[Header]
Format=SMU
ver=3
appl=GUMWB32
MR=0
FUEB=0

[Title]
Title='Uncertainty estimation from In-House Validation Studies. Determination of Organophosphorus Pesticides in Bread'
Description=3
Description[0]='This is the example A4 of the EURACHEM / CITAC Guide "Quantifying Uncertainty'
Description[1]='in Analytical Measurement", Second Edition.'
Description[2]=''

[Model]
Model=7
Model[0]='{calculation of the level of pesticide in the sample:'
Model[1]='P_op = (I_op * c_ref * V_op)/(I_ref * Rec * m_sample) * F_hom * 1e6'
Model[2]='but not used to calculate uncertainty}'
Model[3]=''
Model[4]='{calculation of uncertainty}'
Model[5]=''
Model[6]='P_op = P_op\sp\nominal * f_repeatability * f_bias * f_other;'

[Components]
CompOrder=3
Comp=5
Comp[0]=P_op_
Comp[1]=P_op\sp\nominal_
Comp[2]=f_repeatability_
Comp[3]=f_bias_
Comp[4]=f_other_

[COMP 0]
Type=Result
Definition='Level of pesticide in the sample'
Unit='mg/kg'
Description=0
Fcov=2
NomUnit=
UncUnit=
CovID=1
UncID=0
Vnom=1
Ustd=0.33950924398162
Neff=95
HB=1
HC=0
HR=1
IO=0

[COMP 1]
Type=Const
Definition='Nominal level of pesticide in the sample'
Unit='mg/kg'
Description=4
Description[0]='The nominal value of the level of pesticide in the sample is not associated'
Description[1]='with any uncertainty. A value of 1/0.9 is chosen so that P_op will be 1, the'
Description[2]='the combined uncertainty of the result can be used directly as a relative'
Description[3]='uncertainty.'
Vnom==1/0.9

[COMP 2]
Type=TypBNormal
Definition='Uncertainty contribution covering repeatability'
Unit=''
Description=11
Description[0]='Repeatability has been investigated in a precision study. A number of duplicate'
Description[1]='tests (same homogenised sample, complete extraction/determination procedure)'
Description[2]='were performed for typical organophosphorous pesticides found in different'
Description[3]='bread samples (for data see Table A4.2 in the EURACHEM / CITAC Guide). The'
Description[4]='normalised difference data (the difference between the duplicate results'
Description[5]='divided by the mean) provides a measure of the overall run to run variability.'
Description[6]='To obtain the estimated relative standard uncertainty for single'
Description[7]='determinations, the standard deviation of the normalised differences is taken'
Description[8]='and divided by sqrt(2) to correct from a standard deviation for pairwise'
Description[9]='differences to the standard uncertainty for the single values. This gives an'
Description[10]='uncertainty of 0.382/sqrt(2) = 0.27.'
Vnom=1
Uexp==0.382/sqrt(2)
Fcov=1

[COMP 3]
Type=TypBNormal
Definition='Uncertainty contribution due to bias (recovery)'
Unit=''
Description=4
Description[0]='Data from an in-house validation study was used to obtain data on recovery. On'
Description[1]='42 spiked bread samples, the mean recovery was 90% with a standard deviation of'
Description[2]='28%. The standard uncertainty of the recovery is calculated as the standard'
Description[3]='deviation of the mean, 0.28/sqrt(42).'
Vnom=0.9
Uexp==0.28/sqrt(42)
Fcov=1

[COMP 4]
Type=TypBNormal
Definition='Other uncertainty contributions'
Unit=''
Description=25
Description[0]='This factor includes all other sources of uncertainty not adequately covered by'
Description[1]='f_repeatability and f_bias_. Due to the design of the precision study, all'
Description[2]='uncertainty contributions arising from balances and volumetric measurement'
Description[3]='devices are already covered by f_repeatability_. This leaves only the purity of'
Description[4]='the reference standard, the possible nonlinearity of the GC response and the'
Description[5]='sample homogeneity as possible sources of uncertainty. The purity of the'
Description[6]='reference standard is biven by the manufacturer as 99.53% ±0.06%. Assuming a'
Description[7]='rectangular distribution, this would be an additional uncertainty of'
Description[8]='0.0006/sqrt(3) = 0.00035. This uncertaintiy contribution is so small compared'
Description[9]='to e.g. the contribution of f_repeatability, that it can be safely neglected.'
Description[10]='Linearity of the response of the GC within the given concentration range is'
Description[11]='established for the substances under investigation during the validation'
Description[12]='studies. No allowance is made for nonlinearity. Homogeneity of the bread'
Description[13]='samples has been estimated on the basis of the sampling method used. A number'
Description[14]='of feasible pesticide residue distribution scenarios were considered, and a'
Description[15]='simple binominal statistical distribution used to caluclate the standard'
Description[16]='uncertainty for the total included in the analysed sample. The scenarios, and'
Description[17]='the calculated relative standard uncertainties in the amount of pesticide in'
Description[18]='the final sample, were: Residue distributed on the top surface only: 0.58 (This'
Description[19]='scenario would arise in the case of decorative additions of whole grains to the'
Description[20]='surface of the bread) Residue distributed evenly over the surface only: 0.2'
Description[21]='Residue distributed evenly throgh the sample, but reduced in concentration by'
Description[22]='evaporative loss or decomposition close to the surface: 0.05 - 0.10 The second'
Description[23]='scenario was chosen as the most likely worst case. Therefore an uncertainty of'
Description[24]='0.2 was chosen.'
Vnom=1
Uexp=0.2
Fcov=1

[Correlations]
Description=0