Blad 1 van 78
Liquefied Natural Gas
Correlation Scheme
Evaluation Report Round 23
Report number S-CH.09.09
© Copyright VSL B.V.
Page 2 of 78
VSL
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E [email protected]
I www.vsl.nl
This work has been carried out by
A. Baldan
Project leader
Y. Quist
Coordinator
P.R. Ziel
In the period
January to April 2009
On request of
VSL B.V. Department of Calibration
& Reference Materials
Confidentiality statement
In this report, the participants are identified by means of a laboratory code, which is assigned by VSL. The assigned
code is kept confidential.
Signature
Approved by
Y. Quist
A. Baldan
Project coordinator
Project manager
Date
Date
© Copyright VSL B.V.
All rights reserved. No part of this publication may be reproduced or transmitted in any form or by
any means, electronic or mechanical, including photocopy, recording, or any other information
storage and retrieval system, without prior permission from VSL B.V.
Page 3 of 78
Table of contents
Table of contents
3
1
Introduction
4
2
Homogeneity testing and determination of batch reference values
5
2.1 Test procedure
5
2.2 Results
5
Results of the participants
7
3.1 Reported results
7
3.2 Consensus values
7
3.3 Evaluation of the results
9
3
3.3.1
Introduction
9
3.3.2
LNG composition
10
3.3.3
Propane composition
10
3.3.4
MR composition
11
3.3.5
Sulphur components in methane
11
3.3.6
Coefficients of variation for evaluation
11
3.4 List of participants
12
4
Discussion and conclusions
13
5
References
14
6
List of symbols
15
Annex A: Statistical procedure for homogeneity testing
16
A1
Statistics
17
A2
References
18
Annex B: Results of homogeneity study
19
B1
Results for the LNG composition
20
B2
Results for the propane composition
30
B3
Results for the MR composition
37
B4
Results for sulphur components in methane
41
Annex C: Procedure for statistical analysis and evaluation of laboratory results
47
C1
Determination of consensus values
48
C2
Qualification of the laboratory results
49
C3
References
50
Annex D: Laboratory results and evaluation
51
D1
Results for the LNG composition
52
D2
Results for propane composition
62
D3
Results for MR composition
69
D4
Results for sulphur components in methane
73
Page 4 of 78
1
Introduction
Started in January 2003, a proficiency testing scheme is organized to evaluate the performance of the
participating laboratories in measuring the composition of four types of gas mixtures: Liquefied Natural Gas (LNG)
composition, Propane composition, Main Refrigerant (MR) composition, and sulphur components in methane.
The composition of the gas mixtures is shown in table 1.1.
Table 1.1: Composition of the gas mixtures, expressed in amount-of-substance fractions
LNG composition
(% mol/mol)
Propane composition
(% mol/mol)
MR composition
(% mol/mol)
Ethane
3–9
Ethane
0.25 – 3
Ethane
20 – 35
Propane
2–5
i-Butane
0.03 – 0.7
Propane
5 – 15
i-Butane
0.1 – 1
n-Butane
0.03 – 0.7
Nitrogen
8 – 16
n-Butane
0.1 – 1
i-Pentane
0.02 – 0.08
Methane
balance gas
i-Pentane
0.02 – 0.5
n-Pentane
0.02 – 0.08
n-Pentane
0.02 – 0.5
Nitrogen
0.1 – 2
Hexane
0.01 – 0.1
Propane
balance gas
Nitrogen
0.1 – 8
Carbon dioxide
0.1 – 8
Helium
Methane
0.0 – 0.1
balance gas
Sulphur components in
methane
(10-6 mol/mol)
Hydrogen
10 – 40
sulphide
Dimethyl
sulphide
10 – 40
Ethyl mercaptane
10 – 40
Methyl
mercaptane
10 – 40
Carbonyl
sulphide
10 – 40
Total sulphur
50 – 200
Scott Specialty Gases NL carried out the preparation of the gas mixtures and organized the transport of the gas
cylinders to the participants. VSL carries out the homogeneity testing, establishes the reference values, and is
responsible for data treatment and reporting.
rd
The 23 round was carried out in the period of January to April 2009.
The results of the laboratories have been evaluated by means of Z-scores using fixed criteria.
Page 5 of 78
2
Homogeneity testing and determination of batch
reference values
2.1 Test procedure
A batch of 14 cylinders were prepared containing LNG composition, a batch of 14 cylinders containing Propane
composition, a batch of 13 containing MR composition and a batch of 16 cylinders containing sulphur
components in methane. From each batch, 4 cylinders were selected and subjected to a homogeneity
assessment.
The objective of this assessment is to determine the “between-bottle” homogeneity standard deviation (sbb) and to
compare this value with the expected scattering of laboratory averages in the interlaboratory comparison. This sbb
should be negligible when compared with the (expected) between laboratory standard deviation. The statistical
procedure applied is described in annex A.
For the analysis of LNG composition, propane composition and MR composition a two channel HP 6890 gas
chromatograph equipped with both TCD and TCD/FID in series is used.
For the analysis of LNG composition, gas mixture is introduced on a Porapak R column where nitrogen, carbon
dioxide and the hydrocarbons are separated using temperature programming and helium as carrier. For the
detection of the components eluting from the column either the TCD (N2, CO2) or the FID (hydrocarbons) is used.
For the analysis of propane composition and MR composition the same measurement procedure is applied.
For the calibration of the system (performed in the same run as the analysis of the gas samples with unknown
composition) a minimum of 8 Primary Standard gas Mixtures (PSMs) containing synthetic gases are used. The
composition of the PSMs is traceable to SI-units. The detector response is corrected for variations in the
atmospheric pressure. Using the composition data of the PSMs and the corrected detector response (gravimetric
concentrations vs. peak area’s) calibration curves are set up for each component and used to determine the
concentration in the unknown sample(s).
For the determination of the sulphur components in methane a GC-AED is used. A minimum of 5 PSMs are used
for calibration.
The calculations for all of the calibrations are carried out according to ISO 6143 [1].
The average results for the four cylinders were used as the batch reference values. The uncertainty associated
with the batch reference values includes the contribution of the uncertainty in the measurement results as well as
the contribution due to inhomogeneity (see also annex A).
2.2 Results
All experimental results of the homogeneity test are presented in annex B. For each mixture, a summary of the
results is presented in tables 2.1 to 2.4. In these tables sr denotes the repeatability standard deviation of the
measurement and sR the reproducibility standard deviation. All values are relative standard deviations.
Although the between bottle inhomogeneity in most cases can be quantified at a certain analytical level, for the
purpose of the proficiency test the between bottle standard deviation can be neglected, since it is considerably
smaller than the between laboratory standard deviation (see chapter 3). The homogeneity of the batch may
therefore be regarded as sufficient for the purpose.
The calculated batch reference values (yref) and their expanded uncertainties for each mixture are also listed in
tables 2.1 to 2.4.
Page 6 of 78
Table 2.1: Summary statistics homogeneity test for LNG composition (relative values) and reference
values in %mol/mol
Parameter
Methane
Ethane
Propane
i-Butane
n-Butane
i-Pentane
n-Pentane
n-Hexane
Carbon dioxide
Nitrogen
yref
83.70
8.040
3.294
0.7986
0.8979
0.3021
0.2017
0.04982
0.7078
2.011
Uref (k=2)
0.29
0.040
0.016
0.0050
0.0060
0.0024
0.0016
0.00051
0.0051
0.010
sr
0.020%
0.017%
0.015%
0.015%
0.016%
0.014%
0.017%
0.018%
0.08%
0.09%
sbb
0.05%
0.038%
0.037%
0.034%
0.036%
0.038%
0.04%
0.07%
0.06%
0.07%
sR
0.06%
0.04%
0.04%
0.037%
0.039%
0.04%
0.04%
0.07%
0.10%
0.11%
Table 2.2: Summary statistics homogeneity test for propane composition (relative values) and reference
values in %mol/mol
Parameter
yref
Uref (k=2)
sr
sbb
sR
Ethane
2.510
0.023
0.019%
0.10%
0.10%
Propane
96.96
0.53
0.018%
0.11%
0.11%
i-Butane
0.3008
0.0030
0.022%
0.10%
0.10%
n-Butane
0.03038
0.00030
0.10%
0.10%
0.14%
i-Pentane
0.07550
0.00072
0.020%
0.10%
0.11%
n-Pentane
0.02277
0.00022
0.05%
0.11%
0.12%
Nitrogen
0.1022
0.0011
1.0%
0.26%
1.0%
Table 2.3: Summary statistics homogeneity test for MR composition (relative
values) and reference values in %mol/mol
Parameter
yref
Uref (k=2)
sr
sbb
sR
Methane
Ethane
Propane
Nitrogen
56.96
25.02
9.992
8.030
0.28
0.12
0.051
0.057
0.014%
0.013%
0.014%
0.22%
0.035%
0.033%
0.036%
0.12%
0.038%
0.036%
0.038%
0.25%
Table 2.4: Summary statistics homogeneity test for sulphur components in
methane (relative values) and reference values in µmol/mol
Parameter
yref
Uref (k=2)
sr
sbb
sR
Hydrogen sulphide
Dimethyl sulphide
Methyl mercaptane
Ethyl mercaptane
Carbonyl sulphide
Total sulphur
35.60
14.92
17.15
27.80
15.04
110.50
1.26
0.49
0.53
0.89
0.72
2.58
0.5%
0.8%
0.7%
0.7%
0.7%
0.6%
1.1%
0.8%
0.8%
0.7%
1.9%
0.6%
1.2%
1.2%
1.0%
1.0%
2.0%
0.8%
Page 7 of 78
3
Results of the participants
3.1 Reported results
15 laboratories participated in this round. The results of the laboratories were directly sent to VSL for data
treatment.
Not all laboratories participated for all mixtures and not all participants sent in results for all mixtures received. An
overview is presented in table 3.1.
Table 3.1: Participation and reported results
Lab #
LNG composition
Participation
Results
X
X
1
Propane composition
Participation
√
Results
X
MR composition
Participation
Results
X
X
√
X
√
Sulphur components
Participation
√
Results
X
√
X
3
√
√
X
√
√
√
X
√
X
√
√
4
X
X
X
X
X
X
√
√
5
X
√
X
√
X
√
X
√
X
√
√
X
6
X
√
√
X
7
√
√
√
√
√
√
√
√
8
√
√
√
√
√
√
√
X
9
√
X
√
X
√
X
√
X
10
√
√
X
X
X
X
X
X
11
√
X
12
√
√
X
√
X
√
X
√
X
√
X
√
X
√
13
√
√
√
X
√
X
√
X
X
√
√
√
X
X
X
X
X
X
2
14
X
X
15
X
X
X
√
1
Laboratory no. 3 did not report results for dimethyl sulphide, ethyl mercaptane and total sulphur in methane
2
Laboratory no. 4 did not report results for dimethyl sulphide and total sulphur in methane
1
2
The laboratories were requested to report their estimated measurement uncertainty. This would enable the
comparison of the results with the reference values. That is, the expanded measurement uncertainty (U) of a nonbiased result overlaps with the reference value and its uncertainty. Also it would enable to evaluate the results by
means of En-scores.
Participants no. 2, 6, 10, 13, 14 and 15 did not report measurement uncertainties.
3.2 Consensus values
The procedure for determination of the consensus values is described in annex C and the results are shown in
annex D.
In a number of cases outliers were detected (see annex C for the procedure applied). This is the case for the
results of laboratory 10 for i- and n-butane and i-pentane in LNG composition. The outliers were removed for
calculation of the final consensus values. The consensus values after outlier removal are listed in tables 3.2 to
3.5. In these tables m denotes the average, p the number of participants, sr the repeatability standard deviation sL
the between-laboratory standard deviation and sR the reproducibility standard deviation, yref the reference value
and Uref the expanded uncertainty of the reference value (k=2).
There should be no significant difference between the consensus and reference value. This is the case when the
calculated difference between these two is smaller than or equal to the expanded uncertainty, or:
m
y ref
U k
2
where U is the expanded uncertainty of the difference. The standard uncertainty of the difference, u , can be
calculated from the standard uncertainty of the consensus value, um, and the standard uncertainty of the
reference value, uref, according to:
(1)
Page 8 of 78
u2
2
uref
2
um
(2)
The uncertainty of the consensus value is calculated by dividing the reproducibility standard deviation by the
square root of the number of participants. Equation 2 therefore becomes:
u2
2
uref
2
(3)
p
sR
The expanded uncertainty of the difference is obtained by multiplying the standard uncertainty by a factor of 2.
The calculated differences between the consensus values and the reference values as well as their uncertainties
are presented in tables 3.2 to 3.5. As can be seen in these tables, the differences are in most cases smaller than
the expanded uncertainties. It can therefore be concluded that the consensus values in those cases do not differ
significantly from the reference values. Exceptions are the results for n-hexane in LNG composition and methyl
mercaptane in methane. The reasons for these differences are not known. There is, however, no reason to doubt
the reference values.
An overview of the relative between-laboratory standard deviations is shown in figure 3.1. The smallest between
laboratory standard deviations were obtained for the analysis of LNG composition (on average approx. 1.7%
relative), followed by the analysis of the propane composition (on average approx. 6.6% relative). A much higher
relative between-laboratory standard deviation is obtained for the analysis of sulphur components in methane and
for MR composition: 25 and 44%, respectively. The high between laboratory standard deviations for MR
composition were caused by the results of laboratory no. 2, who’s results are far off the reference values and
outside of the ranges mentioned in table 1.1. If the results of laboratory no. 2 were removed from the dataset
(they are not considered to be outliers), the average between laboratory standard deviation for MR composition
becomes approximately 0.9% relative.
Table 3.2: Summary of the consensus values for LNG composition after outlier removal and the
difference between the consensus value and the reference value, in %mol/mol
Parameter
Methane
Ethane
Propane
i-Butane
n-Butane
i-Pentane
n-Pentane
n-Hexane
Carbon dioxide
Nitrogen
m
p
sr
sL
83.77
8.03
3.288
0.798
0.896
0.305
0.200
0.0526
0.702
1.999
7
7
7
6
6
6
7
7
7
7
0.017
0.009
0.004
0.004
0.004
0.0026
0.0023
0.0004
0.0025
0.005
0.16
0.09
0.023
0.010
0.011
0.0039
0.006
0.0032
0.008
0.016
sR
U (k=2)
0.16
0.09
0.024
0.010
0.012
0.005
0.006
0.0032
0.008
0.017
0.08
-0.01
-0.006
0.000
-0.002
0.0025
-0.0013
0.0028
-0.006
-0.012
0.32
0.08
0.024
0.010
0.012
0.0045
0.0050
0.0025
0.008
0.016
Table 3.3: Summary of the consensus values for propane composition after outlier removal and the
difference between the consensus value and the reference value, in %mol/mol
Parameter
m
p
sr
Ethane
Propane
i-Butane
n-Butane
i-Pentane
n-Pentane
Nitrogen
2.52
96.94
0.303
0.0310
0.080
0.0216
0.107
5
5
5
4
5
4
4
0.13
0.09
0.0005
0.00021
0.00012
0.000088
0.0029
sL
sR
0.09
0.13
0.007
0.0011
0.010
0.0014
0.018
U (k=2)
0.16
0.16
0.007
0.0011
0.010
0.0014
0.019
0.01
-0.02
0.0023
0.0006
0.005
-0.0012
0.005
0.14
0.54
0.0066
0.0011
0.009
0.0014
0.019
Table 3.4: Summary of the consensus values for MR composition after outlier removal and the
difference between the consensus value and the reference value, in %mol/mol
Parameter
Methane
Ethane
Propane
Nitrogen
m
47
29
14
9.6
p
sr
6
6
6
6
0.06
0.027
0.024
0.029
sL
sR
22
9
9
3.5
U (k=2)
22
9
9
3.5
-10
4.3
3.9
1.5
18
7.6
7.2
2.8
Page 9 of 78
Table 3.5: Summary of the consensus value for sulphur components in methane after outlier removal
and the difference between the consensus value and the reference value, in µmol/mol
Parameter
Hydrogen sulphide
Dimethyl sulphide
Methyl mercaptane
Ethyl mercaptane
Carbonyl sulphide
Total sulphur
m
40
18
20.0
34
16.7
134
p
4
2
4
3
4
2
sr
0.5
0.33
0.22
0.34
0.24
2.3
sL
12
5
2.9
7
3.1
46
sR
12
5
2.9
7
3.1
46
46%
U (k=2)
5
2.7
2.9
6
1.7
23
12
7.8
2.9
8
3.2
66
63%
40%
Sulphur in methane
35%
sL (relative)
30%
MR composition
25%
Propane composition
20%
15%
10%
LNG composition
5%
0%
Figure 3.1: Relative between-laboratory standard deviations
3.3 Evaluation of the results
3.3.1 Introduction
The results of the laboratories have been evaluated with fixed limits derived from the reproducibilities mentioned
in ISO 6974-3 [2], for LNG composition, and the results of rounds 1 to 4, for the other mixtures as described in the
summary report of rounds 1 to 4 [3]. The values for the standard deviation for evaluation are listed in table 3.13.
Furthermore, also the En-values have been calculated. These values are given for information only. The
procedure for calculating the Z-scores and En-values is described in annex C.
The results have been presented in annex D. In the annex for each component in each mixture the following is
shown:
A table with for each laboratory the average results and standard deviation, the reported expanded
measurement uncertainty (U, k=2), the number of measurement results reported (n), the calculated raw Zscore (Zraw), an indication in case |Zraw| > 2, the calculated Z-score and the calculated En-value.
A table with the consensus values calculated from the laboratory results before outlier removal, including m,
sr, sL, sR, p, the median, MAD and AAD.
A table with the consensus values after outlier removal (|Zraw| > 2).
The reference value and its expanded uncertainty (Uref, k=2)
Page 10 of 78
A figure containing for each laboratory the average result with the reported U indicated by the error bars, and
the reference value and U indicated by means of, respectively, a solid line and dotted lines.
A figure containing for each laboratory the Z-scores.
3.3.2 LNG composition
As can be seen in annex D1, in most cases the laboratory results are close to the reference values and often
within the range of the uncertainty of the reference value.
Furthermore, it can be seen in annex D1 that the results of laboratory 10 show in for most parameters a bias. As
can be seen from table 3.6, this is also expressed by the relatively large Z-scores, the absolute values of which in
these cases exceed the value of 2.
Table 3.6: Z-scores for LNG composition
Lab Methane Ethane Propane i-Butane n-Butane i-Pentane n-Pentane n-Hexane Carbon Nitrogen
dioxide
3
6
7
8
10
12
13
0.13
-1.70
0.78
1.99
3.27
0.42
0.29
-0.17
1.47
-0.29
-1.45
-0.24
-0.10
-0.18
-0.18
-0.23
-0.25
-0.96
0.79
-0.26
-0.03
-0.05
0.65
-0.83
-0.03
-5.33
-0.46
0.02
0.35
0.61
-0.45
-0.59
-4.94
-0.49
0.06
-0.44
0.90
-0.26
0.84
-3.66
-0.16
-0.01
0.88
0.06
0.16
0.86
-2.49
-0.53
0.06
0.67
0.08
-0.04
3.09
2.36
0.01
0.54
0.07
0.01
-0.24
-0.19
-1.23
-0.07
-0.37
0.04
-0.51
-0.13
-0.19
-1.74
0.23
-0.19
Table 3.7: En-values for LNG composition
Lab Methane Ethane Propane i-Butane n-Butane i-Pentane n-Pentane n-Hexane Carbon Nitrogen
dioxide
3
7
8
12
0.03
0.16
0.47
0.11
-0.22
-0.16
-2.64
-0.11
-0.06
-0.22
-1.20
-0.24
-0.04
-1.52
-0.06
-0.94
0.22
-0.74
-1.11
-1.48
-0.23
-0.23
1.57
-0.20
0.47
0.14
1.18
-1.00
0.40
-0.02
1.25
0.01
0.15
-0.43
-0.05
-0.14
0.05
-0.07
-0.11
0.25
3.3.3 Propane composition
In annex D2 it can be seen that in most cases the results are in concordance with the reference values.
All labs, apart from laboratory no. 7, however report a deviating for at least one component, resulting in Z-scores,
the absolute values of which in these cases exceed the value of 2.
Laboratory no. 15 appeared to have relatively high reporting/detection limits: the laboratory reported for n-butane
three values: < 0.1, <0.1 and 0.2% mol/mol, and for n-pentane and nitrogen three a value of <0.1 %mol/mol. For
n-butane and n-pentane the reference values (0.03038 and 0.02277 %mol/mol, respectively) are indeed smaller
than 0.1 % mol/mol, for nitrogen, which has a reference value of 0.1022 % mol/mol, this is not the case.
Furthermore, the results reported by this lab for i-pentane (0.1 %mol/mol) are strongly deviation from the
reference value of 0.07550 %mol/mol.
Table 3.8: Z-scores for propane composition
Lab Ethane Propane i-Butane n-Butane i-Pentane n-Pentane Nitrogen
6
7
8
12
15
3.11
0.01
-0.69
0.12
-2.85
-1.86
-0.03
0.45
-0.61
1.80
1.23
0.23
-0.66
1.17
-0.10
-0.50
0.16
2.26
1.47
1.99
0.08
-0.79
-0.40
10.82
-4.06
0.18
-1.32
-0.11
-0.07
0.03
-1.10
14.51
Page 11 of 78
Table 3.9: En-values for propane composition
Lab Ethane Propane i-Butane n-Butane i-Pentane n-Pentane Nitrogen
7
8
12
0.00
-1.35
0.18
0.00
0.08
-0.11
0.07
-0.41
1.98
0.04
0.11
0.20
0.06
-0.51
-0.78
0.05
-0.25
-0.07
0.00
-0.74
4.75
3.3.4 MR composition
As can be seen in annex D3, in most cases the laboratory results agree well with the reference values. As can be
seen from table 3.10, this is also expressed by the relatively small Z-scores; the absolute values of which are in
these cases smaller than 2. The results of laboratory no. 2, however, are strongly deviating from the reference
values, which is expressed by the very high Z-scores.
Table 3.10: Z-scores MR composition
Lab Methane Ethane Propane Nitrogen
-86
85
133
65
2
6
0.63
-0.14
-0.87
-1.63
7
-0.05
-0.07
0.25
0.07
8
-0.67
1.37
0.38
-0.15
12
-0.23
0.57
-0.28
0.24
14
-0.38
-1.09
-0.96
0.17
Table 3.11: En-values MR composition
Lab Methane Ethane Propane Nitrogen
7
-0.02
-0.03
0.08
0.03
8
-0.77
0.76
0.39
-0.25
12
-0.27
0.38
-0.39
0.19
3.3.5 Sulphur components in methane
As can be seen from annex D4, relatively large differences between the results of the laboratories were obtained.
Laboratory no. 12 reported strongly deviating results for all components and laboratory no. 4 for the mercaptanes.
This is also expressed in Z-scores that are, in absolute sense, in all cases larger than 3.
Table 3.12: Z-scores sulphur components in methane
Lab
Hydrogen
sulphide
3
4
7
12
0.00
0.81
0.50
27.50
Dimethyl
sulphide
Methyl
mercaptane
Ethyl
mercaptane
Carbonyl
sulphide
-0.95
16.39
1.85
9.40
-1.71
7.04
7.93
-2.50
17.12
3.68
1.79
-0.61
17.18
Ethyl
mercaptane
Carbonyl
sulphide
6.55
-0.83
6.89
0.90
1.02
-0.13
2.49
Table 3.13: En-values sulphur components in methane
Lab
Hydrogen
Dimethyl
Methyl
sulphide
sulphide
mercaptane
3
4
7
12
0.00
0.66
0.20
9.75
-0.35
3.15
0.51
7.70
-0.59
1.26
Total sulphur
-0.56
11.29
Total sulphur
-0.61
5.14
3.3.6 Coefficients of variation for evaluation
In table 3.14 the values for the coefficient of variation and the reproducibility standard deviation are listed.
As can be seen in the table, for LNG composition the values of the coefficient of variation and the reproducibility
standard deviation are in most cases at the same level. For n-hexane in LNG composition and for most of the
components in the other mixtures, however, the variation between the results of the laboratories is relatively high
in comparison to the value of the coefficient of variation.
Page 12 of 78
Table 3.14: Values for coefficient of variation and sR
LNG composition
CVev
Propane composition
sR
CVev
MR composition
sR
CVev
sR
Ethane
1.1% 1.2% Ethane
2.0%
6.2% Ethane
1.0%
32%
Propane
1.1% 0.7% i-Butane
2.5%
2.2% Propane
1.5%
63%
i-Butane
2.2% 1.3% n-Butane
2.5%
3.5% Nitrogen
1.5%
36%
n-Butane
2.2% 1.3% i-Pentane
3.0%
13% Methane
1.0%
46%
i-Pentane
2.2% 1.5% n-Pentane
3.0%
6.4%
n-Pentane
2.2% 3.1% Nitrogen
3.0%
17%
n-Hexane
0.9% 6.0% Propane
0.1%
0.16%
Nitrogen
1.1% 1.2%
Carbon
dioxide
Methane
1.1% 0.8%
0.1% 0.19%
3.4 List of participants
The list of participants is removed from this report.
Sulphur components in
methane
CVev
sR
Hydrogen
sulphide
3.0%
31%
Dimethyl
sulphide
3.0%
31%
Methyl
3.0%
mercaptane
14%
Ethyl
3.0%
mercaptane
21%
Carbonyl
sulphide
Total
sulphur
3.0%
19%
5.0%
35%
Page 13 of 78
4
Discussion and conclusions
Not all of the participants reported a value for the measurement uncertainty. Since the publication of ISO/IEC
17025 [4] in 1999, both calibration and testing laboratories are required to estimate and express their
measurement uncertainty. This requirement is very important to both the laboratory and its customer.
Furthermore, it would enable the assessment of a laboratory result in view of its stated uncertainty through an Enscore. Many comparisons in the calibration area are operated in such a way.
For future rounds, each laboratory is encouraged to make the calculations for expanded uncertainty according to
the relevant documents [5, 6 and 7].
The homogeneity study indicated no significant contribution due to between-bottle variation. The evaluation
method for the homogeneity test allows including the results from the homogeneity test directly in the calculation
of the combined standard uncertainty of the batch of mixtures. In all cases, the combined standard uncertainty
from the determination of the composition and that of the homogeneity test was considerably lower than the
between laboratory standard deviation.
There is in general a good agreement between the reference values and the consensus values, as obtained from
the laboratory results, after removal of outliers. This implies that on average, the reference value is found by the
group of participants as well.
In general the individual laboratories performed well; the Z-scores are in most cases below the value of 2.
However, the determination of the amount-of-substance of sulphur components in methane seems to be
problematic for a number of laboratories. Also, for one laboratory the analysis of MR composition seems to have
been problematic.
Page 14 of 78
5
References
[1]
International Organization for Standardization, “ISO 6143:2001 Gas analysis - Comparison methods for
determining and checking the composition of calibration gas mixtures”
[2]
International Organization for Standardization, “ISO 6974-3:2000 Natural gas – Determination of
composition with defined uncertainty by gas chromatography – Part 3: Determination of hydrogen, helium,
oxygen, nitrogen, carbon dioxide and hydrocarbons up to C8 using two packed columns”
[3]
M. van Son and A.M.H. van der Veen, “Shell Gas Correlation Scheme Evaluation Rounds 1-4”, NMi VSL
Report S-MC-04.14, 25 June 2004
[4]
International Organization for Standardization, “ISO/IEC 17025:1999 General requirements for the
competence of testing and calibration laboratories”
[5]
European Co-operation for Accreditation, EA-4/02, 1999, Expression of the Uncertainty of Measurement in
Calibration”
[6]
EURACHEM/CITAC Guide, Quantifying uncertainty in analytical measurement, 2
[7]
BIPM, IEC, IFCC, ISO, IUPAC, IUPAP, OIML (1993) “Guide to the expression of uncertainty in
measurement”, first edition, ISO Geneva, 1993; also called “GUM”
nd
edition, 2000
Page 15 of 78
6
List of symbols
AAD
average of absolute deviations
CVev
coefficient of variation for evaluation
En
performance characteristic including the stated uncertainty
i
laboratory index
m
consensus value
MAD
median of absolute deviations
MSwithin
mean square within the groups (from ANOVA)
MSbetween
mean square between groups (from ANOVA)
ni
number of reported results by laboratory i
p
number of laboratories
sbb
between-bottle standard deviation (from homogeneity assessment)
sr
repeatability standard deviation
sL
between-laboratory standard deviation
sR
reproducibility standard deviation
SS
sum of squares
um
standard uncertainty of the consensus value
uref
standard uncertainty of the reference value
Uref
expanded uncertainty of the reference value
Ustat,i
expanded uncertainty stated by laboratory i
U
expanded uncertainty of the difference between the consensus and reference value
u
standard uncertainty of the difference between the consensus and reference value
yi
result of laboratory i
yref
reference value
Z
performance characteristic
ˆ
standard deviation for evaluation
difference between the consensus and reference value
Page 16 of 78
Annex A: Statistical procedure for homogeneity
testing
Annex A: Statistical procedure for homogeneity testing
Page 17 of 78
A1
Statistics
For evaluation of the results for homogeneity, unifactorial analysis of variance (“one-way ANOVA”) is applied. The
evaluation is carried out on the basis of the measured signals. The general background has been described
elsewhere [A1, A2]
On a matrix consisting of a cylinders times n observations, analysis of variance is applied. Each cylinder
represents a group. The first step leads to estimates for sums of squares that are calculated as follows.
The total sum of squares within the groups is calculated according to:
a ni
SSwithin
Yij
Yi
2
(A1)
i 1j 1
where Yi is the group average. Yij is the result for cylinder i, response j.
The total sum of squares between the groups is calculated according to:
2
a
SSamong
ni Y i
Y
(A2)
i 1
where
ni
a
1
Y
(A3)
Yij
a
ni
i 1j 1
i 1
The next step is the calculation of the means of squares (MS). The means of squares are calculated by dividing
the total sums of squares by the number of degrees of freedom.
The mean of squares within the groups is equal to the repeatability standard deviation, or:
SSwithin
MS within
s r2
a
ni
(A4)
a
i 1
The mean of squares between the groups is calculated according to:
SSamong
MSamong
(A5)
a 1
The between cylinder standard deviation may be calculated from MSamong and the repeatability standard deviation
according to:
2
sbb
sr2
MSamong
(A6)
n0
where
a
n0
1
a
a 1
i 1
ni
ni2
i 1
a
(A7)
ni
i 1
Furthermore the reproducibility standard deviation may be calculated according to:
2
sR
2
sbb
sr2
(A8)
Finally, the standard uncertainty contribution as a result of the batch inhomogeneity is calculated. The standard
uncertainty is calculated according to:
u
sbb
X
Y
where X is the average mole fraction for all cylinders analysed in the homogeneity test.
(A9)
Annex A: Statistical procedure for homogeneity testing
Page 18 of 78
A2
References
[A1]
Van der Veen A.M.H., Pauwels J., “Uncertainty calculations in the certification of reference materials. 1.
Principles of analysis of variance”, Accreditation and Quality Assurance 5 (2000), pp. 464-469
[A2]
Van der Veen A.M.H., Linsinger T.P.J, Pauwels J., “Uncertainty calculations in the certification of
reference materials. 2. Homogeneity study”, Accreditation and Quality Assurance 6 (2001), pp. 26-30
Page 19 of 78
Annex B: Results of homogeneity study
Annex B: Results of homogeneity study
Page 20 of 78
Results for the LNG composition
Nitrogen
(counts)
sample ID value #1
5600256 1204.1
5601908 1204.0
5601869 1199.3
5600157 1200.6
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
value #2 value #3
1202.7
1201.1
1201.3
1200.8
1201.9
1201.4
1201.7
1201.4
1201.6
1.1
0.8
1.4
4
1201.6
0.7
0.7
value #4
1203.8
1202.5
1200.3
1201.2
value #5
1202.2
1201.0
1199.8
1201.4
mean
1202.8
1201.9
1200.5
1201.3
0.09%
0.07%
0.11%
0.06%
0.06%
1220
1215
1210
1200
1195
1190
1185
5600157
5601869
1180
5601908
Mean value
1205
5600256
B1
s
1.2
1.3
1.1
0.4
n
5
5
5
5
Annex B: Results of homogeneity study
Page 21 of 78
Carbon dioxide
(counts)
sample ID value #1
5600256 489.5
5601908 489.6
5601869 487.9
5600157 488.4
value #2 value #3
489.0
488.6
488.8
488.6
488.7
488.6
488.8
489.0
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
488.8
0.4
0.27
0.5
4
488.79
0.23
0.23
value #4
489.6
489.2
488.4
488.8
value #5
489.1
488.0
488.3
488.6
mean
489.2
488.8
488.4
488.7
0.08%
0.06%
0.10%
0.05%
0.05%
496
494
492
488
486
484
482
5600157
5601869
5601908
480
5600256
Mean value
490
s
0.4
0.6
0.3
0.2
n
5
5
5
5
Annex B: Results of homogeneity study
Page 22 of 78
Methane
(counts)
sample ID
5600256
5601908
5601869
5600157
value #1
1628737
1628308
1628663
1630279
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
1629241
328
854
915
4
1629028
549
613
value #2 value #3
1628291 1628378
1628684 1629053
1629060 1629243
1630238 1630458
value #4
1628723
1629249
1629085
1630587
value #5
1628076
1629424
1629515
1630781
mean
1628441
1628944
1629113
1630468
0.020%
0.05%
0.06%
0.034%
0.038%
1636000
1634000
1632000
1628000
1626000
1624000
1622000
5600157
5601869
5601908
1620000
5600256
Mean value
1630000
s
286
450
310
224
n
5
5
5
5
Annex B: Results of homogeneity study
Page 23 of 78
Ethane
(counts)
sample ID
5600256
5601908
5601869
5600157
value #1
288127
288054
288104
288334
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
288192
48
109
119
4
288161
66
80
value #2 value #3
288076
288095
288142
288174
288153
288186
288311
288342
value #4
288137
288202
288154
288360
value #5
288035
288213
288227
288412
mean
288094
288157
288165
288352
0.017%
0.038%
0.04%
0.023%
0.028%
289000
288800
288600
288400
288000
287800
287600
287400
287200
5600157
5601869
5601908
287000
5600256
Mean value
288200
s
41
64
46
38
n
5
5
5
5
Annex B: Results of homogeneity study
Page 24 of 78
Propane
(counts)
sample ID
5600256
5601908
5601869
5600157
value #1
177345
177350
177338
177481
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
177394
26
65.8
71
4
177382
41
46
value #2 value #3
177315
177317
177358
177395
177379
177386
177468
177487
value #4
177369
177408
177374
177502
value #5
177288
177403
177423
177495
mean
177327
177383
177380
177486
0.015%
0.037%
0.040%
0.023%
0.026%
178000
177800
177400
177200
177000
5600157
5601869
5601908
176800
5600256
Mean value
177600
s
31
27
30
13
n
5
5
5
5
Annex B: Results of homogeneity study
Page 25 of 78
i-Butane
(counts)
sample ID value #1
5600256 57139
5601908 57139
5601869 57139
5600157 57177
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
value #2 value #3
57129
57127
57147
57156
57145
57150
57175
57176
57153
8
19
21
4
57150
13
13
value #4
57148
57162
57144
57184
value #5
57124
57162
57159
57188
mean
57133
57153
57147
57180
0.015%
0.034%
0.037%
0.023%
0.023%
57300
57250
57150
57100
57050
5600157
5601869
5601908
57000
5600256
Mean value
57200
s
10
10
8
6
n
5
5
5
5
Annex B: Results of homogeneity study
Page 26 of 78
n-Butane
(counts)
sample ID value #1
5600256 65711
5601908 65716
5601869 65720
5600157 65757
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
value #2 value #3
65697
65692
65722
65732
65721
65730
65757
65756
65730
10
23
26
4
65728
16
16
value #4
65724
65742
65717
65764
value #5
65691
65744
65733
65769
mean
65703
65731
65724
65761
0.016%
0.036%
0.039%
0.025%
0.025%
65900
65850
65800
65700
65650
65600
65550
5600157
5601869
5601908
65500
5600256
Mean value
65750
s
14
12
7
6
n
5
5
5
5
Annex B: Results of homogeneity study
Page 27 of 78
i-Pentane
(counts)
sample ID
5600256
5601908
5601869
5600157
value #1
27266.2
27272.8
27266.9
27285.6
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
value #2 value #3
27261.4
27263.8
27277.0
27282.3
27267.2
27269.4
27285.4
27287.2
27275
3.8
10
11
4
27274
9
9
value #4
27270.6
27283.5
27266.8
27287.1
value #5
27259.6
27284.4
27272.8
27291.9
mean
27264.3
27280.0
27268.6
27287.5
0.014%
0.038%
0.04%
0.032%
0.032%
27340
27320
27300
Mean value
27280
27260
27240
27220
5600157
5601869
5601908
5600256
27200
s
4.3
5.0
2.6
2.6
n
5
5
5
5
Annex B: Results of homogeneity study
Page 28 of 78
n-Pentane (counts)
sample ID
5600256
5601908
5601869
5600157
value #1
18832.9
18835.6
18830.3
18844.2
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
value #2 value #3
18828.4
18829.0
18839.8
18842.4
18830.0
18833.5
18844.6
18845.9
18838
3.2
8
8
4
18837
6
6
value #4
18833.8
18844.0
18832.2
18847.2
value #5
18825.6
18846.6
18836.3
18850.5
mean
18829.9
18841.7
18832.5
18846.5
0.017%
0.04%
0.04%
0.034%
0.034%
18950
18900
18800
18750
5600157
5601869
5601908
18700
5600256
Mean value
18850
s n
3.4 5
4.2 5
2.6 5
2.5 5
Annex B: Results of homogeneity study
Page 29 of 78
n-Hexane
(counts)
sample ID value #1
5600256 5605.2
5601908 5610.0
5601869 5603.5
5600157 5611.5
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
value #2 value #3
5604.8
5605.3
5611.6
5612.5
5604.3
5605.5
5611.8
5611.9
5609
1.0
4
4
4
5608.7
3.5
3.5
value #4
5606.9
5612.7
5605.5
5613.1
value #5
5604.7
5613.1
5606.3
5613.4
mean
5605.4
5612.0
5605.0
5612.3
0.018%
0.07%
0.07%
0.06%
0.06%
5650
5640
5630
5620
5600
5590
5580
5570
5560
5600157
5601869
5601908
5550
5600256
Mean value
5610
s
0.9
1.2
1.1
0.9
n
5
5
5
5
Annex B: Results of homogeneity study
Page 30 of 78
Results for the propane composition
Nitrogen
(counts)
sample ID value #1
5200663
63.0
5200709
5200711
64.5
5200739
64.2
value #2 value #3
62.9
62.9
64.1
63.4
63.0
62.9
63.1
62.9
Statistics (raw)
m
63.1
sr
0.6
s bb
0.16
sR
0.7
p
4
Median
63.13
MAD
0.24
AAD
0.23
value #4
62.7
63.2
62.2
62.9
value #5
61.8
63.3
62.9
62.7
mean
62.7
63.5
63.1
63.2
1.0%
0.26%
1.0%
0.38%
0.36%
68
67
66
65
63
62
61
60
59
5200739
5200711
58
5200663
Mean value
64
5200709
B2
s
0.5
0.4
0.9
0.6
n
5
4
5
5
Annex B: Results of homogeneity study
Page 31 of 78
Ethane
(counts)
sample ID value #1
5200663 92061
5200709 92250
5200711 92103
5200739 92077
Statistics (raw)
m
92135
sr
17
s bb
92
sR
93
p
4
Median
92099
MAD
57
AAD
68
value #2 value #3
92076
92064
92232
92285
92095
92122
92075
92081
value #4
92076
92295
92124
92081
value #5
92087
92290
92127
92101
mean
92073
92271
92114
92083
0.019%
0.10%
0.10%
0.06%
0.07%
93000
92800
92600
92400
92000
91800
91600
91400
91200
520073
9
520071
1
520070
9
91000
520066
3
Mean value
92200
s
10
28
14
11
n
5
5
5
5
Annex B: Results of homogeneity study
Page 32 of 78
Propane
(counts)
sample ID
5200663
5200709
5200711
5200739
value #1
5791037
5803997
5792198
5790914
Statistics (raw)
m
5795379
sr
1019
s bb
6390
sR
6471
p
4
Median
5792538
MAD
3784
AAD
4761
value #2 value #3
5792464 5790760
5802845 5805908
5792675 5794603
5790843 5791683
value #4
5791921
5805835
5794197
5791449
value #5
5792071
5805918
5793455
5792806
mean
s
n
5791650 721 5
5804901 1411 5
5793426 1007 5
5791539 792 5
0.018%
0.11%
0.11%
0.07%
0.08%
5880000
5860000
5840000
5800000
5780000
5760000
5740000
5720000
5200739
5200711
5200709
5700000
5200663
Mean value
5820000
Annex B: Results of homogeneity study
Page 33 of 78
i-Butane
(counts)
sample ID value #1
5200663 21700
5200709 21744
5200711 21712
5200739 21708
value #2 value #3
21699
21702
21739
21754
21706
21714
21701
21706
Statistics (raw)
m
21718
sr
5
s bb
21
sR
22
p
4
Median
21709
MAD
13
AAD
16
value #4
21707
21752
21714
21709
value #5
21705
21757
21710
21713
mean
21703
21749
21711
21707
0.022%
0.10%
0.10%
0.06%
0.07%
21900
21850
21800
21700
21650
21600
21550
5200739
5200711
5200709
21500
5200663
Mean value
21750
s
3
7
3
4
n
5
5
5
5
Annex B: Results of homogeneity study
Page 34 of 78
n-Butane
(counts)
sample ID value #1
5200663 2305.4
5200709 2306.0
5200711 2304.4
5200739 2305.0
value #2 value #3
2298.4
2302.0
2305.9
2310.1
2301.3
2306.2
2304.3
2305.4
Statistics (raw)
m
2304.9
sr
2.2
s bb
2.3
sR
3.2
p
4
Median
2304.4
MAD
1.8
AAD
1.8
value #4
2302.4
2306.6
2303.3
2306.2
value #5
2303.4
2312.6
2303.4
2305.0
mean
2302.3
2308.2
2303.7
2305.2
0.10%
0.10%
0.14%
0.08%
0.08%
2350
2340
2330
2320
2300
2290
2280
2270
2260
5200739
5200711
5200709
2250
5200663
Mean value
2310
s
2.6
3.0
1.8
0.7
n
5
5
5
5
Annex B: Results of homogeneity study
Page 35 of 78
i-Pentane
(counts)
sample ID value #1
5200663 6895.6
5200709 6910.7
5200711 6898.6
5200739 6896.8
value #2 value #3
6896.9
6896.5
6908.8
6913.4
6895.9
6899.5
6896.7
6897.6
Statistics (raw)
m
6901
sr
1.4
s bb
7
sR
7
p
4
Median
6898
MAD
4
AAD
5
value #4
6896.8
6913.1
6898.6
6896.4
value #5
6897.2
6912.6
6900.6
6898.1
mean
6896.6
6911.7
6898.6
6897.1
0.020%
0.10%
0.11%
0.06%
0.08%
6950
6940
6930
6920
6900
6890
6880
6870
6860
5200739
5200711
5200709
6850
5200663
Mean value
6910
s
0.6
1.9
1.7
0.7
n
5
5
5
5
Annex B: Results of homogeneity study
Page 36 of 78
n-Pentane (counts)
sample ID value #1
5200663 2152.6
5200709 2155.4
5200711 2153.8
5200739 2151.6
value #2 value #3
2152.3
2152.4
2155.5
2158.5
2151.5
2154.1
2152.9
2152.6
Statistics (raw)
m
2153.7
sr
1.2
s bb
2.3
sR
2.6
p
4
Median
2152.7
MAD
1.4
AAD
1.8
value #4
2152.1
2157.8
2151.3
2152.0
value #5
2151.9
2159.1
2154.0
2153.2
mean
2152.3
2157.3
2152.9
2152.4
0.05%
0.11%
0.12%
0.06%
0.08%
2190
2180
2170
2150
2140
2130
5200739
5200711
5200709
2120
5200663
Mean value
2160
s
0.3
1.7
1.4
0.6
n
5
5
5
5
Annex B: Results of homogeneity study
Page 37 of 78
Results for the MR composition
Nitrogen
(counts)
sample ID value #1
5200714
4917
5200746
4921
5200679
4912
5200713
4910
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
value #2 value #3
4916
4911
4920
4914
4915
4909
4909
4906
4909
11
6
12
4
4910
6
6
value #4
4875
4917
4913
4905
value #5
4878
4915
4911
4906
mean
4899
4917
4912
4907
0.22%
0.12%
0.25%
0.12%
0.12%
4980
4960
4940
4900
4880
4860
4840
4820
5200713
5200679
4800
5200746
Mean value
4920
5200714
B3
s
21
3
2
2
n
5
5
5
5
Annex B: Results of homogeneity study
Page 38 of 78
Methane
(counts)
sample ID
5200714
5200746
5200679
5200713
value #1
1094602
1095442
1095139
1095175
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
1095200
153
387
416
4
1095385
204
294
value #2 value #3
1094558 1094540
1095528 1095325
1095609 1095564
1095389 1095342
value #4
1094630
1095186
1095406
1095533
value #5
1094730
1095612
1095235
1095461
mean
s n
1094612
75 5
1095418 168 5
1095390 203 5
1095380 135 5
0.014%
0.035%
0.038%
0.019%
0.027%
1100000
1099000
1098000
1097000
1095000
1094000
1093000
1092000
1091000
5200713
5200679
5200746
1090000
5200714
Mean value
1096000
Annex B: Results of homogeneity study
Page 39 of 78
Ethane
(counts)
sample ID
5200714
5200746
5200679
5200713
value #1
892563
893162
892946
892848
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
892937
118
298
321
4
893025
199
217
value #2 value #3
892608
892509
893289
893110
893228
893246
892945
892934
value #4
892448
893067
893065
893109
value #5
892393
893346
892906
893023
mean
892504
893195
893078
892972
0.013%
0.033%
0.036%
0.022%
0.024%
895000
894500
894000
893500
892500
892000
891500
891000
890500
5200713
5200679
5200746
890000
5200714
Mean value
893000
s
86
119
156
98
n
5
5
5
5
Annex B: Results of homogeneity study
Page 40 of 78
Propane
(counts)
sample ID
5200714
5200746
5200679
5200713
value #1
532130
532533
532390
532413
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
532381
72
190
203
4
532443
114
140
value #2 value #3
532133
532068
532571
532471
532534
532505
532438
532423
value #4
532088
532419
532417
532516
value #5
532084
532695
532326
532468
mean
532101
532538
532435
532452
0.014%
0.036%
0.038%
0.021%
0.026%
535000
534500
534000
533500
532500
532000
531500
531000
530500
5200713
5200679
5200746
530000
5200714
Mean value
533000
s
29
105
85
42
n
5
5
5
5
Annex B: Results of homogeneity study
Page 41 of 78
Results for sulphur components in methane
Hydrogen sulphide
(counts)
sample ID value #1
5602449 567.1
5602417 575.6
5601135 582.7
5601766 576.0
value #2 value #3
563.2
565.9
574.3
572.6
581.0
572.9
581.2
577.0
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
575
3.1
6
7
4
577
5
5
value #4
568.3
578.9
582.1
583.9
value #5
564.3
571.9
577.7
578.8
mean
565.7
574.7
579.3
579.4
s
2.1
2.8
4.1
3.2
0.5%
1.1%
1.2%
0.8%
0.8%
640
620
600
560
540
520
500
5601766
5602417
480
5602449
Mean value
580
5601135
B4
n
5
5
5
5
Annex B: Results of homogeneity study
Page 42 of 78
Dimethyl sulphide
(counts)
sample ID value #1
5602449 236.9
5602417 240.1
5601135 239.9
5601766 240.4
value #2 value #3
235.3
236.3
237.6
238.5
243.7
237.2
243.6
242.1
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
239.2
1.9
2.0
2.8
4
239.4
1.4
1.4
value #4
239.4
240.9
238.8
239.1
value #5
234.1
239.0
238.5
242.9
mean
236.4
239.2
239.6
241.6
0.8%
0.8%
1.2%
0.6%
0.6%
280
270
260
250
230
220
210
200
190
5601766
5601135
5602417
180
5602449
Mean value
240
s
2.0
1.3
2.5
1.8
n
5
5
5
5
Annex B: Results of homogeneity study
Page 43 of 78
Ethyl mercaptane
(counts)
sample ID value #1
5602449 437.7
5602417 441.7
5601135 446.1
5601766 438.1
value #2 value #3
436.6
436.9
438.7
436.9
452.0
440.1
445.3
444.7
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
441
3.2
3.2
5
4
441.8
2.6
2.6
value #4
439.5
444.5
446.0
443.7
value #5
434.5
440.7
441.4
443.3
mean
437.1
440.5
445.1
443.0
0.7%
0.7%
1.0%
0.6%
0.6%
480
470
460
450
430
420
410
400
390
5601766
5601135
5602417
380
5602449
Mean value
440
s
1.8
2.9
4.7
2.9
n
5
5
5
5
Annex B: Results of homogeneity study
Page 44 of 78
Methyl mercaptane
(counts)
sample ID value #1
5602449 328.6
5602417 336.3
5601135 340.4
5601766 333.4
value #2 value #3
336.8
336.6
335.2
336.7
334.7
337.3
330.2
331.6
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
335.3
2.3
2.7
3.5
4
335.9
2.1
2.1
value #4
336.1
337.6
338.3
331.2
value #5
337.1
338.2
338.5
330.4
mean
335.0
336.8
337.8
331.4
0.7%
0.8%
1.0%
0.6%
0.6%
390
370
330
310
290
5601766
5601135
5602417
270
5602449
Mean value
350
s
3.6
1.2
2.1
1.3
n
5
5
5
5
Annex B: Results of homogeneity study
Page 45 of 78
Carbonyl sulphide
(counts)
sample ID value #1
5602449 244.6
5602417 242.4
5601135 239.4
5601766 231.9
value #2 value #3
241.2
243.2
242.7
243.8
240.7
235.5
234.7
232.3
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
239
1.6
5
5
4
240.3
3.4
3.4
value #4
241.9
243.5
239.3
232.5
value #5
240.6
240.6
237.1
232.5
mean
242.3
242.6
238.4
232.8
0.7%
1.9%
2.0%
1.4%
1.4%
280
270
260
250
230
220
210
200
190
5601766
5601135
5602417
180
5602449
Mean value
240
s
1.6
1.3
2.1
1.1
n
5
5
5
5
Annex B: Results of homogeneity study
Page 46 of 78
Total sulphur
(counts)
sample ID value #1
5602449
1745
5602417
1762
5601135
1771
5601766
1748
value #2 value #3
1733
1744
1756
1753
1786
1749
1769
1761
Statistics
m
sr
s bb
sR
p
Median
MAD
AAD
1757
10
10
14
4
1760
7
8
value #4
1753
1775
1772
1765
value #5
1732
1753
1760
1761
mean
1741
1760
1767
1761
0.6%
0.6%
0.8%
0.4%
0.5%
2000
1900
1700
1600
1500
5601766
5601135
5602417
1400
5602449
Mean value
1800
s
9
9
14
8
n
5
5
5
5
Page 47 of 78
Annex C: Procedure for statistical analysis and
evaluation of laboratory results
Annex C: Procedure for statistical analysis and evaluation of laboratory results
Page 48 of 78
C1
Determination of consensus values
The determination of the consensus value is carried out according to an adapted procedure that is described in the
subsequent paragraphs. Classical, as well as robust estimates are determined.
The data are treated analogous to the procedures described in ISO 5725–1 and –2 [C1, C2]. First, from the complete
set of the reported data the grand mean ( m̂ ), the repeatability standard deviation (sr), the between-laboratory
standard deviation (sL) and the reproducibility standard deviation (sR) are calculated.
The consensus value is defined according to:
p
ˆ
m
ni y i
i 1
p
y
(C1)
ni
i 1
where ni equals the number of results reported by laboratory i, y i the average result of this laboratory and p is the
total number of laboratories. The repeatability standard deviation is follows from:
p
1 si2
ni
sr2
i 1
p
(C2)
ni
1
i 1
where si is the repeatability standard deviation of the results of laboratory i.
The between-laboratory standard deviation is calculated according to:
sL2
sd2
sr2
(C3)
n
where
p
2
p
1
sd2
ni y i
1i
y
(C4)
1
is identical to MSamong resulting from the unifactoral analysis of variance (see also annex A).
n
is defined as
p
n
p
1
p
1
ni
i 1
ni2
i 1
p
(C5)
ni
i 1
The reproducibility standard deviation is calculated according to:
sR2
sL2 sr2
(C6)
The complete data set is also used to calculate a number of robust estimates: the median (ymed), the median of
absolute differences (MAD) and the average absolute deviation (AAD).
The absolute differences are calculated according to:
di
yi
y med
(C7)
and the average absolute deviation according to:
AAD
1
p
p
di
i 1
(C8)
Annex C: Procedure for statistical analysis and evaluation of laboratory results
Page 49 of 78
The procedure for checking on outliers is different from the methods described in ISO 5725-2. Outliers are defined
as follows. From the laboratory averages, y i , a standard deviation, s, is calculated. This standard deviation is used
to calculate a raw Z-score, according to:
ˆ
m
yi
Z raw ,i
(C9)
s
In case Zraw,i is larger than 2, the result concerned ( y i ) is removed from the data set.
Applying equations (C1), (C2), (C3) and (C5), from the cleared data set the consensus values are recalculated.
A different method for outlier testing from the ones described in ISO 5725-2 was chosen, because the methods
described in this standard are sensitive towards asymmetry and non-normality of data sets. The method applied as
described above, works better on asymmetric data sets. Also the method does not have the limitation of a Grubbs’
test that no more than two outliers on one side of the distribution may be removed. Frequently, this limitation finds its
justification in the fact that removing outliers on one side of the distribution only may be a reason for biased
consensus values. In practice, however, there may be good reasons for removing outliers only on one side of the
distribution.
C2
Qualification of the laboratory results
For qualification of the laboratory results, Z-scores are calculated. The value is a measure for the relative distance
from the reference value.
The Z-score for parameter i, Zi, is calculated according to:
Zi
yi
y ref
ˆ
(C10)
where, yref is the reference value for the parameter, and ˆ is the standard deviation for evaluation. This value is
calculated from the coefficient of variation for evaluation, CVev, according to:
ˆ
CVev
(C11)
y ref
The values of CVev are listed in Table C1.
The qualification of the results is the following:
|Z| < 2
2 < |Z| < 3
|Z| > 3
Satisfactory result
Questionable result
Unsatisfactory result
Including the uncertainties reported by the laboratories, En–values can be used for qualification of the laboratory
results.
The En–value is calculated according to:
En
yi
2
Uref
y ref
2
Ustat
,i
(C12)
Annex C: Procedure for statistical analysis and evaluation of laboratory results
Page 50 of 78
where Uref is the expanded uncertainty (k=2) of the reference value and Ustat,I is the expanded uncertainty (k=2)
stated by the laboratory.
The qualification of the results is the following:
|En| < 1
Satisfactory result
|En| > 1
Unsatisfactory result
Table C1: Values for coefficient of variation for evaluation
LNG composition
Propane composition
MR composition
Ethane
1.1%
Ethane
2.0%
Ethane
1.0%
Propane
1.1%
i-Butane
2.5%
Propane
1.5%
i-Butane
2.2%
n-Butane
2.5%
Nitrogen
1.5%
n-Butane
2.2%
i-Pentane
3.0%
Methane
1.0%
i-Pentane
2.2%
n-Pentane
3.0%
n-Pentane
2.2%
Nitrogen
3.0%
Hexane
0.22/x%*
Propane
0.1%
Nitrogen
Carbon dioxide
Methane
Sulphur components in
methane
Hydrogen
3.0%
sulphide
Dimethyl
sulphide
3.0%
Ethyl
mercaptane
3.0%
Methyl
mercaptane
3.0%
1.1%
2.2%**
1.1%***
0.1%
Carbonyl
sulphide
Total sulphur
3.0%
5.0%
*x = amount of substance fraction of hexane in %mol/mol
**for an amount of substance fraction between 0.1 and 1 % mol/mol
***for an amount of substance fraction between 1 and 8 % mol/mol
C3
References
[C1]
International Organization for Standardization, “ISO 5725-1:1994 Accuracy (trueness and precision) of
measurement methods and results - Part 1: General principles and definition”, Statistical methods for quality
control Vol. 2 (1994), pp. 9-29
[C2]
International Organization for Standardization, “ISO 5725-2:1994 Accuracy (trueness and precision) of
measurement methods and results - Part 2: Basic method for the determination of repeatability and
reproducibility of a standard measurement method”, Statistical methods for quality control, Vol. 2 (1994), pp.
30-74
Annex C: Procedure for statistical analysis and evaluation of laboratory results
Page 51 of 78
Annex D: Laboratory results and evaluation
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 52 of 78
Results for the LNG composition
std. dev.
83.71
83.55
83.76
83.86
0.009
0.022 N/A
0.004
0.0025
83.97
0.026 N/A
0.21
0.29
0.20
0.00028
0.08
N/A
flag
Z raw
Z
En
-0.52
-1.69
-0.10
0.67
0.13
-1.70
0.78
1.99
1.50
3.27
-0.33
-0.41
0.42
0.29
0.03
0.16
0.47
0.11
Results for Methane
0.020%
sL
0.16
0.19%
sR
0.16
0.19%
7
83.73
0.07
0.10
0.08%
0.12%
85.0
84.5
84.0
13
13
82.0
12
0.19%
7
12
0.16
11
sR
82.5
11
0.19%
10
0.16
83.0
10
sL
83.5
9
Consensus values (corrected)
m
83.77
sr
0.017
0.020%
p
n
0
2
5
3
5
0
5
0
2
1
8
83.73
83.72
Consensus values (raw)
m
83.77
sr
0.017
p
Median
MAD
AAD
U (k=2)
7
value
6
lab
2
3
6
7
8
9
10
11
12
13
(%, mol/mol)
3
Methane
Reported data
2
D1
Z-scores for Methane
Reference values
y ref
83.70
U ref (k=2)
0.29
4
3
2
1
0
-1
-2
-3
9
8
7
6
3
-4
2
Standard deviation for evaluation
ˆ
0.084
CV
0.10%
Laboratory Code
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 53 of 78
Ethane
Reported data
lab
2
3
6
7
8
9
10
11
12
13
(%, mol/mol)
value
std. dev.
8.025
8.17
8.01
7.912
0.0035
0.007 N/A
0.004
0.0020
8.02
0.016 N/A
8.031
8.02
Consensus values (raw)
m
8.03
sr
0.009
0.0006
0.054
0.15
0.027
0.070
flag
Z raw
Z
En
-0.06
1.86
-0.20
-1.57
-0.17
1.47
-0.29
-1.45
-0.14
-0.24
0.02
-0.08
-0.10
-0.18
-0.22
-0.16
-2.64
-0.11
Results for Ethane
0.11%
0.09
1.2%
sR
0.09
1.2%
7
8.02
0.011
0.04
n
0
2
5
3
5
0
5
0
2
1
N/A
sL
p
Median
MAD
AAD
U (k=2)
8.4
8.3
8.2
0.14%
0.5%
8.1
8.0
12
13
13
2
12
7.6
11
1.2%
7
11
0.09
p
10
7.7
9
1.2%
8
0.09
sR
7
sL
6
7.8
3
7.9
Consensus values (corrected)
m
8.03
sr
0.009
0.11%
Z-scores for Ethane
Reference values
y ref
8.040
U ref (k=2)
0.040
4
3
2
1
0
-1
-2
-3
Laboratory Code
10
9
8
7
6
3
-4
2
Standard deviation for evaluation
ˆ
0.088
CV
1.1%
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 54 of 78
Propane
Reported data
lab
2
3
6
7
8
9
10
11
12
13
(%, mol/mol)
value
std. dev.
3.29
3.286
3.285
3.259
0.0026
0.005 N/A
0.0009
0.0011
3.323
0.006 N/A
3.285
3.29
Consensus values (raw)
m
3.288
sr
0.004
0.0006
0.11
0.039
0.024
0.035
flag
Z raw
Z
En
-0.04
-0.13
-0.18
-1.56
-0.18
-0.23
-0.25
-0.96
1.85
0.79
-0.19
0.24
-0.26
-0.03
-0.06
-0.22
-1.20
-0.24
Results for Propane
0.13%
0.023
0.7%
sR
0.024
0.7%
7
3.286
0.0035
0.011
n
0
2
5
3
5
0
5
0
2
1
N/A
sL
p
Median
MAD
AAD
U (k=2)
3.50
3.45
3.40
0.11%
0.34%
3.35
3.30
12
13
13
2
12
3.10
11
0.7%
7
11
0.024
p
10
3.15
9
0.7%
8
0.023
sR
7
sL
6
3.20
3
3.25
Consensus values (corrected)
m
3.288
sr
0.004
0.13%
Z-scores for Propane
Reference values
y ref
3.294
U ref (k=2)
0.016
4
3
2
1
0
-1
-2
-3
Laboratory Code
10
9
8
7
6
3
-4
2
Standard deviation for evaluation
ˆ
0.036
CV
1.1%
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 55 of 78
i-Butane
Reported data
lab
2
3
6
7
8
9
10
11
12
13
(%, mol/mol)
value
std. dev.
0.798
0.810
0.784
0.7981
0.705
0.7906
0.799
Consensus values (raw)
m
0.78
sr
0.0036
U (k=2)
0.0007
0.025
0.007 N/A
0.0004
0.008
0.00028
0.0072
0.0014 N/A
0.00021
0.0069
N/A
flag
Z raw
*
Z
En
0.56
0.90
0.17
0.57
-0.05
0.65
-0.83
-0.03
-2.05
-5.33
0.35
0.59
-0.46
0.02
-0.04
-1.52
-0.06
-0.94
Results for i-Butane
0.5%
0.90
sL
0.04
6%
0.88
sR
0.04
6%
0.86
7
0.798
0.020
0.026
2.5%
3.3%
p
Median
MAD
AAD
n
0
2
5
3
5
0
5
0
2
1
0.84
0.82
0.80
0.78
0.76
12
13
12
13
2
6
11
0.70
p
10
0.72
1.3%
9
1.2%
0.010
8
0.010
sR
7
sL
6
0.74
3
Consensus values (corrected)
m
0.798
sr
0.004
0.5%
Z-scores for i-Butane
Reference values
y ref
0.7986
U ref (k=2)
0.0050
4
3
2
1
0
-1
-2
-3
Laboratory Code
11
10
9
8
7
6
3
-4
2
Standard deviation for evaluation
ˆ
0.018
CV
2.2%
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 56 of 78
n-Butane
Reported data
lab
2
3
6
7
8
9
10
11
12
13
(%, mol/mol)
value
std. dev.
U (k=2)
0.905
0.910
0.889
0.886
0.0008
0.007 N/A
0.0008
0.00036
0.800
0.0016 N/A
0.8883
0.899
Consensus values (raw)
m
0.88
sr
0.0036
0.00021
0.032
0.010
0.009
0.0024
N/A
0.4%
1.00
0.04
5%
0.98
sR
0.04
5%
0.96
7
0.889
0.024
0.029
flag
Z raw
*
Z
En
0.79
0.93
0.36
0.29
0.35
0.61
-0.45
-0.59
-2.01
-4.94
0.34
0.63
-0.49
0.06
0.22
-0.74
-1.11
-1.48
Results for n-Butane
sL
p
Median
MAD
AAD
n
0
2
5
3
5
0
5
0
2
1
0.94
2.7%
3.2%
0.92
0.90
0.88
0.86
12
13
13
2
6
12
0.80
p
11
1.3%
10
0.012
9
0.82
sR
8
1.3%
7
0.011
6
0.84
sL
3
Consensus values (corrected)
m
0.896
sr
0.004
0.5%
Z-scores for n-Butane
Reference values
y ref
0.8979
U ref (k=2)
0.0060
4
3
2
1
0
-1
-2
-3
Laboratory Code
11
10
9
8
7
6
3
-4
2
Standard deviation for evaluation
ˆ
0.020
CV
2.2%
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 57 of 78
i-Pentane
Reported data
lab
2
3
6
7
8
9
10
11
12
13
(%, mol/mol)
value
std. dev.
0.299
0.308
0.3003
0.3076
0.278
0.3010
0.302
Consensus values (raw)
m
0.299
sr
0.0023
U (k=2)
0.00028
0.013
0.004 N/A
0.00029
0.0071
0.00013
0.0026
0.0008 N/A
0.0000
0.0046
N/A
flag
Z raw
*
Z
En
0.04
0.91
0.16
0.88
-0.44
0.90
-0.26
0.84
-2.06
-3.66
0.23
0.33
-0.16
-0.01
-0.23
-0.23
1.57
-0.20
Results for i-Pentane
0.8%
0.35
sL
0.013
4%
sR
0.013
4%
0.33
7
0.301
0.0033
0.007
1.1%
2.2%
0.31
p
Median
MAD
AAD
n
0
2
5
3
5
0
5
0
2
1
0.29
11
12
13
11
12
13
2
10
0.25
6
9
1.5%
p
8
1.3%
0.005
7
0.0039
sR
6
sL
0.27
3
Consensus values (corrected)
m
0.305
sr
0.0026
0.8%
Z-scores for i-Pentane
Reference values
y ref
0.3021
U ref (k=2)
0.0024
4
3
2
1
0
-1
-2
-3
Laboratory Code
10
9
8
7
6
3
-4
2
Standard deviation for evaluation
ˆ
0.0066
CV
2.2%
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 58 of 78
n-Pentane
Reported data
lab
2
3
6
7
8
9
10
11
12
13
(%, mol/mol)
value
std. dev.
0.206
0.202
0.2024
0.2055
0.191
0.1994
0.202
0.0007 N/A
0.0000
0.0017
N/A
1.1%
sL
0.006
2.9%
sR
0.006
3.1%
7
0.2020
0.0020
0.0037
n
0
2
5
3
5
0
5
0
2
1
0.00021
0.008
0.004 N/A
0.00021
0.0047
0.00017
0.0028
Consensus values (raw)
m
0.200
sr
0.0023
p
Median
MAD
AAD
U (k=2)
flag
Z raw
Z
En
1.02
0.30
0.39
1.00
0.88
0.06
0.16
0.86
-1.92
-2.49
-0.21
0.30
-0.53
0.06
0.47
0.14
1.18
-1.00
Results for n-Pentane
0.220
0.215
0.210
1.0%
1.8%
0.205
0.200
3
2
13
0.180
13
3.1%
7
12
0.006
p
12
sR
11
0.185
10
2.9%
9
0.006
8
sL
7
0.190
6
0.195
Consensus values (corrected)
m
0.200
sr
0.0023
1.1%
Z-scores for n-Pentane
Reference values
y ref
0.2017
U ref (k=2)
0.0016
4
3
2
1
0
-1
-2
-3
Laboratory Code
11
10
9
8
7
6
3
-4
2
Standard deviation for evaluation
ˆ
0.0044
CV
2.2%
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 59 of 78
std. dev.
En
-0.49
-0.96
-1.05
1.44
0.67
0.08
-0.04
3.09
0.86
2.36
-1.01
-0.59
0.01
0.54
0.40
-0.02
1.25
0.01
Results for n-Hexane
0.8%
sL
0.0032
6%
sR
0.0032
6%
p
Median
MAD
AAD
7
0.0510
0.0026
0.0025
0.060
0.055
0.040
13
6%
7
13
6%
0.0032
12
0.0032
sR
0.045
12
sL
0.050
11
5%
5%
Consensus values (corrected)
m
0.0526
sr
0.0004
0.8%
p
0.0033
N/A
Z
10
Consensus values (raw)
m
0.0526
sr
0.0004
0.00007
Z raw
9
0.0499
0.0510
0.0008 N/A
flag
8
0.0550
0.0000
0.0037
0.00 N/A
0.00012
0.0051
0.00023
0.0054
n
0
2
5
3
5
0
5
0
2
1
7
0.0513
0.05
0.0497
0.0566
U (k=2)
6
value
2
lab
2
3
6
7
8
9
10
11
12
13
(%, mol/mol)
3
n-Hexane
Reported data
Z-scores for n-Hexane
Reference values
y ref
0.04982
U ref (k=2)
0.00051
4
3
2
1
0
-1
-2
-3
Laboratory Code
11
10
9
8
7
6
3
-4
2
Standard deviation for evaluation
ˆ
0.0022
CV
4.4%
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 60 of 78
std. dev.
0.00028
En
0.96
0.83
0.25
0.38
0.07
0.01
-0.24
-0.19
-1.98
-1.23
0.64
-0.04
-0.07
-0.37
0.15
-0.43
-0.05
-0.14
Results for Carbon dioxide
0.35%
sL
0.008
1.1%
sR
0.008
1.2%
p
Median
MAD
AAD
7
0.705
0.004
0.005
0.6%
0.7%
0.76
0.74
0.72
1.2%
0.64
7
13
0.008
13
sR
0.66
12
1.1%
12
0.008
0.68
11
sL
0.70
11
Consensus values (corrected)
m
0.702
sr
0.0025
0.35%
p
0.0058
N/A
Z
10
Consensus values (raw)
m
0.702
sr
0.0025
0.0019 N/A
Z raw
9
0.7067
0.702
0.00014
0.0053
0.004 N/A
0.00017
0.0072
0.0007
0.058
flag
8
0.6886
n
0
2
5
3
5
0
5
0
2
1
7
0.7089
0.708
0.7040
0.705
U (k=2)
6
value
2
lab
2
3
6
7
8
9
10
11
12
13
(%, mol/mol)
3
Carbon dioxide
Reported data
Z-scores for Carbon dioxide
Reference values
y ref
0.7078
U ref (k=2)
0.0051
4
3
2
1
0
-1
-2
-3
Laboratory Code
10
9
8
7
6
3
-4
2
Standard deviation for evaluation
ˆ
0.016
CV
2.2%
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 61 of 78
Nitrogen
Reported data
lab
2
3
6
7
8
9
10
11
12
13
(%, mol/mol)
value
std. dev.
U (k=2)
2.012
2.000
2.008
2.007
0.0006
0.007 N/A
0.0006
0.004
1.973
0.005 N/A
2.016
2.007
Consensus values (raw)
m
1.999
sr
0.005
0.00035
n
0
2
5
3
5
0
5
0
2
1
0.013
0.040
0.036
0.018
N/A
flag
Z raw
Z
En
0.88
0.04
0.62
0.52
0.04
-0.51
-0.13
-0.19
-1.85
-1.74
1.17
0.52
0.23
-0.19
0.05
-0.07
-0.11
0.25
Results for Nitrogen
0.25%
2.10
sL
0.016
0.8%
2.08
sR
0.017
0.8%
p
Median
MAD
AAD
7
2.007
0.009
0.012
0.4%
0.6%
2.06
2.04
2.02
2.00
1.98
1.96
11
12
13
12
13
2
7
11
1.90
p
10
0.8%
10
0.017
9
1.92
sR
8
0.8%
7
0.016
6
1.94
sL
3
Consensus values (corrected)
m
1.999
sr
0.005
0.25%
Z-scores for Nitrogen
Reference values
y ref
2.011
U ref (k=2)
0.010
4
3
2
1
0
-1
-2
-3
9
8
7
6
3
-4
2
Standard deviation for evaluation
ˆ
0.022
CV
1.1%
Laboratory Code
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 62 of 78
Results for propane composition
Ethane
(%, mol/mol)
Reported data
lab
value
std. dev. U (k=2)
1
2
3
6
2.67
0.011 N/A
7
2.51
0.0027
0.08
8
2.475
0.0025
0.012
9
12
2.516
0.012
0.026
13
15
2.37
0.32 N/A
flag
n
0
0
0
5
3
5
0
2
0
3
Z raw
-0.04
0.12
0.18
-1.43
-2.85
2.5
2.4
2.3
12
13
15
12
13
15
9
2.2
8
5%
3.7%
6%
2.6
7
2.52
0.13
0.09
0.16
5
0.00
-1.35
2.7
3
1.8%
2.9%
Consensus values (corrected)
m
sr
sL
sR
p
3.11
0.01
-0.69
2.8
2
5%
3.7%
6%
1
2.52
0.13
0.09
0.16
5
2.51
0.05
0.07
En
Results for Ethane
Consensus values (raw)
m
sr
sL
sR
p
Median
MAD
AAD
Z
1.36
-0.10
-0.42
6
D2
Z-scores for Ethane
Reference values
y ref
2.510
U ref (k=2)
0.023
4
3
2
1
0
-1
-2
-3
Laboratory Code
9
8
7
6
3
2
-4
1
Standard deviation for
evaluation
ˆ
0.050
CV
2.0%
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 63 of 78
Propane
(%, mol/mol)
Reported data
lab
value
std. dev. U (k=2)
1
2
3
6
96.78
0.013 N/A
7
96.96
0.0028
0.40
8
97.00
0.0030
0.16
9
12
96.899
0.017
0.040
13
15
97.13
0.23 N/A
flag
n
0
0
0
5
3
5
0
2
0
3
0.09%
0.13%
0.16%
-1.86
-0.03
0.45
0.00
0.08
-0.33
-0.61
-0.11
1.46
1.80
98.5
0.06%
0.10%
97.5
97.0
96.5
96.0
95.5
9
12
13
15
9
12
13
15
8
7
6
95.0
3
0.09%
0.13%
0.16%
2
96.94
0.09
0.13
0.16
5
-1.26
0.10
0.46
98.0
Consensus values (corrected)
m
sr
sL
sR
p
En
99.0
1
96.94
0.09
0.13
0.16
5
96.96
0.06
0.09
Z
Results for Propane
Consensus values (raw)
m
sr
sL
sR
p
Median
MAD
AAD
Z raw
Z-scores for Propane
Reference values
y ref
96.96
U ref (k=2)
0.53
4
3
2
1
0
-1
-2
-3
8
7
6
3
2
-4
1
Standard deviation for
evaluation
ˆ
0.097
CV
0.10%
Laboratory Code
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 64 of 78
i-Butane
(%, mol/mol)
Reported data
lab
value
std. dev. U (k=2)
1
2
3
6
0.31
0.00 N/A
7
0.303
0.00021
0.025
8
0.296
0.00035
0.012
9
12
0.3096
0.0016
0.0033
13
15
0.3
0.0 N/A
flag
n
0
0
0
5
3
5
0
2
0
3
Z raw
0.07
-0.41
1.05
1.17
1.98
-0.50
-0.10
0.30
0.29
0.28
13
15
13
15
12
9
8
0.27
7
0.16%
2.2%
2.2%
0.31
6
0.303
0.00050
0.007
0.007
5
1.23
0.23
-0.66
0.32
3
2.1%
1.6%
Consensus values (corrected)
m
sr
sL
sR
p
1.12
-0.09
-1.19
0.33
2
0.16%
2.2%
2.2%
1
0.303
0.00050
0.007
0.007
5
0.303
0.006
0.005
En
Results for i-Butane
Consensus values (raw)
m
sr
sL
sR
p
Median
MAD
AAD
Z
Z-scores for i-Butane
Reference values
y ref
0.3008
U ref (k=2)
0.0030
4
3
2
1
0
-1
-2
-3
Laboratory Code
12
9
8
7
6
3
2
-4
1
Standard deviation for
evaluation
ˆ
0.0075
CV
2.5%
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 65 of 78
n-Butane
(%, mol/mol)
Reported data
lab
value
std. dev. U (k=2)
1
2
3
6
0.03
0.00 N/A
7
0.0305
0.0000
0.0028
8
0.032
0.00031
0.015
9
12
0.0315
0.00028
0.0056
13
15*
flag
n
0
0
0
5
3
5
0
2
0
Z raw
0.04
0.11
0.53
1.47
0.20
0.030
0.029
0.028
13
15
*
13
15*
12
9
8
0.027
7
0.7%
3.4%
3.5%
0.031
6
0.0310
0.00021
0.0011
0.0011
4
-0.50
0.16
2.26
0.032
3
2.4%
2.5%
Consensus values (corrected)
m
sr
sL
sR
p
-1.05
-0.53
1.16
0.033
2
0.7%
3.4%
3.5%
1
0.0310
0.00021
0.0011
0.0011
4
0.0310
0.0008
0.0008
En
Results for n-Butane
Consensus values (raw)
m
sr
sL
sR
p
Median
MAD
AAD
Z
Z-scores for n-Butane
Reference values
y ref
0.03038
U ref (k=2)
0.00030
4
3
2
1
Standard deviation for
evaluation
ˆ
0.00076
CV
2.5%
0
-1
-2
-3
Laboratory Code
*Lab 15 has reported 3 values: <0.1, <0.1 and 0.2 % mol/mol
12
9
8
7
6
3
2
1
-4
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 66 of 78
i-Pentane
(%, mol/mol)
Reported data
lab
value
std. dev. U (k=2)
1
2
3
6
0.08
0.00 N/A
7
0.0757 0.00006
0.0026
8
0.0737 0.000023
0.0034
9
12
0.0746
0.0004
0.0009
13
15
0.1
0.0 N/A
flag
n
0
0
0
5
3
5
0
2
0
3
Z raw
0.080
0.00012
0.010
0.010
5
0.076
0.006
0.007
En
-0.02
-0.42
-0.60
1.99
0.08
-0.79
0.06
-0.51
-0.51
-0.40
-0.78
1.79
10.82
Results for i-Pentane
Consensus values (raw)
m
sr
sL
sR
p
Median
MAD
AAD
Z
0.15%
13%
13%
0.085
0.080
7%
10%
0.075
Consensus values (corrected)
0.070
13
15
13
15
12
9
8
7
6
0.065
3
0.15%
13%
13%
2
0.0803
0.00012
0.010
0.010
5
1
m
sr
sL
sR
p
Z-scores for i-Pentane
Reference values
y ref
0.07550
U ref (k=2)
0.00072
4
3
2
1
0
-1
-2
-3
Laboratory Code
12
9
8
7
6
3
2
-4
1
Standard deviation for
evaluation
ˆ
0.0023
CV
3.0%
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 67 of 78
n-Pentane
(%, mol/mol)
Reported data
lab
value
std. dev. U (k=2)
1
2
3
6
0.02
0.00 N/A
7
0.0229
0.00000
0.0023
8
0.0219 0.000034
0.0036
9
12
0.0227
0.00028
0.0010
13
15
<0.1
N/A
flag
n
0
0
0
5
3
5
0
2
0
Z raw
0.0216
0.00009
0.0014
0.0014
4
0.0223
0.0012
0.0011
En
-1.18
1.01
0.23
-4.06
0.18
-1.32
0.05
-0.25
0.86
-0.11
-0.07
Results for n-Pentane
Consensus values (raw)
m
sr
sL
sR
p
Median
MAD
AAD
Z
0.4%
6%
6%
0.026
0.025
0.024
6%
5%
0.023
0.022
0.020
13
15
13
15
12
9
8
7
0.019
6
0.4%
6%
6%
0.021
3
0.0216
0.00009
0.0014
0.0014
4
2
m
sr
sL
sR
p
1
Consensus values (corrected)
Z-scores for n-Pentane
Reference values
y ref
0.02277
U ref (k=2)
0.00022
4
3
2
1
0
-1
-2
-3
Laboratory Code
12
9
8
7
6
3
2
-4
1
Standard deviation for
evaluation
ˆ
0.00068
CV
3.0%
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 68 of 78
Nitrogen
(%, mol/mol)
Reported data
lab
value
std. dev. U (k=2)
1
2
3
6
0.102
0.004 N/A
7
0.102
0.00020
0.049
8
0.0988
0.00023
0.0044
9
12
0.147
0.0035
0.009
13
15
< 0.1
flag
n
0
0
0
5
3
5
0
2
0
-0.07
0.03
-1.10
0.00
-0.74
1.74
14.51
4.75
0.12
0.11
0.10
9
12
13
15
9
12
13
15
8
0.09
7
2.7%
17%
17%
0.13
6
0.107
0.0029
0.018
0.019
4
-0.22
-0.20
-0.36
0.14
3
6%
14%
Consensus values (corrected)
m
sr
sL
sR
p
En
0.15
2
2.7%
17%
17%
1
0.107
0.0029
0.018
0.019
4
0.102
0.007
0.014
Z
Results for Nitrogen
Consensus values (raw)
m
sr
sL
sR
p
Median
MAD
AAD
Z raw
Z-scores for Nitrogen
Reference values
y ref
0.1022
U ref (k=2)
0.0011
4
3
2
1
0
-1
-2
-3
8
7
6
3
2
-4
1
Standard deviation for
evaluation
ˆ
0.0031
CV
3.0%
Laboratory Code
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 69 of 78
Results for MR composition
Methane
(%, mol/mol)
Reported data
lab
value
std. dev. U (k=2)
2
8.04
0.010 N/A
3
6
57.32
0.035 N/A
7
56.9
0.024
1.3
8
56.58
0.006
0.41
9
12
56.83
0.005
0.40
13
14
56.74
0.14 N/A
flag
n
5
0
5
3
5
0
2
0
5
0.63
-0.05
-0.67
-0.02
-0.77
0.49
-0.23
-0.27
0.48
-0.38
57
56
55
12
13
14
12
13
14
54
9
0.14%
46%
46%
58
8
47
0.06
22
22
6
0.51
0.49
0.47
59
6
17%
26%
Consensus values (corrected)
m
sr
sL
sR
p
En
60
3
0.14%
46%
46%
2
47
0.06
22
22
6
57
10
15
Z
-85.88
Results for Methane
Consensus values (raw)
m
sr
sL
sR
p
Median
MAD
AAD
Z raw
-1.96
7
D3
Z-scores for Methane
Reference values
y ref
56.96
U ref (k=2)
0.28
4
3
2
1
0
-1
-2
-3
9
8
7
6
3
-4
2
Standard deviation for
evaluation
ˆ
0.57
CV
1.0%
Laboratory Code
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 70 of 78
Ethane
(%, mol/mol)
Reported data
lab
value
std. dev. U (k=2)
2
46.20
0.019 N/A
3
6
24.99
0.011 N/A
7
25.00
0.016
0.58
8
25.36
0.0020
0.43
9
12
25.16
0.004
0.36
13
14
24.75
0.05 N/A
flag
n
5
0
5
3
5
0
2
0
5
29
0.027
9
9
6
25
4
6
Z
84.64
En
-0.50
-0.49
-0.45
-0.14
-0.07
1.37
-0.03
0.76
-0.48
0.57
0.38
-0.52
-1.09
Results for Ethane
Consensus values (raw)
m
sr
sL
sR
p
Median
MAD
AAD
Z raw
1.96
0.09%
32%
32%
26.0
25.8
25.6
25.4
17%
25%
25.2
25.0
24.8
24.4
24.2
9
12
13
14
9
12
13
14
8
24.0
7
0.09%
32%
32%
24.6
6
29
0.027
9
9
6
3
m
sr
sL
sR
p
2
Consensus values (corrected)
Z-scores for Ethane
Reference values
y ref
25.02
U ref (k=2)
0.12
4
3
2
1
0
-1
-2
-3
8
7
6
3
-4
2
Standard deviation for
evaluation
ˆ
0.25
CV
1.0%
Laboratory Code
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 71 of 78
Propane
(%, mol/mol)
Reported data
lab
value
std. dev. U (k=2)
2
29.93
0.008 N/A
3
6
9.86
0.036 N/A
7
10.03
0.010
0.46
8
10.05
0.0029
0.14
9
12
9.95
0.0006
0.09
13
14
9.85
0.036 N/A
flag
n
5
0
5
3
5
0
2
0
5
14
0.024
9
9
6
10
4
6
Z
133.01
En
-0.50
-0.48
-0.48
-0.87
0.25
0.38
0.08
0.39
-0.49
-0.28
-0.39
-0.50
-0.96
Results for Propane
Consensus values (raw)
m
sr
sL
sR
p
Median
MAD
AAD
Z raw
1.96
0.17%
63%
63%
10.5
10.4
10.3
10.2
40%
60%
10.1
10.0
9.9
9.7
9.6
9
12
13
14
9
12
13
14
8
9.5
7
0.17%
63%
63%
9.8
6
14
0.024
9
9
6
3
m
sr
sL
sR
p
2
Consensus values (corrected)
Z-scores for Propane
Reference values
y ref
9.992
U ref (k=2)
0.051
4
3
2
1
0
-1
-2
-3
8
7
6
3
-4
2
Standard deviation for
evaluation
ˆ
0.15
CV
1.5%
Laboratory Code
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 72 of 78
Nitrogen
(%, mol/mol)
Reported data
lab
value
std. dev. U (k=2)
2
15.83
0.017 N/A
3
6
7.83
0.017 N/A
7
8.04
0.0018
0.30
8
8.012
0.0021
0.048
9
12
8.06
0.010
0.14
13
14
8.05
0.06 N/A
flag
n
5
0
5
3
5
0
2
0
5
9.6
0.029
3.5
3.5
6
8.0
1.5
2.3
Z
64.77
En
-0.54
-0.47
-0.48
-1.63
0.07
-0.15
0.03
-0.25
-0.47
0.24
0.19
-0.47
0.17
Results for Nitrogen
Consensus values (raw)
m
sr
sL
sR
p
Median
MAD
AAD
Z raw
1.96
0.30%
36%
36%
8.5
8.4
8.3
8.2
19%
29%
8.1
8.0
7.9
7.7
7.6
12
13
14
12
13
14
9
8
7.5
7
0.30%
36%
36%
7.8
6
9.6
0.029
3.5
3.5
6
3
m
sr
sL
sR
p
2
Consensus values (corrected)
Z-scores for Nitrogen
Reference values
y ref
8.030
U ref (k=2)
0.057
4
3
2
1
0
-1
-2
-3
9
8
7
6
3
-4
2
Standard deviation for
evaluation
ˆ
0.12
CV
1.5%
Laboratory Code
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 73 of 78
D4
Results for sulphur components in methane
Hydrogen sulphide
(µmol/mol)
Reported data
lab
value
std. dev. U (k=2)
1
2
3
35.6
0.4
3.6
4
36.46
0.11
0.37
5
6
7
36.1
0.5
2.4
8
9
12
65.0
1.3
2.7
13
flag
n
0
0
2
7
0
0
3
0
0
2
0
1.2%
31%
31%
0.00
0.81
0.00
0.66
-0.29
0.50
0.20
1.70
27.50
9.75
65
12%
26%
55
50
45
40
35
9
12
13
9
12
13
8
7
6
5
4
30
3
1.2%
31%
31%
2
40
0.5
12
12
4
-0.33
-0.27
60
Consensus values (corrected)
m
sr
sL
sR
p
En
70
1
40
0.5
12
12
4
36
4
9
Z
Results for Hydrogen sulphide
Consensus values (raw)
m
sr
sL
sR
p
Median
MAD
AAD
Z raw
Z-scores for Hydrogen sulphide
Reference values
y ref
35.6
U ref (k=2)
1.3
4
3
2
1
0
-1
-2
-3
Laboratory Code
8
7
6
5
4
3
2
-4
1
Standard deviation for
evaluation
ˆ
1.1
CV
3.0%
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 74 of 78
Dimethyl sulphide
(µmol/mol)
Reported data
lab
value
std. dev. U (k=2)
3
4
5
6
7
14.5
0.10
1.1
8
9
12
22.3
0.56
2.3
13
flag
n
0
0
0
0
3
0
0
2
0
Z raw
18
0.33
5
5
2
18.4
3.9
3.9
En
-0.57
-0.95
-0.35
0.85
16.39
3.15
Results for Dimethyl sulphide
Consensus values (raw)
m
sr
sL
sR
p
Median
MAD
AAD
Z
1.9%
31%
31%
21%
21%
24
22
20
18
16
12
12
13
12
13
9
8
7
10
6
1.9%
31%
31%
14
5
18
0.3
5
5
2
4
m
sr
sL
sR
p
3
Consensus values (corrected)
Z-scores for Dimethyl sulphide
Reference values
y ref
14.92
U ref (k=2)
0.49
4
3
2
1
0
-1
-2
-3
Laboratory Code
9
8
7
6
5
4
-4
3
Standard deviation for
evaluation
ˆ
0.45
CV
3.0%
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 75 of 78
Methyl mercaptane
(µmol/mol)
Reported data
lab
value
std. dev. U (k=2)
1
2
3
18.1
0.14
1.8
4
21.99
0.16
0.33
5
6
7
16.3
0.19
1.4
8
9
12
20.8
0.5
2.8
13
flag
n
0
0
2
7
0
0
3
0
0
2
0
20.0
0.22
2.9
2.9
4
19.4
1.9
2.1
Z
En
-0.75
0.76
1.85
9.40
0.51
7.70
-1.46
-1.71
-0.59
0.29
7.04
1.26
Results for Methyl mercaptane
Consensus values (raw)
m
sr
sL
sR
p
Median
MAD
AAD
Z raw
1.1%
14%
14%
24
22
20
10%
11%
18
16
12
9
12
13
9
12
13
8
7
6
5
10
4
1.1%
14%
14%
14
3
20.0
0.22
2.9
2.9
4
2
m
sr
sL
sR
p
1
Consensus values (corrected)
Z-scores for Methyl mercaptane
Reference values
y ref
17.15
U ref (k=2)
0.53
4
3
2
1
0
-1
-2
-3
Laboratory Code
8
7
6
5
4
3
2
-4
1
Standard deviation for
evaluation
ˆ
0.51
CV
3.0%
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 76 of 78
Ethyl mercaptane
(µmol/mol)
Reported data
lab
value
std. dev. U (k=2)
1
2
3
4
34.42
0.23
0.47
5
6
7
25.7
0.32
2.3
8
9
12
42.1
0.7
1.9
13
flag
n
0
0
0
7
0
0
3
0
0
2
0
34
0.34
7
7
3
34
8
6
Z
En
0.11
7.93
6.55
-0.95
-2.50
-0.83
1.05
17.12
6.89
Results for Ethyl mercaptane
Consensus values (raw)
m
sr
sL
sR
p
Median
MAD
AAD
Z raw
1.0%
21%
21%
45
23%
17%
35
40
30
Consensus values (corrected)
25
9
12
13
9
12
13
8
7
6
5
4
20
3
1.0%
21%
21%
2
34
0.34
7
7
3
1
m
sr
sL
sR
p
Z-scores for Ethyl mercaptane
Reference values
y ref
27.8
U ref (k=2)
0.9
4
3
2
1
0
-1
-2
-3
Laboratory Code
8
7
6
5
4
3
2
-4
1
Standard deviation for
evaluation
ˆ
0.83
CV
3.0%
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 77 of 78
Carbonyl sulphide
(µmol/mol)
Reported data
lab
value
std. dev. U (k=2)
1
2
3
16.7
0.14
1.7
4
15.85
0.13
0.31
5
6
7
14.8
0.04
2.0
8
9
12
22.8
0.7
3.0
13
flag
n
0
0
2
7
0
0
3
0
0
2
0
16.7
0.24
3.1
3.1
4
16.3
1.4
2.2
Z
En
-0.01
-0.25
3.68
1.79
0.90
1.02
-0.55
-0.61
-0.13
1.68
17.18
2.49
Results for Carbonyl sulphide
Consensus values (raw)
m
sr
sL
sR
p
Median
MAD
AAD
Z raw
1.4%
19%
19%
24
22
20
9%
14%
18
16
12
9
12
13
9
12
13
8
7
6
5
10
4
1.4%
19%
19%
14
3
16.7
0.24
3.1
3.1
4
2
m
sr
sL
sR
p
1
Consensus values (corrected)
Z-scores for Carbonyl sulphide
Reference values
y ref
15.04
U ref (k=2)
0.72
4
3
2
1
0
-1
-2
-3
Laboratory Code
8
7
6
5
4
3
2
-4
1
Standard deviation for
evaluation
ˆ
0.45
CV
3.0%
Annex D: Laboratory results and evaluationAnnex C: Procedure for statistical analysis and evaluation of
laboratory results
Page 78 of 78
Total sulphur
(µmol/mol)
Reported data
lab
value
std. dev. U (k=2)
1
2
3
4
5
6
7
107.4
0.90
4.4
8
9
12
172.9
3.74
11.9
13
flag
n
0
0
0
0
0
0
3
0
0
2
0
1.7%
35%
35%
-0.56
-0.61
0.85
11.29
5.14
170
23%
23%
150
140
130
120
110
13
12
9
8
7
6
5
4
100
3
1.7%
35%
35%
2
134
2.3
46
46
2
-0.57
160
Consensus values (corrected)
m
sr
sL
sR
p
En
180
1
134
2.3
46
46
2
140
33
33
Z
Results for Total sulphur
Consensus values (raw)
m
sr
sL
sR
p
Median
MAD
AAD
Z raw
Z-scores for Total sulphur
Reference values
y ref
110.5
U ref (k=2)
2.6
4
3
2
1
0
-1
-2
-3
Laboratory Code
13
12
9
8
7
6
5
4
3
2
-4
1
Standard deviation for
evaluation
ˆ
5.5
CV
5.0%