4% +1.36 -9% +0.15 3 -58% -1.10 -29% -0.03 -41% -1.29 4 +1% +3.05 -29% -0.05 -46% -1.53 5 -39% +0.27 +7% +1.97 +176% +8.61 6 -26% +1.13 +17% +2.55 +28% +1.85 7 <+103% <+10.12 <+103% <+7.30 <+103% <+5.258 - - - - - - 9 -7% +2.47 +33% +3.41 +126% +6.32 10 -51% -0.61 -17% +0.63 +77% +4.09 11 -38% +0.33 -6% +1.22 +13% +1.14 12 -41% +0.10 -38% -0.56 -63% -2.32 13 +153% +13.65 +568% +33.29 +224% +10.8014 -79% -2.53 -73% -2.47 -53% -1.83 15 -69% -1.84 -47% -1.02 +9% +0.98 16 -60% -1.22 -39% -0.62 -46% -1.54 17 -27% +1.11 +12% +2.24 +5% +0.81 18 -96% -3.73 -72% -2.47 -52% -1.79 19 -74% -2.19 -56% -1.56 +3% +0.69 20 -40% +0.22 -44% -0.87 -42% -1.36 21 -91% -3.40 -92% -3.57 -90% -3.55 22 -14% +2.02 -30% -0.09 -84% -3.25 23 -21% +1.48 -24% +0.23 -24% -0.51 24 -25% +1.20 -40% -0.67 -40% -1.27 25 -6% +2.57 -2% +1.45 +20% +1.48 26 -58% -1.07 +3% +1.73 +46% +2.68 27 -1% +2.89 -20% +0.44 -22% -0.42 28 -91% -3.37 -87% -3.29 -92% -3.62 29 -73% -2.15 -47% -1.04 -5% +0.33 30 -82% -2.78 -71% -2.41 -64% -2.33 31 -65% -1.55 -30% -0.12 +17% +1.37

The deviations from the spiked concentrations higher than 50% and 75% are indicated with the following colours: >50% and >75%. In order to verify if there were any laboratories that have found the spiked concentration in the 3 batches, we calculated the sum of squared z-scores determined in relation to the spiked concentration (SSz).


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For each laboratory:

SSz = (zsc1)²+ (zsc2)²+ (zsc3)²

In which:

Zsc1 = SDPAscx )( 1 −

zsc2 = SDPAscx )( 2 −

zsc3 = SDPAscx )( 3 −

and: x1 : laboratory’s mean result for batch 1 x2 : laboratory’s mean result for batch 2 x3 : laboratory’s mean result for batch 3 sc: spiked concentration (identical for the 3 batches)

SDPA = 0.25·m The SSz are following a chi-square distribution with 3 freedom degrees and can be interpreted in the following way:

- if SSz ≤ 7.81 : satisfactory; - if 7.81< SSz ≤ 11.34 : questionable; - if SSz > 11.34 : unsatisfactory.

The higher SSz is, the further the laboratory’s results are from the spiked concentration. The laboratory with the smallest deviation in comparison to the spiked concentrations for the 3 batches is then the laboratory 2 (see following table).

Laboratory code SSz Laboratory code SSz

1 2.60 17 1.41 2 0.56 18 27.48 3 9.46 19 13.83 4 4.76 20 8.43 5 52.14 21 39.98 6 2.87 22 12.91 7 - 23 2.56 8 - 24 6.20 9 27.22 25 0.70

10 14.23 26 8.82 11 2.62 27 1.41 12 11.45 28 38.88 13 634.85 29 12.20 14 22.80 30 25.51 15 11.23 31 8.70 16 11.69


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DEVIATIONS BETWEEN ANALYTICAL MODALITIES The data processing was not disrupted by potential deviations due to the analytical modalities (there were no multiple populations of results). For each batch, we studied the laboratories’ results distribution depending on the used analytical modalities (see enclosed plots). This study did not show deviations between analytical modalities. Let us remind that we must be very cautious towards the interpretation of the discrepancies we might observe on these plots. Indeed: - on the one hand, these disparities would be sporadic observations, that could not be reasonably

generalised without confirmation; - on the other hand, interlaboratory proficiency testing are not expressly designed for analytical

modalities effect measurement. As a result, the comparison statistical tests are not always powerful enough, and there is a high risk of confusion between the studied factor and another unidentified hidden factor (and then a risk to lend the effect erroneously).

However, on this testing’s data, we can observe that: - on the batch 2 (spiked with a 55.5% chlorine content chloroalkanes mix), the results of the

laboratories using a calibration with 3 different chlorine contents are distinguished from the other laboratories’ results by a visibly lesser dispersion;

- the results obtained without purification appear more scattered than the ones acquired after purification.

COMMENTS AND CONCLUSION The dispersion of the participants’ results is quite high, with reproducibilities stated in variation coefficients, going from 49.5% to 64%. As a result, there was a very high number of unsatisfactory z-scores, considering the mode of calculation of the standard deviation for the proficiency evaluation, which is equal to 25% of the assigned value to the item. It appears that this dispersion is less important for the sample batch spiked with a 55.5% chlorine content in C10-C13 chloroalkanes mix. We can also note that this chlorine content was the most used during calibrations (see the chlorine contents’ distribution plot). To note as well that the uncertainty on the consensus value is high due to the important dispersion of the results. Finally, Mr Matthew Whetton, from LGC, pointed out that the deviation from the spiked concentration varied with the samples’ chlorine content. The general tendency being that the spiked concentration is best found when the chlorine content increases. However, it seems that the recovery rates’ evolution varies depending on the participants. Some laboratories show a recovery rate independent from the chlorine content, or even find a closer result from the spiked concentration when the chlorine content is lower. In order to clarify these observations we classified the laboratories depending on the deviations from the spiked concentrations they obtained on the 3 batches. We then have been able to identify 5 categories of laboratories.


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The first class includes two laboratories that observe particularly high values on the third batch. The second class comprises the laboratories with much lower values than the spiked concentrations, no matter the chlorine content. The third and fourth classes associate the laboratories that have a tendency to get closer from the spiked concentration as the chlorine content increases. The laboratories from the class n°3 detect on average higher values; and the one from the class n°4 find very close values from the spiked concentration for the third batch (63% chlorine content). Finally, the fifth class brings together the laboratories that have an almost constant deviation from the spiked concentration (deviation between 0% and -50%) on all of the three batches. Some of these laboratories show their apparent recovery decreasing on the third batch.

Evolution of the deviations from the spiked concentrations depending on the samples' chlorine content

-100%

-50%

0%

50%

100%

150%

200%

Dev

iati

on f

rom

th

e sp

iked

con

cen

trat

ion

(%

)

1

2

3

4

5

6

9

10

11

12

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

Batch 1 - 51.5% chlorine content

Batch 2 - 55.5% chlorine content

Batch 3 - 63% chlorine content

Laboratory code

Class n°1 Class n°2 Class n°3 Class n°4

Class n°5


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We then verified if this laboratories’ classification could be explained by the analytical modalities used by the participants (analytical line and number of standards). It seems that this is not the case. Indeed, each class brings together laboratories that employed different analytical modalities, as seen in the following table. Class

number Laboratory

code Batch 1 Batch 2 Batch 3 Analytical line Number of standards

1 5 -39% 7% 176% L/L extraction then GC/ECD analysis 1 1 9 -7% 33% 126% L/L extraction then GC/ECNI-MS analysis 1 2 14 -79% -73% -53% L/L extraction then GC/ECD analysis 1 2 18 -96% -72% -52% L/L extraction then GC/ECNI-MS analysis - 2 21 -91% -92% -90% S/L extraction then GC/MS analysis - 2 28 -91% -87% -92% L/L extraction then GC/ECNI-MS analysis 2 2 30 -82% -71% -64% L/L extraction then GC/ECNI-MS analysis 1 3 6 -26% 17% 28% L/L extraction then GC/ECD analysis 1 3 10 -51% -17% 77% L/L extraction then GC/ECD analysis 3 3 11 -38% -6% 13% L/L extraction then GC/MS/MS analysis 1 3 17 -27% 12% 5% L/L extraction then GC/MS/MS analysis 2 3 25 -6% -2% 20% L/L extraction then GC-MS (NCI) analysis 3 3 26 -58% 3% 46% L/L extraction then GC/ECNI-MS analysis 3 4 15 -69% -47% 9% L/L extraction then GC/ECNI-MS analysis 1 4 19 -74% -56% 3% - 1 4 29 -73% -47% -5% L/L extraction then GC/ECNI-MS analysis 3 4 31 -65% -30% 17% L/L extraction then GC/ECNI-MS analysis 3 5 1 -27% -26% -14% L/L extraction then GC/MS analysis 1 5 2 16% -4% -9% L/L extraction then GC/ECD analysis 3 5 3 -58% -29% -41% L/L extraction then GC/ECNI-MS analysis 3 5 4 1% -29% -46% L/L extraction then GC/IE-MS analysis 1 5 12 -41% -38% -63% L/L extraction then GC/ECD analysis 3 5 16 -60% -39% -46% L/L extraction then GC/ECD analysis 1 5 20 -40% -44% -42% S/L extraction then GC/MS analysis 3 5 22 -14% -30% -84% L/L extraction then GC/MS/MS analysis - 5 23 -21% -24% -24% L/L extraction then GC/ECNI-MS analysis 5 5 24 -25% -40% -40% L/L extraction then GC/ECNI-MS analysis 3 5 27 -1% -20% -22% L/L extraction then GC/ECNI-MS analysis 3

Lastly, we contacted Dr Sabine Geiß from Thüringer Landesanstalt für Umwelt und Geologie, convener of the ISO/TC147/SC2/WG59 working group, which is currently developing the new ISO/DIS 12010 standard “Water quality – Determination of short chain polychlorinated alkanes (SCCP) in water – Method using gas chromatography / mass spectrometry (GC/MS) and electron capture negative ionisation (ECNI)”. Dr Geiß pointed out that during the tests made for the standard development they also observed higher results when the chlorine contents were higher. However, the increase of the C10-C13 chloroalkanes contents depending on the samples’ chlorine content stayed negligible considering the measurement error.


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She also mentioned the very low recovery rate (about 50%) they obtained with the calibration standard Ehrenstorfer « SCCP C10 to C13, 51.5% Chlorine content », standard that we also used to spike our samples and for which the mean recovery rate observed during the testing is 57%. For the next proficiency testing, we will then consider to spike our samples with different standards. Finally, we are also envisaging to target lower concentration levels. DESIGN AND IMPLEMENTATION OF THE PROFICIENCY TESTING The following persons participated in the design and in the implementation of this proficiency test, under the supervision of Mr Delattre (President of the Association) and Mr Guarini (Director), in collaboration with Mr Hennequin (member of the Technical Committee and Honour Vice-President of the Association) and Mr Pointillard (President of the Technical Committee).

Technical design Statistical analysis

Confidentiality management

Supervision of Quality

Mrs Lacoste Miss Hoenner Mr Charpentier Mr Thieffry Mrs De Buchy

In case of a divergence between the French and English versions of this document, the French version shall prevail. ENCLOSED ANNEXES

Subject of the document Nature Number of pages

Reference and precision values 1 table 1 z-scores summary 1 table 1 Contents in C10-C13 Chloroalkanes observed by the participants on the batch 1 (51.5% chlorine content) 1 table + 1 plot 2

Contents in C10-C13 Chloroalkanes observed by the participants on the batch 2 (55.5% chlorine content) 1 table + 1 plot 2

Contents in C10-C13 Chloroalkanes observed by the participants on the batch 3 (63% chlorine content) 1 table + 1 plot 2

Distribution of the standards’ chlorine contents used by the participants 1 table 1

Results’ distribution plots (in function of the analytical modalities) Plots 9

ACKNOWLEDGMENTS We would like to thank our partners from the PT-WFD network for their useful comments. We are also grateful to Dr Sabine Geiß for her advice and observations.

ANNEXES

C10-C13 Chloroalkanes Batch 1 (51.5% chlorine content)

IC inf 1,974 Glossary :m 2,832 m : consensus value, resulting from the algorithm A

IC sup 3,691 ICinf : lower bound of the confidence interval of m (with 5% risk)r = 0,52 ICsup : upper bound of the confidence interval of m (with 5% risk)

Observed R = 5,13 r : repeatability limit precision CVr% = 6,5 R : reproducibility limit

CVR% = 64,0 CVr% : repetability stated in variation coefficient (Sr/m)*100R / r = 10,0 CVR% : reproducibility stated in variation coefficient (SR/m)*100

SDPA = 0,708 R/r : repeatability on reproductibily ratiosz = 1,806 SDPA : standard deviation for proficiency assesment (z-scores calculation) (0.25*m)unit : µg.L-1 sz : standard deviation of the laboratories'results, resulting from algorithm A

C10-C13 Chloroalkanes Batch 2 (55.5% chlorine content)

IC inf 2,716m 3,540

IC sup 4,364r = 0,83

Observed R = 4,94precision CVr% = 8,0

CVR% = 49,5R / r = 6,0

SDPA = 0,885sz = 1,733unit : µg.L-1

C10-C13 Chloroalkanes Batch 3 (63 % chlorine content)

IC inf 3,021m 4,324

IC sup 5,627r = 0,84

Observed R = 7,78precision CVr% = 7,0

CVR% = 63,5R / r = 9,5

SDPA = 1,081sz = 2,741unit : µg.L-1

Reference and precision values

Consensus value

Consensus value

Consensus value

A.G.L.A.E. - PTWFD - SCCPs - November 2010 / January 2011

Laboratory CodeC10-C13 chloroalkanes

Batch 1 (51.5% chlorine content)C10-C13 Chloroalkanes

Batch 2 (55.5% chlorine content)C10-C13 Chloroalkanes

Batch 3 (63% chlorine content)Laboratory Code

1 +1,06 +0,15 -0,09 12 +4,09 +1,36 +0,15 23 -1,10 -0,03 -1,29 34 +3,05 -0,05 -1,53 45 +0,27 +1,97 +8,61 56 +1,13 +2,55 +1,85 67 <+10.12 <+7.30 <+5.25 78 - - - 89 +2,47 +3,41 +6,32 910 -0,61 +0,63 +4,09 1011 +0,33 +1,22 +1,14 1112 +0,10 -0,56 -2,32 1213 +13,65 +33,29 +10,80 1314 -2,53 -2,47 -1,83 1415 -1,84 -1,02 +0,98 1516 -1,22 -0,62 -1,54 1617 +1,11 +2,24 +0,81 1718 -3,73 -2,47 -1,79 1819 -2,19 -1,56 +0,69 1920 +0,22 -0,87 -1,36 2021 -3,40 -3,57 -3,55 2122 +2,02 -0,09 -3,25 2223 +1,48 +0,23 -0,51 2324 +1,20 -0,67 -1,27 2425 +2,57 +1,45 +1,48 2526 -1,07 +1,73 +2,68 2627 +2,89 +0,44 -0,42 2728 -3,37 -3,29 -3,62 2829 -2,15 -1,04 +0,33 2930 -2,78 -2,41 -2,33 3031 -1,55 -0,12 +1,37 31

z-scores summary

A.G.L.A.E. - PTWFD - SCCPs - November 2010 / January 2011

RESULTS

Assigned value (mean) = 2.832Standard Deviation for Proficiency Assessment (0,25*m) = 0.708Spiked concentration = 4.937

(unit in µg.L -1 )

Bottle A Bottle B

Laboratory Code Replicate 1 Replicate 1 Mean z-score

1 3.82 3.34 3.580 +1.062 5.37 6.08 5.725 +4.093 2 01 2 09 2 050 -1 103 2.01 2.09 2.050 -1.104 4.97 5.01 4.990 +3.055 3.03 3.02 3.025 +0.276 3.81 3.45 3.630 +1.137 < 10.00 < 10.00 <10.000 <+10.128 - - - -9 4.72 4.44 4.580 +2.4710 2.30 2.50 2.400 -0.6111 2 92 3 21 3 065 +0 3311 2.92 3.21 3.065 +0.3312 2.90 2.91 2.905 +0.1013 14.00 11.00 12.500 +13.6514 1.09 0.99 1.040 -2.5315 1.46 1.60 1.530 -1.8416 1.88 2.05 1.965 -1.2217 3.55 3.69 3.620 +1.1118 0.19 0.19 0.190 -3.7319 1 26 1 31 1 285 2 1919 1.26 1.31 1.285 -2.1920 3.00 2.97 2.985 +0.2221 0.61 0.23 0.423 -3.4022 4.30 4.23 4.265 +2.0223 3.90 3.86 3.880 +1.4824 3.61 3.76 3.685 +1.2025 4.79 4.52 4.655 +2.5726 2.02 2.13 2.075 -1.0727 5 36 4 39 4 875 2 8927 5.36 4.39 4.875 +2.8928 0.46 0.43 0.445 -3.3729 1.58 1.04 1.310 -2.1530 0.80 0.93 0.865 -2.7831 1.73 1.74 1.735 -1.55

Short chain chloroparaffins - SCCPsShort chain chloroparaffins - SCCPs(C10-C13 chloroalkanes) in surface water

Parameter C10-C13 chloroalkanes (51.5% chlorine content)

Unit µg.L-1

A.G.L.A.E. - PTWFD - SCCPs - November 2010 - January 2011 Table 1/1

1531

16 3 2610

12 20 5 11

1 17 6 2423

229 25

27 4

2

m

ICinf

ICsup

z = +3.00

z = +2.00

2,00

3,00

4,00

5,00

6,00

Cont

ent

in µ

g.L‐

1

C10‐C13 chloroalkanes ‐ Batch 1 (51.5% chlorine content)

A.G.L.A.E. ‐ PTWFD ‐ SCCPs ‐ November 2010 / January 2011

1821 28

3014

19 2915

3116 3 26

10

12 20 5 11

1 17 6 2423

229 25

27 4

2

m

ICinf

ICsup

z = +3.00

z = +2.00

z = ‐2.00

z = ‐3.00

0,00

1,00

2,00

3,00

4,00

5,00

6,00

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1

Cont

ent

in µ

g.L‐

1

Accrued number of laboratories


Laboratories' results Assigned reference value to the item Spiked concentration

RESULTS


(unit in µg.L -1 )

Bottle C Bottle D


1 3.79 3.55 3.670 +0.152 4.69 4.80 4.745 +1.363 3 47 3 56 3 515 -0 033 3.47 3.56 3.515 -0.034 3.49 3.50 3.495 -0.055 5.06 5.51 5.285 +1.976 5.48 6.12 5.800 +2.557 < 10.00 < 10.00 <10.000 <+7.308 - - - -9 6.89 6.22 6.555 +3.4110 4.80 3.40 4.100 +0.6311 4 96 4 28 4 620 +1 2211 4.96 4.28 4.620 +1.2212 2.52 3.56 3.040 -0.5613 31.00 35.00 33.000 +33.2914 1.47 1.24 1.355 -2.4715 2.61 2.66 2.635 -1.0216 3.26 2.72 2.990 -0.6217 5.68 5.37 5.525 +2.2418 1.32 1.40 1.358 -2.4719 2 25 2 07 2 160 1 5619 2.25 2.07 2.160 -1.5620 2.90 2.64 2.770 -0.8721 0.31 0.45 0.381 -3.5722 3.62 3.30 3.460 -0.0923 3.70 3.78 3.740 +0.2324 2.99 2.91 2.950 -0.6725 4.77 4.87 4.822 +1.4526 4.79 5.35 5.070 +1.7327 3 99 3 87 3 930 0 4427 3.99 3.87 3.930 +0.4428 0.65 0.61 0.630 -3.2929 2.76 2.48 2.620 -1.0430 1.39 1.43 1.410 -2.4131 3.47 3.40 3.435 -0.12


Parameter C10-C13 chloroalkanes (55.5% chlorine content)

Unit µg.L-1


19

29 15 2024 16 12

31 22 4 3 1 2327

10

11 2 2526

517

6

9

m

IC inf

IC sup

z= +3,00

z= +2,00

2 00

3,00

4,00

5,00

6,00

7,00Co

nten

t in

µg.

L‐1



2128

14 18 30

19

29 15 2024 16 12

31 22 4 3 1 2327

10

11 2 2526

517

6

9

m

IC inf

IC sup

z= +3,00

z= +2,00

z= ‐2,00

z= ‐3,00

0,00

1,00

2,00

3,00

4,00

5,00

6,00

7,00

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1

Cont

ent

in µ

g.L‐

1




RESULTS


(unit in µg.L -1 )

Bottle E Bottle F


1 3.94 4.51 4.225 -0.092 4.55 4.43 4.490 +0.153 2 87 2 98 2 925 -1 293 2.87 2.98 2.925 -1.294 2.52 2.81 2.665 -1.535 13.46 13.81 13.635 +8.616 6.74 5.90 6.320 +1.857 < 10.00 < 10.00 <10.000 <+5.258 - - - -9 10.56 11.76 11.160 +6.3210 9.00 8.50 8.750 +4.0911 5 60 5 52 5 560 +1 1411 5.60 5.52 5.560 +1.1412 1.68 1.96 1.820 -2.3213 19.00 13.00 16.000 +10.8014 2.47 2.22 2.345 -1.8315 5.35 5.42 5.385 +0.9816 2.75 2.57 2.660 -1.5417 4.95 5.46 5.205 +0.8118 2.37 2.40 2.384 -1.7919 5 18 4 95 5 065 +0 6919 5.18 4.95 5.065 +0.6920 2.55 3.16 2.855 -1.3621 0.40 0.59 0.491 -3.5522 0.83 0.79 0.810 -3.2523 3.83 3.72 3.775 -0.5124 2.92 2.99 2.955 -1.2725 5.94 5.91 5.925 +1.4826 7.65 6.80 7.225 +2.6827 3 73 4 02 3 875 0 4227 3.73 4.02 3.875 -0.4228 0.42 0.40 0.410 -3.6229 3.47 5.90 4.685 +0.3330 1.74 1.86 1.800 -2.3331 5.90 5.70 5.800 +1.37


Parameter C10-C13 chloroalkanes (63% chlorine content)

Unit µg.L-1


16 4 20 3 24

23 271

2 2919 17 15 11 31 25

6

26

10

9

m

IC i f

IC sup

z= +3.00

z= +2.00

4,00

6,00

8,00

10,00

12,00Co

nten

t in

µg.

L‐1

C10‐C13 chloroalkanes ‐ Batch 3 (63% chlorine content)


28 2122

30 1214 18

16 4 20 3 24

23 271

2 2919 17 15 11 31 25

6

26

10

9

m

IC inf

IC sup

z= +3.00

z= +2.00

z = ‐2.00

z = ‐3.000,00

2,00

4,00

6,00

8,00

10,00

12,00

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1

Cont

ent

in µ

g.L‐

1


C10‐C13 chloroalkanes ‐ Batch 3 (63% chlorine content)


Standard's chlorine contentLaboratory code 49.00% 49.90% 51.50% 55.00% 55.50% 56.00% 57.25% 61.00% 63.00% 67.00% 66.70% 69.00%

1 - - - - YES - - - - - - -2 - - YES - YES - - - YES - - -3 - - YES - YES - - - YES - - -4 - - YES - - - - - - - - -5 - - - - YES - - - - - - -6 - - - - YES - - - - - - -7 - - - - YES - - - - - - -8 - - - - - - - - - - - -9 - - YES - - - - - - - - -10 - - YES - YES - - - YES - - -11 - - - YES - - - - - - - -12 - - YES - YES - - - YES - - -13 - - YES - YES - - - YES - - -14 - - - - - - - - YES - - -15 - - - - YES - - - - - - -16 - - YES - - - - - - - - -17 - - YES - - - - - YES - - -18 - - - - - - - - YES - - -19 - - - - YES - - - - - - -20 - - YES - YES - - - YES - - -21 - - - - - - - - - - - -22 - - - - YES - - - - - - -23 - - YES - YES - YES YES YES - - -24 - - YES - YES - - - YES - - -25 - - YES - YES - - - YES - - -26 YES - - - - YES - - - - YES -27 - - YES - YES - - - YES - - -28 - - YES - - YES - - - - - -29 YES - - - - YES - - - - YES -30 - - - - - - - - YES - - -31 YES - - - - YES - - - - YES -

Total : 3 0 15 1 17 4 1 1 14 0 3 0

Distribution of the chlorine contents of the standards used by the participants


0

2

4

6

8

10

12

14

1 2 3 4 5

Num

ber

of la

bora

tori

es

Number of standards with a different chlorine content ?

0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6

C10‐

C13c

hlor

oalk

anes

con

tent

(µg

.L‐1

)

Number of standard with different chlorine contents

Batch 1 (51.5% chlorine content)

Laboratory mean

Spiked concentration

0

2

4

6

8

10

12

14

1 2 3 4 5

Num

ber

of la

bora

tori

es


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6

C10‐

C13c

hlor

oalk

anes

con

tent

(µg

.L‐1

)



Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6C10‐

C13

chlo

roal

kane

s co

nten

t (µ

g.L‐

1 )



Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6

C10‐

C13

chlo

roal

kane

s (µ

g.L‐

1 )

Batch 3 (63% chlorine content)

Mean laboratory


0

2

4

6

8

10

12

14

1 2 3 4 5

Num

ber

of la

bora

tori

es


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6

C10‐

C13c

hlor

oalk

anes

con

tent

(µg

.L‐1

)



Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6C10‐

C13

chlo

roal

kane

s co

nten

t (µ

g.L‐

1 )



Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6

C10‐

C13

chlo

roal

kane

s (µ

g.L‐

1 )



Mean laboratory


A.G.L.A.E. ‐ PTWFD ‐ SCCPs ‐ November 2010 / january 2011

Caption :Calibration type1/ one standard : 51.5%2/ one standard : 55.5%3/ one standard : 55%4/ one standard : 63%5/ two standards : 51.5% and 63%6/ two standards : 51.5% and 56%7/ three standards : 51.5%, 55.5% and 63%8/ three standards : 49%, 56% and 66.7%9/ others

0123456789

One standard :

51.5%

One standard :

55.5%

One standard :

55%

One standard :

63%

Two standards : 51.5% and

63%


56%

Three standards :

51.5%, 55.5% and

63%

Three standards : 49%, 56% and 66.7%

Others

Num

ber o

f lab

orat

orie

sCalibration type adopted

0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10

C10‐

C13

chlo

roal

kane

s co

nten

t (µ

g.L‐

1 )

Calibration type


Laboratory mean


0123456789

One standard :

51.5%

One standard :

55.5%

One standard :

55%

One standard :

63%


63%


56%

Three standards :

51.5%, 55.5% and

63%


Others

Num

ber o

f lab

orat

orie


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10

C10‐

C13

chlo

roal

kane

s co

nten

t (µ

g.L‐

1 )

Calibration type


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10

C10‐

C13

chlo

roal

kane

s co

nten

t (µ

g.L‐

1 )

Calibration type


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10

C10‐

C13

chl

oroa

lkan

es c

onte

nt (µ

g.L‐

1 )


Laboratory mean


0123456789

One standard :

51.5%

One standard :

55.5%

One standard :

55%

One standard :

63%


63%


56%

Three standards :

51.5%, 55.5% and

63%


Others

Num

ber o

f lab

orat

orie


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10

C10‐

C13

chlo

roal

kane

s co

nten

t (µ

g.L‐

1 )

Calibration type


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10

C10‐

C13

chlo

roal

kane

s co

nten

t (µ

g.L‐

1 )

Calibration type


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10

C10‐

C13

chl

oroa

lkan

es c

onte

nt (µ

g.L‐

1 )

Calibration type


Laboratory mean



Caption :Utilization of an internal standard ?1/ yes

2/ no

0

2

4

6

8

10

12

14

16

18

20

yes no

Num

ber o

f lab

orat

orie

sUtilization of an internal standard ?

0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

utilization of an internal standard ?


Laboratory mean


0

2

4

6

8

10

12

14

16

18

20

yes no

Num

ber o

f lab

orat

orie


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)



Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)



Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)


Laboratory mean


0

2

4

6

8

10

12

14

16

18

20

yes no

Num

ber o

f lab

orat

orie


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)



Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)



Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)



Laboratory mean



Caption :Analytical line adopted1/ L/L extraction then GC/ECD analysis2/ L/L extraction then GC/MS analysis3/ L/L extraction then GC/MS/MS analysis4/ L/L extraction then GC/EI‐MS analysis5/ L/L extraction then GC/EI‐MS/MS analysis6/ L/L extraction then GC/ECNI‐MS analysis7/ S/L extraction then GC/ECD analysis8/ S/L extraction then GC/MS analysis

s) 9/ S/L extraction then GC/MS/MS analysis10/ S/L extraction then GC/EI‐MS analysis11/ S/L extraction then GC/EI‐MS/MS analysis12/ S/L extraction then GC/ECNI‐MS analysis13/ other : L/L extraction then GC/MS (NCI) analysis

0

2

4

6

8

10

12

14

L/L extraction then GC/ECD

analysis

L/L extraction then GC/MS

analysis

L/L extraction then GC/MS/MS

analysis

L/L extraction then GC/EI‐MS

analysis

L/L extraction then GC/ECNI‐

MS analysis

S/L extraction then GC/MS

analysis

Other : L/L extraction then

GC/MS (NCI) analysis

Num

ber

of la

bora

tori

es

Analytical line

0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

C10‐

C13

chlo

roal

kane

s co

nten

t (µ

g.L‐

1 )

Analytical line


Laboratory mean



0

2

4

6

8

10

12

14

L/L extraction then GC/ECD

analysis

L/L extraction then GC/MS

analysis

L/L extraction then GC/MS/MS

analysis

L/L extraction then GC/EI‐MS

analysis

L/L extraction then GC/ECNI‐

MS analysis

S/L extraction then GC/MS

analysis

Other : L/L extraction then

GC/MS (NCI) analysis

Num

ber

of la

bora

tori

es

Analytical line

0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

C10‐

C13

chlo

roal

kane

s co

nten

t (µ

g.L‐

1 )

Analytical line


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

C10‐

C13

chlo

roal

kane

s co

nten

t (µ

g.L‐

1 )

Analytical line


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

C10‐

C13

chlo

roal

kane

s co

nten

t (µ

g.L‐

1 )

Analytical line


Laboratory mean



Caption :Extraction modalities1/ directly in the bottle

2/ with rinsing of the bottle3/ without rinsing of the bottle

0

2

4

6

8

10

12

14

directly in the bottle with rinsing of the bottle without rinsing of the bottle

Num

ber o

f lab

orat

orie

s

Extraction type ?

0

2

4

6

8

10

12

14

16

18

0 1 2 3 4

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Extraction type


Laboratory mean


0

2

4

6

8

10

12

14


Num

ber o

f lab

orat

orie

s

Extraction type ?

0

2

4

6

8

10

12

14

16

18

0 1 2 3 4

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Extraction type


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Extraction type


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4neur

en

chlo

roal

cane

s C1

0‐C1

3 (e

n µg

.L‐1

)


Laboratory mean


0

2

4

6

8

10

12

14


Num

ber o

f lab

orat

orie

s

Extraction type ?

0

2

4

6

8

10

12

14

16

18

0 1 2 3 4

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Extraction type


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Extraction type


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4Tene

ur e

n ch

loro

alca

nes

C10‐

C13

(en

µg.L

‐1)

Extraction type


Laboratory mean



Caption :Extraction solvent1/ n‐hexane2/ cyclohexane3/ n‐heptane4/ dichloromethane5/ dichloromethane / ethyl acetate6/ pentane7/ hexane/dichloromethane8/ Isohexane/ Diethyl ether9/ n‐hexane/dichloromethane

0

2

4

6

8

10

12

Num

ber o

f lab

orat

orie

sExtraction solvent used

0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Extraction solvent


Laboratory mean


0

2

4

6

8

10

12

Num

ber o

f lab

orat

orie


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Extraction solvent


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Extraction solvent


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)


Laboratory mean


0

2

4

6

8

10

12

Num

ber o

f lab

orat

orie


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Extraction solvent


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Extraction solvent


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3 4 5 6 7 8 9 10

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Extraction solvent


Laboratory mean



Caption :Purification phase ?1/ yes2/ no

0

5

10

15

20

25

yes no

Num

ber o

f lab

orat

orie

sPurification phase ?

0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Purification phase


Laboratory mean


0

5

10

15

20

25

yes no

Num

ber o

f lab

orat

orie


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Purification phase


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Purification phase


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)


Laboratory mean


0

5

10

15

20

25

yes no

Num

ber o

f lab

orat

orie


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Purification phase


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Purification phase


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Purification phase


Laboratory mean



Caption :Concentration phase1/ yes2/ no

0

5

10

15

20

25

30

yes no

Num

ber o

f lab

orat

orie

sConcentration phase ?

0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Concentration phase


Laboratory mean


0

5

10

15

20

25

30

yes no

Num

ber o

f lab

orat

orie


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Concentration phase


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Concentration phase


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)


Laboratory mean


0

5

10

15

20

25

30

yes no

Num

ber o

f lab

orat

orie


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Concentration phase


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Concentration phase


Laboratory mean


0

2

4

6

8

10

12

14

16

18

0 1 2 3

C10‐

C13

chlo

roal

kane

s co

nten

t (µg

.L‐1

)

Concentration phase


Laboratory mean



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