CENTRO DE METROLOGIA QUIMICA

CALCULATION OF UNCERTAINTIES FOR THE REPORT OF ANALYSES IN SIM. 8. P1 CALCULATION OF UNCERTAINTIES FOR THE REPORT OF ANALYSES IN SIM.8.P1.2 (CHLORINATED PESTICIDES IN HEXANE) 1

ANALYTICAL MEASUREMENT Gas Chromatograph Perkin-Elmer Model 8000 series 2 with Electron Capture Detector and manual injector Column Phase, BP- 5 Col. Length, 50.00 m Col. i.d., 0.33 mm Col. film thickness, 0.50 µm 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 1

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 1

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 1

GRAVIMETRIC PREPARATION OF STANDARDS

BRACKETING SCHEME 120 58 40 20 8 4,4 ‘ -DDE ng/g 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 1

THE UNCERTAINTY ESTIMATION PROCESS

BRACKETING AND INTERNAL STANDARD (AH/AIS) (AS/AIS) (AL/AIS) CS/CIS CH/CIS CL/CIS Sample concentration is calculated trough the equation: 1

IDENTYFYING UNCERTAINTY SOURCES Csample

QUANTIFYING UNCERTAINTY SOURCES Csample

UNCERTAINTY OF THE STANDARDS

UNCERTAINTY OF THE STANDARDS

GRAVIMETRIC PREPARATION OF STANDARDS Ampoules SMR 2261 sol. INT 1 sol. INT 3 Standard Brack low Brack high IS – sol. INT IS solid 0.5% 0.6% 0.6% 0.6% 0.6%

IDENTYFYING UNCERTAINTY SOURCES Csample

IDENTYFYING UNCERTAINTY SOURCES Csample

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

QUANTIFYING UNCERTAINTY SOURCES

UNCERTAINTY STANDARD OF THE SIGNAL 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:

UNCERTAINTY STANDARD OF THE SIGNAL

QUANTIFYING UNCERTAINTY SOURCES

CALCULATING THE CONCENTRATION

UNCERTAINTY CONTRIBUTIONS

CONCENTRATION AND UNCERTAINTY VALUES FOR THE SAMPLE SIM.8.P1.2