[Header] Format=SMU ver=3 appl=GUMWB32 MR=0 SUR=0 SUP=0 UIP=1 UCR=0 status=2 FUEB=0 [Title] Title='Preparation of a calibration standard' Ref='' Date='08/29/2007' Version='' Author='' Description=11 Description[0]='This is the example A1 of the EURACHEM /' Description[1]='CITAC Guide "Quantifying Uncertainty in Analytical Measurement", Second' Description[2]='Edition.' Description[3]='' Description[4]='A' Description[5]='calibration standard of ca. 1000 mg\cdot\L^-1 is prepared from a' Description[6]='high purity metalic cadmium.' Description[7]='' Description[8]='After cleaning the surface of the high purity metal it is weighed and dissolved' Description[9]='in nitric acid in a' Description[10]='volumetric flask.' PictureCount=1 DCount=1 [Model] Model=7 Model[0]='{Calculation of the uncertainty of the volume}' Model[1]='' Model[2]='V = V_nominal * f_V\minus\calibration * f_V\minus\temperature * f_V\minus\repeatability;' Model[3]='' Model[4]='{Calculation of the uncertainty of the calibration standard}' Model[5]='' Model[6]='c_Cd = (k_mL * m * P) / V;' CE=1 CTC=1 [Components] CompOrder=3 Comp=9 Comp[0]=V Comp[1]=V_nominal_ Comp[2]=f_V\minus\calibration_ Comp[3]=f_V\minus\temperature_ Comp[4]=f_V\minus\repeatability_ Comp[5]=c_Cd_ Comp[6]=k_mL_ Comp[7]=m Comp[8]=P [COMP 0] Type=Temp Definition='Volume of the flask' Unit='mL' Description=0 Fcov=2 NomUnit= UncUnit= CovID=1 UncID=0 Vnom=100 Ustd=0.0664730521840743 Neff=1098 HB=0 HC=0 HR=0 IO=0 PictureCount=1 DCount=1 [COMP 1] Type=Const Definition='Nominal volume of the flask' Unit='mL' Description=4 Description[0]='The nominal volume is not associated with any uncertainties. The uncertainty of' Description[1]='the real volume of the flask has three components, calibration, temperature and' Description[2]='repeatability. These are included in the uncertainty budget as separate' Description[3]='factors.' Vnom=100 PictureCount=1 DCount=1 [COMP 2] Type=TypBTriangl Definition='Uncertainty contribution to the volume due to uncertainty in calibration of the flask' Unit='' Description=11 Description[0]='The manufacturer of the flask quotes the volume of the flask as 100 mL ±0.1 mL,' Description[1]='measured at a' Description[2]='temperature of 20°C. No further statement is made about the level of confidence' Description[3]='or the underlying distribution. An assumption is necessary to work with this' Description[4]='uncertainty statement. In this case a' Description[5]='triangular distribution is assumed. Since f_V\minus\calibration is a' Description[6]='multiplicative factor to the nominal volume, which is only used to introduce' Description[7]='the calibration uncertainty, it has the value 1. The halfwidth of limits' Description[8]='corresponds to the relative uncertainty as stated by the manufacturer (i.e. 0.1' Description[9]='mL /' Description[10]='100 mL).' Vnom=1 Hlim=0,001 PictureCount=1 DCount=1 [COMP 3] Type=TypBRectang Definition='Uncertainty contribution to the volume due to temperature variation' Unit='' Description=15 Description[0]='The flask has been calibrated at 20°C (manufacturer statement). The laboratory' Description[1]='temperature varies by ±4°C around this value. The uncertainty of the volume due' Description[2]='to temperature variations can be calculated from the estimate of the possible' Description[3]='temperature range and the coefficient of the volume expansion. The volume' Description[4]='expansion of the liquid is considerably larger than that of the flask, so only' Description[5]='the volume expansion of the liquid is considered. The coefficient of volume' Description[6]='expansion for water is 2.1\cdot\10^-4^°C^-1^, which is used here also for the' Description[7]='nitric acid solution. This leads to a' Description[8]='possible volume variation of ±(100 \cdot\ 4 \cdot\ 2.1\cdot\10^-4^) mL =' Description[9]='±0.084 mL. A' Description[10]='rectangular distribution is assumed for the temperature variation Since' Description[11]='f_V\minus\temperature is a' Description[12]='multiplicative factor to the nominal volume, which is only used to introduce' Description[13]='the temperature uncertainty, it has the value 1. The halfwidth of limits' Description[14]='corresponds to the possible volume variation as calculated above.' Vnom=1 Hlim=0,00084 PictureCount=1 DCount=1 [COMP 4] Type=TypASum Definition='temperaturabhängige Widerstandsänderung des zu kalibrierenden Widerstandes' Unit='' Description=10 Description[0]='The uncertainty due to the repeatability of the filings can be estimated from a' Description[1]='repeatability experiment on a' Description[2]='typical example of the flask used. The flask was filled and weighed ten times.' Description[3]='For the 100 mL flask this resulted in a' Description[4]='standard deviation of 0.02 mL. This is used directly as the standard' Description[5]='uncertainty. Since f_V\minus\repeatability is a' Description[6]='multiplicative factor to the nominal volume, which is only used to introduce' Description[7]='the repeatability uncertainty, it has the value 1' Description[8]='±' Description[9]='0.0002.' Vnom=1 Ustd=0,0002 Neff=9 PictureCount=1 DCount=1 [COMP 5] Type=Result Definition='Concentration of the calibration standard' Unit='mg/L' Description=0 Fcov=2 NomUnit= UncUnit= CovID=0 UncID=0 Vnom=1002.69972 Ustd=0.835199328725876 Neff=340 HB=1 HC=0 HR=1 IO=0 PictureCount=1 DCount=1 [COMP 6] Type=Const Definition='Conversion factor 1000 mL = 1 L' Unit='mL/L' Description=0 Vnom=1000 PictureCount=0 DCount=0 [COMP 7] Type=TypBNormal Definition='Mass of the metal' Unit='mg' Description=12 Description[0]='The mass of the cadmium is determined by a' Description[1]='tared weighing. The literature of the balance''s manufacturer identifies three' Description[2]='uncertainty sources for the tared weighing: the repeatablility, the readability' Description[3]='(digital resolution) of the balance scale and the contribution due to the' Description[4]='uncertainty in the calibration function of the scale. This calibration function' Description[5]='has two potential sources of uncertainty, identified as the sensitivity of the' Description[6]='balance and the linearity. The sensitivity can be neglected because the mass by' Description[7]='difference is done on the same balance over a' Description[8]='very narrow range. Bouyance correction is not considered here. Using data from' Description[9]='the calibration certificate of the balance and following the manufacturer''s' Description[10]='recommendations on uncertainty estimation, the uncertainty associated with the' Description[11]='mass of the cadmium is estimated as 0.05 mg.' Vnom=100,28 Uexp=0,05 Fcov=1 PictureCount=1 DCount=1 [COMP 8] Type=TypBRectang Definition='Purity of the metal' Unit='' Description=11 Description[0]='The purity of the metal is quoted in the suppliers certificate as 99.99 ±0.01%.' Description[1]='P' Description[2]='is expressed as mass fraction (g/g), and its value is therefore 0.9999±0.0001.' Description[3]='There is no additional information about the uncertainty. A' Description[4]='rectangular distribution is assumed.' Description[5]='' Description[6]='If the manufacturers procedure for cleaning the surface is strictly followed,' Description[7]='there should be no additional uncertainty contribution. There is no information' Description[8]='available about the completeness of the dissolution. Therefore one has to check' Description[9]='with a' Description[10]='repeated preparation experiment that this contribution can be neglected.' Vnom=0,9999 Hlim=0,0001 PictureCount=1 DCount=1 [Correlations] Description=0 [CalCorr] CNT=9 R[0,5]=-0.7980433 R[0,3]=0.7295802 R[0,2]=0.6141561 R[0,4]=0.3008738 R[5,7]=0.5985996 R[5,3]=-0.5822366 R[5,2]=-0.4901231 R[5,4]=-0.2401103 R[5,8]=0.0693208