Upload
vantruc
View
224
Download
3
Embed Size (px)
Citation preview
1
CCQM-K11.1: Subsequent Key Comparison on the Determination of
Glucose in Serum
Final Report
September 2006
Lian Hua Shi, Byung-Joo Kim, Hwa-Shim Lee, and Sang-Ryoul Park
Korea Research Institute of Standards and Science (KRISS)
Daejeon, Korea
Marco Antonio Avila Calderón and Melina Pérez Urquiza
Centro Nacional de Metrología (CENAM)
Querétaro, México
Hisashi Kato
National Metrology Institute of Japan (NMIJ)
Tsukuba, Japan
Can Quan and Hongmei Li
National Research Center for Certified Reference Materials (NRCCRM)
Beijing, China
INTRODUCTION
The accuracy and traceability of routine clinical diagnostic tests has become a matter of
great concern. Inconsistency in test results due to the lack of high quality measurement
standards implemented in clinical practices often leads to confusion in making medical
decisions as well as unnecessary and costly repeats of tests. This problem has been
legally addressed by the European Union to implement of an In-vitro Diagnostic (IVD)
Directive. Other parts of the world are likely to follow the EU in requiring greater
traceability for IVD products. Upon this change, CIPM, IFCC, and several other related
international organizations have organized the Joint Committee on Traceability in
Laboratory Medicine (JCTM) to help implementation of measurement standards in the
2
field of laboratory medicine [1]. National metrology institutes (NMIs) are to take great
responsibility in development and dissemination of measurement standards of higher
order. Therefore, Key Comparisons of substances of great diagnostic values have been
actively organized and carried out under CCQM.
Glucose is one of the most frequently measured substances in human blood. Although
various measurement methods have been established and applied, the accuracy of the
clinical tests is still of great concern. Therefore, providing measurement standards based
on a primary reference method is an important matter. In 2002, Organic Analysis
Working Group (OAWG) of CCQM had performed a key comparison of determination
of glucose in human serum in which three NMIs (NIST, KRISS, PTB) had participated
and demonstrated their capability for determination of glucose in human serum. The
results of the KC are available from the BIPM KCDB [2].
There were other NMIs who needed to demonstrate their measurement capabilities in
determination of glucose in human serum in a form of CCQM Key Comparison.
Considering the situation, the chair of OAWG arranged a Subsequent Key Comparison
(CCQM-K11.1). Under the guidance of OAWG, KRISS who demonstrated its
measurement capability in CCQM-K11 coordinated the Subsequent Key Comparison.
CENAM (Mexico), NMIJ (Japan), NRCCRM (China), and VNIM (Russia) participated
in the Subsequent Key Comparison, and two sets of test materials representing normal
and elevated glucose levels in human serum were sent. All participants except VNIM
successfully returned measurement results. Returned data were presented in OAWG
Fall meeting of 2005 with minimum data processing, and no significant comments on
the results of the Subsequent Key Comparison were made by OAWG. In the final report,
modifications of initially reported expanded uncertainties were made as NRCCRM and
KRISS found needs for correction in their assessments. As not allowed, no modification
was made in the initially reported mean values.
The draft of the final report was submitted to the 2006 April meeting of OAWG,
OAWG decided to place the originally reported expanded uncertainties by participants
as the final values. This recommendation has been reflected in the revised report.
Corrections of some miscalculations in the previous draft repro were also made.
3
SUMMARY OF ORIGINAL CCQM-K11 STUDY
A Key Comparison on the determination of glucose in human serum, CCQM-K11 was
conducted in 2002 with National Institute of Standards and Technology (NIST) as the
coordinating laboratory. Two laboratories participated in this Key Comparison:
Country Institution
Korea Korea Research Institute of Standards and Science, KRISS
Germany Physikalisch-Technische Bundesanstalt, PTB
USA National Institute of Standards and Technology, NIST (Pilot Lab)
The details of the study outcome can be found at the BIPM website [2]. The conclusion
of the study was that the participating NMIs demonstrated the ability to make accurate
and precise measurements of glucose in human serum with the exception of Material II
of the KC. The essential part of the results of this study is presented in Table 1.
CONDUCT OF THIS STUDY (CCQM-K11.1; CCQM-K11-Subsequent)
Participants
The following five countries participated in this study:
Country Institution
China National Research Centre for Certified Reference Materials, NRCCRM
Japan National Metrology Institute of Japan, NMIJ
Korea KRISS (Coordinating Laboratory)
Mexico National Center of Metrology, CENAM
Russia D.I. Mendeleyev Institute for Metrology, VNIM (data not returned)
VNIM had received test materials, but could not perform measurements due to the lack
of resources. KRISS is the only laboratory participated in CCQM-K11 and had
demonstrated capability for accurate measurement of glucose in human serum.
Therefore, KRISS, the coordinating laboratory was to provide a link to CCQM-K11 for
the results of this study.
4
Methods Used for the CCQM-K11-Subsequent Comparison
VNIM unfortunately could not perform measurement at this time due to the lack of
resources. The laboratories chose to use either GC/ID-MS or LC/ID-MS. KRISS used
ultra-filtration with 3000 Da cut-off filters for removal of proteins. Other laboratories
used ethanol precipitation. Three laboratories used NIST SRM917b as the high purity
glucose for preparation of standard solutions. NRCCRM used a product from Amresco
Inc. of which purity was claimed to be 99.8 %. CENAM and KRISS performed
validation of the measurements with CRM DMR-263a and NIST SRM 965a, respectively.
Table below is the summary of the methods used by each laboratory.
Laboratory Sample prep. &
derivatization
Measurement Calibration
material
Validation
CENAM Ethanol precip. &
NH4OH derive.
GC/ID-MS NIST SRM917b CRM DMR-
263a
KRISS Ultra-filtration
(3000 Da)
LC/ID-MS NIST SRM 917b NIST SRM 965a
NMIJ Ethanol. percip.
LC/ID-MS NIST SRM 917b
NRCCRM Ethanol precip. &
NH4OH derive.
GC/ID-MS Amresco*,
99.8%
VNIM Not ready to perform
analysis
NA NA NA
* The Amresco Inc. product was supplied without uncertainty certification.
Materials Used for the CCQM-K11-Subsequent Comparison
Candidate certified reference materials of human serum prepared by KRISS were used
as test materials in this study. The test materials were natural human serum to which no
preservative was added. Only antiseptic filtering and/or fortification were applied.
Homogeneity of glucose levels was estimated 0.4 % RSD for both test materials as
presented in the figure below.
5
Target ranges were given as follows:
01A 02A
Glucose 1100 – 1400 mg/kg 600 – 900 mg/kg
0 2 4 6 8 10
0.96
0.98
1.00
1.02
1.04
De
via
tio
n
Vial number
0 2 4 6 8 10
0.96
0.98
1.00
1.02
1.04
De
via
tio
n
Vial number
01A 02A
Results of homogeneity test of the test materials for glucose measurement.
The test materials were to be kept frozen (either at -20 oC or at -70
oC ). However, no
visible sign of degradation was observed during storage at room temperature for several
weeks as far as the seals were intact. Each test material consisted of 4 vials of 3 mL of
human serum. For the set of 4 vials, one is for practice and/or for better determining the
target concentration whereas the rest 3 vials are for measurement. The test materials
were sent as packed with a sufficient amount of dry ice to keep them frozen for several
days. However, test materials sent to VNIM and to NRCCRM were exposed to ambient
temperature for more than 10 days because of trouble at custom offices. KRISS
performed measurements with test materials exposed to room temperature for 20 days
and found no significant difference from the measurement results with normally stored
materials. Based on this result, NRCCRM performed the measurements without
replacement of originally received test materials.
Extra care needed to be taken to avoid microbial consumption of glucose as soon as the
test materials are exposed to ambient air. Immediate spiking of an appropriate antibiotic
agent was recommended.
6
Measurement Protocol and Calculation of Uncertainty
As requested, all participants except VNIM produced two independent results from each
vial of a test material. Three vials of a test material were distributed. Therefore, 6
measurements were resulted from each test material. The results were to be reported on
an absolute basis (corrected for chemical purity of the calibration material used by the
participant) together with the expanded uncertainty. Space was provided at the end of
the data reporting sheets for inclusion of a full uncertainty budget, including definition
of terms and assessment of which components made significant contributions.
Linking the Subsequent Key Comparison to the Original Key Comparison
The results of CCQM-K11-Subsequent were initially treated as if an independent Key
Comparison was carried out (Table 2-1 & 2-2). Then, liking them to the results of the
original Key Comparison was made by applying proportionality factors obtained
through comparison of KRISS results from both Key Comparisons. KRISS results from
the Subsequent Key Comparison were assumed to have the same fractions of deviation
from KCRVs (virtual values) as determined in the original Key Comparison. From this
assumption, KCRVs of the Subsequent Comparison were assigned as noted as assigned
KCRVs in Table 3. One problem was that KCRV was not determined for the elevated
level of glucose (Material II). Considering the closeness of glucose concentrations in
two test materials, assigned KCRV for Test Material 01A was also calculated by
comparing the results to those for Material I of CCQM-K11. Calculation of the assigned
KCRVs is shown bellow.
Assignment of the KCRV for Test Material 01A of K11.1:
Assigned KCRV = 1248.7 mg/kg x (776.2/775.3) = 1250.1 mg/kg
776.2 mg/kg: KCRV for Material I of CCQM-K11;
775.3 mg/kg: KRISS result for Material I of CCQM-K11;
1248.7 mg/kg: KRISS result for Test Material 01A of CCQM-K11.1
Assignment of the KCRV for Test Material 02A of CCQM-K11.1:
Assigned KCRV = 779.90 mg/kg x (776.2/775.3) = 780.81 mg/kg
776.2 mg/kg: KCRV for Material I of CCQM-K11;
775.3 mg/kg: KRISS result for Material I of CCQM-K11;
779.9 mg/kg: KRISS result for Test Material 02A of CCQM-K11.1
7
Originally, expanded uncertainties were also linked to the results of original Key
Comparison in the same manner as applied for calculation of deviations of from KCRVs.
Calculation of adjusted uncertainties are shown below.
Adjustment of expanded uncertainties for Test Material 01A
Adjusted Uncertainties = Reported uncertainties x (1.41/0.897)
1.41 %: KRISS Rel. Uncertainty (%) for Material I of CCQM-K11;
0.897 %: KRISS Rel. Uncertainty (%) for Test Material 01A of CCQ-K11.1
Adjustment of expanded uncertainties for Test Material 02A
Adjusted Uncertainties = Reported uncertainties x (1.41/0.907)
1.41 %: KRISS Rel. Uncertainty (%) for Material I of CCQM-K11;
0.907 %: KRISS Rel. Uncertainty (%) for Test Material 02A of CCQ-K11.1
During the CCQM meeting in April 2006, Organic Analysis Working Group decided to
accept the originally reported expanded uncertainty by each participating laboratory as
the final values of the expanded uncertainty. Therefore, the values calculated above for
linking to the original study were not taken as the final values.
RESULTS
Results for the CCQM-11-Subsequent Comparison are summarized in Table 2. The
uncertainty bars in the figures represent expanded uncertainties as reported by the
participating laboratories. Uncertainties in the results of NRCCRM were changed from
the values reported in OAWG fall meeting 2005 as requested by NRCCRM. KRISS
also refined its uncertainty budgeting procedure and made minor modifications of
originally reported uncertainties. Evaluation of uncertainty reported by each laboratory
is summarized in Table 5. The results of linking the results of this Subsequent Key
Comparison to the original Key Comparison are presented in Table 3. As decided by
OAWG, the uncertainties originally reported by participants were placed as the final
values regardless the results of linking to the results of CCQM K-11.
DISCUSSION
KRISS is the only laboratory participated in the original CCQM-K11 Key Comparison
[2]. KRISS, the coordinating laboratory, is to provide a link to the results of the original
Key Comparison for the results of this Subsequent Key Comparison. KRISS proved its
8
capability for accurate measurement of glucose in human serum in the original Key
Comparison study. In addition, KRISS validated its measurement procedure by
performing simultaneous measurement of NIST SRM 965A as shown below.
1193.58 ± 21.56KRISS measurement
1192.97 ± 12.7122.1 ± 1.3Certified value
mg/kgmg/dLLevel 3
769.44 ± 15.35KRISS measurement
766.60 ± 8.3978.50 ± 0.86Certified value
mg/kgmg/dLLevel 2
NIST SRM 965a
(frozen serum)
1193.58 ± 21.56KRISS measurement
1192.97 ± 12.7122.1 ± 1.3Certified value
mg/kgmg/dLLevel 3
769.44 ± 15.35KRISS measurement
766.60 ± 8.3978.50 ± 0.86Certified value
mg/kgmg/dLLevel 2
NIST SRM 965a
(frozen serum)
It was unfortunate that VNIM could not perform measurements because of insufficient
resources for the moment. CENAM’s results showed good agreement with KRISS
results for both test materials. It might not be a pure coincidence that both laboratories
validated their measurement procedures using reference materials. NRCCRM’s result
showed a good agreement with the results of CENAM and KRISS for Test Material
01A but produced significantly lower mean value with a relatively larger uncertainty for
Test Material 02A. NMIJ reported substantially higher mean values for both test
materials with substantially larger uncertainties (Table 2).
Homogeneity of test materials should not be a major factor for scattering of the data
(especially NMIJ’s results) because the results of measurement of three vials were
relatively close to each other (0.2-0.5 % RSD) in the results of CENAM, KRISS, and
NRCCRM (see Figure below). The vials were randomly chosen from the pools of
several thousand vials. Substantial scattering of NMIJ’s data for Test Material 02A
(1.6% RSD) is also noticeable. NMIJ may need to validate the measurement procedure
applied to this study.
9
1200
1250
1300
1350
1400
Glu
co
se
(m
g/k
g)
760
780
800
820
840
860
Glu
co
se
(m
g/k
g)
CE
NA
M
KR
ISS
NM
IJ
NR
CC
RM
CE
NA
M
KR
ISS
NM
IJ
NR
CC
RM
Test Material 01A Test Material 02A
1200
1250
1300
1350
1400
Glu
co
se
(m
g/k
g)
760
780
800
820
840
860
Glu
co
se
(m
g/k
g)
1200
1250
1300
1350
1400
Glu
co
se
(m
g/k
g)
760
780
800
820
840
860
Glu
co
se
(m
g/k
g)
CE
NA
M
KR
ISS
NM
IJ
NR
CC
RM
CE
NA
M
KR
ISS
NM
IJ
NR
CC
RM
Test Material 01A Test Material 02A
NRCCRM’s mean value for Test Material 02A is substantially deviated from the result
of KRISS. With the help of the relatively large expanded uncertainty, however,
NRCCRM’s result was in agreement with the results of CENAM and KRISS. It may
still be a serious matter that NRCCRM used a high purity standard material without
certification of uncertainty.
After conversion of the reported values of this study to get linked to the original Key
Comparison study, % deviations of CENAM, NMIJ, and NRCCRM’s results from the
assigned KCRV of Test Material 01A were 1.1 %, 9.6 %, 0.85 %, respectively. NMIJ ‘s
result was absolutely deviated. Other two labs’ results were also relatively largely
deviated compared to the maximum deviation of 0.5 % of CCQM-K11. However, these
results were in agreement within the expanded uncertainties. The relative expanded
uncertainty of CENAM’s measurement was comparable to that of PTB’s result of
CCQM-K11 (1.4 % vs. 1.4 %). The relative expanded uncertainty of NRCCRM’s
measurement is significantly larger (2.3 %).
10
CONCLUSIONS
In this study, CCQM-11.1 Key Comparison, CENAM and NRCCRM demonstrated
their ability in measurement of glucose in human serum at both clinically normal level
and elevated level in. The degrees of equivalence demonstrated in this study (%U: 2.8 –
6.9 %) were significantly inferior to that of the original Key Comparison (%U: 1.13 %).
Inclusion of NRCCRM data for Test Material 02A needs to be discussed by OAWG.
Exposure to ambient temperature for an extended time period (~ 2 weeks) might
partially contribute to the substantially underestimating result of NRCCRM. Regardless,
NRCCRM seems to need to improve the measurement uncertainty to the level that other
NMIs showed in CCQM-K11 and its subsequent comparison. In addition, NRCCRM
has to establish an uncertainty in determination of the purity of its high purity standard
material or to use a material provided with certification of uncertainty to have
appropriate measurement traceability to SI unit. NMIJ reported substantially elevated
results for both test materials. NMIJ needs to find the sources of the substantial bias and
validate its measurement procedure using a reliable reference material.
REFERENCES
[1] http://www.bipm.org/en/committees/jc/jctlm/
[2] http://www.bipm.org/utils/common/pdf/final_reports/QM/K11/CCQM-K11.pdf.
11
Table 1-1. Results of CCQM-K11 Glucose in Human Serum: Material I
Units: mg/kg
Participant Mean Standard U
ncertainty
Degrees of
freedom
k Expanded
uncertainty
KRISS 775.3 3.4 2.9 3.180 10.9
NIST 780.1 4.1 357 1.967 8.1
PTB 773.2 2.5 2 4.303 10.8
Mean: 776.2
Std dev of mean: 2.04
Degrees of Freedom: 2
K factor: 4.303
U: 8.8
U(rel) %: 1.1%
KCRV: 776.2 mg/kg 8.8 mg/kg
(treated as an independent study)
Table 1-2. Results of CCQM-K11 Glucose in Human Serum: Material II
Units: mg/kg
Participant Mean Standard U
ncertainty
Degrees of
freedom
k Expanded
uncertainty
KRISS 1455.9 24.90
NIST 1474.4 15.32
PTB 1514.6 18.18
Mean: 1494.5
Std dev of mean: 16.41
Degrees of Freedom: 2
K factor: 4.303
U: 70.6
U(rel) %: 4.72%
KCRV Undetermined
12
Table 2-1. Results of CCQM-K11.1 Glucose in Human Serum: Test
Material 01A
Units: mg/kg
Participant Mean Standard
Uncertainty
Degrees of
freedom
k Expended
uncertainty
CENAM 1264 8.3 13* 2.16 18
KRISS 1249 5.5 31 2.04 11
NMIJ 1370 8.0 35* 2.03 16
NRCCRM 1261 15 1000* 1.96 29
VNIM N/A N/A N/A N/A N/A * The unreported degrees of freedom were assigned by the coordinating lab based on the reported k value.
NMIJ data were excluded in the following calculations.
Mean: 1258
Std dev of mean: 8.2
Degrees of Freedom: 2
K factor: 4.30 (95% confidence level)
U: 35
Relative U (%): 2.8
KCRV 1258 mg/kg 35 mg/kg
(treated as an independent study)
1200
1250
1300
1350
1400
Glu
co
se (
mg
/kg
)
CE
NA
M
KR
ISS
NM
IJ
NR
CC
RM
13
Table 2-2. Results of CCQM-K11.1 Glucose in Human Serum: Test
Material 02A
Units: mg/kg
Participant Mean Standard
Uncertainty
Degrees of
freedom
k Expanded
uncertainty
CENAM 786.1 4.3 13* 2.31 9.6
KRISS 779.9 3.5 31 2.04 7.1
NMIJ 834.5 11 35* 2.03 23
NRCCRM 762.1 9.2 1000* 1.96 18
VNIM N/A N/A N/A N/A N/A * The unreported degrees of freedom were assigned by the coordinating lab based on the reported k value.
NMIJ data were excluded in the following calculations.
Mean: 776
Std dev of mean: 12.5
Degrees of Freedom: 2
K factor: 4.30 (95% confidence level)
U: 54
Relative U (%): 6.9
KCRV 776 mg/kg 54 mg/kg
(treated as an independent study)
CE
NA
M
KR
ISS
NM
IJ
NR
CC
RM
720
740
760
780
800
820
840
860
Glu
co
se
(m
g/k
g)
CE
NA
M
KR
ISS
NM
IJ
NR
CC
RM
720
740
760
780
800
820
840
860
Glu
co
se
(m
g/k
g)
14
Table 3-1. Link to the original study: Test Material 01A (elevated glucose
level)
Units: mg/kg; Linked KCRV = 1250.1 (See page 6)
Participant Mean of
K11.1
Difference
from
KCRV
% Difference
from KCRV
% Rel.
uncertainty, K11.1
(Linked to K11)***
Finalized
rel.
uncertainty
(%)
CENAM 1264 14 1.1 1.4 (2.2) 1.4
KRISS 1248.7 -1.4 -0.11 0.90 (1.4) 0.90
NMIJ 1369.5 120 9.6 1.3 (1.9) 1.3
NRCCRM 1261 11 0.85 2.3 (3.7) 2.3
NIST 0.50* 1.0
**
PTB -0.39* 1.4
**
* % difference in CCQM-K11;
** relative expanded uncertainty in CCQM-K11;
*** % relative uncertainty
calculated as linked to the results of CCQM-K11 assuming the uncertainty of KRISS was exactly
maintained.
-4
-2
0
2
4
6
8
10
12
% D
iffer
ence
from
KC
RV
CE
NA
M
KR
ISS
NM
IJ
NR
CC
RM
KR
ISS
NIS
T
PT
B
K-11 K-11.1
-4
-2
0
2
4
6
8
10
12
% D
iffer
ence
from
KC
RV
CE
NA
M
KR
ISS
NM
IJ
NR
CC
RM
KR
ISS
NIS
T
PT
B
K-11 K-11.1
15
Table 3-2. Link to original study: Test Material 02A (normal glucose level)
Units: mg/kg; Linked KCRV = 780.81 (See page 6)
Participant Mean of
K11.1
Difference
from
KCRV
% Difference
from KCRV
% Rel.
uncertainty, K11.1
(Linked to K11) ***
Finalized
rel.
uncertainty
(%)
CENAM 786.1 5.3 0.68 1.2 (1.9) 1.2
KRISS 779.9 -0.9 -0.12 0.91 (1.4) 0.91
NMIJ 834.5 53.7 6.9 3.0 (4.3) 3.0
NRCCRM 762.1 -18.7 -2.4 2.3 (3.8) 2.3
NIST 0.50* 1.0
**
PTB -0.39* 1.4
**
* % difference in CCQM-K11;
** relative expanded uncertainty in CCQM-K11;
*** % relative uncertainty
calculated as linked to the results of CCQM-K11 assuming the uncertainty of KRISS was exactly
maintained.
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
% D
iffer
ence
from
KC
RV
CE
NA
M
KR
ISS
NM
IJ
NR
CC
RM
KR
ISS
NIS
T
PT
B
K-11 K-11.1
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
% D
iffer
ence
from
KC
RV
CE
NA
M
KR
ISS
NM
IJ
NR
CC
RM
KR
ISS
NIS
T
PT
B
K-11 K-11.1
16
Table 4-1. Uncertainty Reports: Test Material 01A (CENAM)
Uncertainty Budget (Sources of uncertainty, their type, evaluation and magnitude)
Parameter Source of
uncertainty
xi u(xi)
f
xu x
i
i
( )
Degrees of
freedom
(i)
Type Source of
data
Method
precision
Between batch
precision for the
method as a whole
(major source)
1264,4 6.4 1 5 A
Replicate
analysis of
sample
across two
batches
Calibration
solution
Concentration of
the calibration
solution (corrected
for purity) (major
source)
1254,1 2,5 1 large B Supplier’s
specification
Weight of
sample
Balance linearity
(minor source) 1.00535 0,00016 1 large B
Balance
calibration
certificate
Weight of
calibration
compound
Balance linearity
(minor source) 1,00688 0,00005 1 large B
Balance
calibration
certificate
Sample
response in
GC-MS
Area ratio of
unlabeled/labeled
glucose in sample
(Major source)
1,0234 0,0018 1 3
Repeatibility
of sample
injection
Calibration
solution
response in
GC-MS
Area ratio of
unlabeled/labeled
glucose in
calibration
compound (Major
source)
1,0221 0,0021 1 3
Repeatibility
between
calibration
injection
Other
Other
17
Table 4-2-A. Uncertainty Reports: Test Material 01A (KRISS)
Uncertainty Budget (Sources of uncertainty, their type, evaluation and magnitude)
Parameter Source of
uncertainty
xi u(xi)
f
xu x
i
i
( )
Degrees of
freedom
(i)
Type Source of
data
Method
precision
Between batch
precision for the
method as a
whole (major
source)
1248.7
mg/kg
1.0278
mg/kg
~ 1 5 A Replicate
analysis of
sample
across tree
samples
Calibration
solution
Purity correction
(major source)
99.7% 0.2% ~ 1 large B Certified
value from
SRM
Provider
Weight of cal.
compound
126.58
mg
0.4
mg
~ 1 large B Calibration
certificate
Weight of cal.
solution
19.9021
g
0.4
mg
~ 1 large B Calibration
certificate
Standard
Solution
Accuracy in prep.
of std soln.
0.9965
0.000971
~ 1 3 A Std dev of
R.F. of 4
std solns
u
(Mis_sol,std/Ms_sol,std)
0.94007
0.00069 ~ 1 large B Calibration
certificate
Sample
solution
u
(Mis_sol,std/Ws)
0.56935
0.00011
~ 1 large B Calibration
certificate
Random components were counted in method precision.
ARstd Repeatability
of determination
0.98900
0.00173
~ 1 4 A Replicate
analysis of
std. soln.
ARsample Counted in method precision
18
Table 4-2-B. Uncertainty Reports: Test Material 02A (KRISS)
Uncertainty Budget (Sources of uncertainty, their type, evaluation and magnitude)
Parameter Source of
uncertainty
xi u(xi)
f
xu x
i
i
( )
Degrees of
freedom
(i)
Type Source of
data
Method
precision
Between batch
precision for the
method as a
whole (major
source)
779.90
mg/kg
3.472
mg/kg
~ 1 5 A Replicate
analysis of
sample
across tree
samples
Calibration
solution
Purity correction
(major source)
99.7% 0.2% ~ 1 large B Certified
value from
SRM
Provider
Weight of cal.
compound
126.58
mg
0.4
mg
~ 1 large B Calibration
certificate
Weight of cal.
solution
19.9021
g
0.4
mg
~ 1 large B Calibration
certificate
Standard
Solution
Accuracy in prep.
of std soln.
0.9965
0.000971
~ 1 3 A Std dev of
R.F. of 4
std solns
u
(Mis_sol,std/Ms_sol,std)
0.94007
0.00069 ~ 1 large B Calibration
certificate
Sample
solution
u
(Mis_sol,std/Ws)
0.36348
0.00011
~ 1 large B Calibration
certificate
Random components were counted in method precision.
ARstd Repeatability
of determination
0.98900
0.00173
~ 1 4 A Replicate
analysis of
std. soln.
ARsample Counted in method precision
19
Table 4-3. Uncertainty Reports: Test Material 01A & 02A (NMIJ)
Value Uncertainty, u(xi) degree of freedom Type of uncertainty
Sample preparation
01A 1369.5 4.37 2 A
02A 834.45 5.29 2 A
Vial subdivision
01A 1369.5 4.43 6 A
02A 834.45 6.26 6 A
LC-MS measurement
01A 1369.5 3.16 36 A
02A 834.45 4.00 36 A
Calibration solution purity(NIST SRM-917b) 1)
0.997 0.115 inf B
Weight of sample. 1)
Ws(01A) 0.93305 (g) 0.000016 (g) inf B
Ws(02A) 1.00482 (g) 0.000016 (g) inf B
Weight of the standard compounds taken for preparation of calibration solution. 1)
Wc(917b) 100.61 (mg) 0.016 (mg) inf B
Weight of internal standard solution1)
.
Ws(01A) 15.21 (mg) 0.016 (mg) inf B
Ws(02A) 8.71 (mg) 0.016 (mg) inf B
1) Supposed to be rectangularly distributed.
20
Table 4-4-A. Uncertainty Reports: Test Material 01A (NRCRM)
Uncertainty Budget (Sources of uncertainty, their type, evaluation and magnitude)
Parameter Source of
uncertainty
xi
u(xi)
f
xu x
i
i
( )
Degrees
of
freedom
(i)
Type Source of
data
Method
precision
Between
batch
precision for
the method as
a whole
(major
source)
1260.8mg/kg 1.138mg/kg 1.14mg/kg 5 A
Replicate
analysis of
sample across
two batches
RAS 1.0226
RAL 0.9835
RAH 1.0706
Calibration
solution
Concentration
of the
calibration
solution
(corrected for
purity) (major
source)
1266.5mg/kg 12.69mg/kg 12.9mg/kg large B Supplier’s
specification
Weight of
calibration
compound
Balance
linearity
(minor
source)
1.5593mg 0.05774g 0.0476g large B
Balance
calibration
certificate
Weight of
sample
Balance
linearity
(minor
source)
0.09600g 27.71g 0.372mg/kg large B
Balance
calibration
certificate
21
Table 4-4-B. Uncertainty Reports: Test Material 02A (NRCRM)
Uncertainty Budget (Sources of uncertainty, their type, evaluation and magnitude)
Parameter Source of
uncertainty
xi
u(xi)
f
xu x
i
i
( )
Degrees
of
freedom
(i)
Type Source of
data
Method
precision
Between
batch
precision for
the method as
a whole
(major
source)
762.08mg/kg 0.6738mg/kg 0.674mg/kg 5 A
Replicate
analysis of
sample
across two
batches
RAS 1.0563
RAL 0.9852
RAH 1.0774
Calibration
solution
Concentration
of the
calibration
solution
(corrected for
purity) (major
source)
742.75mg/kg 7.443mg/kg 7.97mg/kg large B Supplier’s
specification
Weight of
calibration
compound
Balance
linearity
(minor
source)
0.8858mg 0.05774g 0.0518mg/kg large B
Balance
calibration
certificate
Weight of
sample
Balance
linearity
(minor
source)
0.09385g 27.09g -0.230mg/kg large B
Balance
calibration
certificate