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CENTRO DE METROLOGIA QUIMICA. CALCULATION OF UNCERTAINTIES FOR THE REPORT OF ANALYSES IN SIM.8.P1.2 (C HLORINATED P ESTICIDES IN H EXANE ). HEXACHLOROBENZENE gamma-HCH (g-BHC, LINDANE) HEPTACHLOR HEPTACHLOR EPOXIDE 2,4'-DDE CIS-CHLORDANE (ALPHA-CHLORDANE) TRANS-NONACHLOR DIELDRIN - PowerPoint PPT Presentation
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1
CENTRO DE METROLOGIA QUIMICA
CALCULATION
OF
UNCERTAINTIES
FOR THE REPORT OF
ANALYSES
IN SIM.8.P1.2
(CHLORINATED PESTICIDES IN
HEXANE)
3
ANALYTICAL MEASUREMENT
• HEXACHLOROBENZENE
• gamma-HCH (g-BHC, LINDANE)
• HEPTACHLOR
• HEPTACHLOR EPOXIDE
• 2,4'-DDE
• CIS-CHLORDANE (ALPHA-CHLORDANE)
• TRANS-NONACHLOR
• DIELDRIN
• 4,4'-DDE
• 2,4'-DDD
• 2,4'-DDT
• 4,4'-DDT
• MIREX
Gas ChromatographPerkin-Elmer Model 8000 series 2 with Electron Capture Detector and manual injector
Column Phase, BP- 5 Col. Length, 50.00 mCol. i.d., 0.33 mm
Col. film thickness, 0.50 µm
4
ANALYTICAL MEASUREMENT
• NIST-SRM 2261 was used for the preparation of calibration standards.
• The quantification method used was bracketing using the method of internal standard.
• Sample of SIM.QM-P1 was selected as control
5
ANALYTICAL MEASUREMENT
GENERAL SCHEME OF ANALYTICAL MEASUREMENT
Gravimetric Preparation of standards, samples and
controls
Gravimetric Preparation of dilution
Verification of the standards through the calibration curve
Determination by bracketing using the method of internal standard
Statistical evaluation of the results and uncertainty calculation
6
GRAVIMETRIC PREPARATION OF STANDARDS
A m p o u le s S M R 2 2 6 1
s o l. IN T 1 s o l . IN T 3
S ta n d a rd B ra c k lo w
S ta n d a rd
B ra c k h ig h
IS – s o l. IN T
IS s o l id
7
BRACKETING SCHEME
120
58
40
20
8
4,4 ‘ -DDE
HCB, g-HCH, HEPTACLOR EPOXI, MIREX, 2’4-DDT, 4’4-DDT
DIELDRIN
HEPTACLOR (s/d), cis-CLORDANO, trans-
NONACLOR, 2’4-DDD, 2’4-DDE
ng/g
8
THE UNCERTAINTY ESTIMATION PROCESS
SPECIFY MODEL ASSOCIATED TO THEMEASUREMENT
IDENTIFY UNCERTAINTY SOURCES
QUANTIFY UNCERTAINTY COMPONENTS
CONVERT TO STANDARD UNCERTAINTY
CALCULATE THE COMBINED UNCERTAINTY
OBTAIN EXPANDED UNCERTAINTY
9
BRACKETING AND INTERNAL STANDARD
(AL/AIS)
(AH/AIS)
CL/CISCH/CIS
(AS/AIS)
CS/CIS
Sample concentration is calculated trough the equation:
SIClowstdC
SIAlowstdA
SIA
highstdA
SIAlowstdA
SIA
sampleA
SIClowstdC
SIC
highstdC
SIC
sampleC.
..
.*
..
SIAlow
A
SIA
sampleA
SIClow
C
SIC
sampleC
SIAlowA
SIA
highA
SIClowC
SIC
highC
10
Csample
IDENTYFYING UNCERTAINTY SOURCES
m
Cal. balance
Cal.weightsRep.
Cstd
SMR
m
Cal. balanceCal.weights
Rep.
CIS
purity
Rep.
AREA S,STD,ISf d
Rep.
Cal. weights
Cal. balance
11
Csample
QUANTIFYING UNCERTAINTY SOURCES
m
Cal. balance
Cal.weightsRep.
Cstd
SMR
12
UNCERTAINTY OF THE STANDARDS
2
concent
2
sol
solw
2
std
stdw
concent
u
w
u
w
uCuC
2
weights
2
rep
2
balanceweights uu2uu
solutionweight
stdConcstdweightC std.
13
UNCERTAINTY OF THE STANDARDS
balancetheof nCalibratio
weightingtheityrepeatibil
weightsthencalibratio
2
weights
2
rep
2
balanceweights uu2uu
2
conc
cu2
solw
solwu2
stdw
stdwuCcu
..
14
solutionweight
standardConcstdweightC gug
..)/
3
Uu valuecertC
.
15
0.6%
GRAVIMETRIC PREPARATION OF STANDARDSAmpoules SMR 2261
sol. INT 1 sol. INT 3
StandardBrack low
StandardBrack high
IS – sol. INT
IS solid
0.5%
0.6%
0.6%
0.6%
16
Csample
IDENTYFYING UNCERTAINTY SOURCES
m
Cal. balance
Cal.weightsRep.
Cstd
SMR
m
Cal. balanceCal.weights
Rep.
CIS
purity
17
Csample
IDENTYFYING UNCERTAINTY SOURCES
CIS
Purity m
Cal. balanceCal.weights
Rep.
m
Cal. balance
Cal.weightsRep.
Cstd
SMR
18
PURITY OF THE INTERNAL STANDARD
The purity of IS is quoted by the supplier as 99.0 % . The quoted uncertainty is taken as a rectangular distribution
19
Rep.
AREA S,STD,IS
QUANTIFYING UNCERTAINTY SOURCES
Csample
m
Cal. balance
Cal.weightsRep.
Cstd
SMR
m
Cal. balanceCal.weights
Rep.
CIS
purity
20
The uncertainties associated with the variability of the area were estimated by making replicate measurements of samples and bracketing standards. These uncertainties are estimated through the following equation:
n
reparea
su
UNCERTAINTY STANDARD OF THE SIGNAL
21
UNCERTAINTY STANDARD OF THE SIGNAL
L o w s t d H i g h s t d S a m p l e
H C B A s t d A I S A s t d A I S A A I S
A m p . 1 1 5 , 9 8 1 7 , 0 5 4 4 , 9 2 1 7 , 7 8 2 2 , 7 2 1 6 , 6 3
A m p . 2 1 6 , 9 1 1 7 , 8 3 4 3 , 7 2 1 7 , 5 8 2 1 , 5 9 1 5 , 4 4
A m p . 3 1 5 , 1 7 1 6 , 5 0 4 8 , 1 0 1 8 , 6 6 1 9 , 2 4 1 3 , 9 6
H C B A l o w / A I S A h i g h / A I S A s a m p l e / A I S
A m p . 1 0 , 9 4 2 , 5 2 1 , 3 7
A m p . 2 0 , 9 5 2 , 4 9 1 , 4 0
A m p . 3 0 , 9 2 2 , 5 8 1 , 3 8
a v e r a g e 0 , 9 3 2 , 5 3 1 , 3 8S t a n d a r d d e v i a t i o n 0 , 0 1 0 , 0 5 0 , 0 2
u s t a n d a r d 0 , 0 0 8 0 , 0 2 7 0 , 0 2 7
22
QUANTIFYING UNCERTAINTY SOURCES
Csample
m
Cal. balance
Cal.weightsRep.
Cstd
SMR
m
Cal. balanceCal.weights
Rep.
CIS
purity
Rep.
AREA S,STD,IS
dilution factor
Rep.
Cal. weights
Cal. balance
23
CALCULATING THE CONCENTRATION
HCB Value (x)Standard uncertainty
u(x)
C low 20.71 0.059
C high 57.97 0.160
C IS (low ) 129.7 0.959
C IS (high ) 129.5 0.958
C IS (sample) 132.1 0.983
Dilution factor 1.10 0.00012
A low / A IS 0.93 0.008
A high / A IS 2.53 0.027
A sample/ A IS 1.38 0.027
24
HCB: COMBINED UNCERTAINTYHCB A sample/ A low / A high / C low C high C IS low C IS high C IS fd
A IS A IS A IS samplevalue 1,38 0,93 2,53 20,71 57,97 129,70 129,5 132,1 1,10
uncertainty 0,009 0,008 0,027 0,059 0,160 0,96 0,96 0,98 0,00012
A sample/ A IS 1,38 1,39 1,38 1,38 1,38 1,38 1,38 1,38 1,38 1,38
A low / A IS 0,93 0,93 0,94 0,93 0,93 0,93 0,93 0,93 0,93 0,93
A high / A IS 2,53 2,53 2,53 2,56 2,53 2,53 2,53 2,53 2,53 2,53
C low 20,71 20,71 20,71 20,71 20,77 20,71 20,71 20,71 20,71 20,71
C high 57,97 57,97 57,97 57,97 57,97 58,13 57,97 57,97 57,97 57,97
C IS (low ) 129,7 129,70 129,70 129,70 129,70 129,70 130,66 129,70 129,70 129,70
C IS (high ) 129,5 129,49 129,49 129,49 129,49 129,49 129,49 130,45 129,49 129,49
C IS (sample) 132,1 132,15 132,15 132,15 132,15 132,15 132,15 132,15 133,13 132,15
fd 1,10 1,10 1,10 1,10 1,10 1,10 1,10 1,10 1,10 1,10
C sample 34,9 35,16 34,76 34,73 34,97 34,97 34,80 34,79 35,18 34,93
0,23 -0,16 -0,19 0,05 0,05 -0,12 -0,13 0,26 0,00
0,22 0,05 0,03 0,04 0,00 0,00 0,02 0,02 0,07 0,00
uncertainty(u) 0,47 49% 34% 41% 10% 11% 26% 28% 55% 1%
Incert. Exp. (U) 0,94RU (%) 2,70
25
UNCERTAINTY CONTRIBUTIONS
Uncertainties in Determination of HCB
0,00 0,05 0,10 0,15 0,20 0,25 0,30 0,35 0,40 0,45 0,50
A sample/ A IS
A low / A IS
A high / A IS
C low
C high
C IS (low )
C IS (high )
C IS (sample)
C sample
u (y,xi)
26
CONCENTRATION AND UNCERTAINTY VALUES FOR THE SAMPLE SIM.8.P1.2
Meanng/g
Ung/g
RU%
Hexachlorobenzene 34.9 0.9 3gamma-HCH(g-BHC,lindane)
25.1 1.5 6
Heptachlor 17.2 1.6 9
Heptachlor epoxide 45.0 1.5 3
2,4'-DDE 53.8 4.2 8cis-Chlordane(alpha-chlordane)
85.6 3.0 3
trans-Nonachlor 75.3 4.4 6
Dieldrin 139 7.3 5
4,4'-DDE 513 28.9 6
2,4'-DDD 73.7 4.8 6
2,4'-DDT 25.4 1.2 5
4,4'-DDT 44.4 2.1 5
Mirex 26.7 0.7 3