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|Title:||Evaluation of Performance Characteristics of Multistep Analytical Methods from Collaborative Study of Linked Samples|
|Authors:||DUEWER David L.; SCHANTZ Michele M.; PARRIS Reenie M.; ULBERTH FRANZ|
|Citation:||ANALYTICAL CHEMISTRY vol. 80 no. 19 p. 7327-7335|
|Publisher:||AMER CHEMICAL SOC|
|Type:||Articles in periodicals and books|
|Abstract:||Following unexpectedly variable results from an international comparison study of the determination of selected polychlorinated biphenyl (PCB) congeners in shellfish tissue, a group of national metrology institutes collaboratively explored the analytical characteristics of their measurement systems using a designed study with four sample materials. This "Uncertainty Suite" consisted of a 10-congener mixture of PCBs in the relatively non-volatile iso-octane, a 5-congener mixture in relatively volatile methylene chloride, a methylene chloride extract of freeze-dried mussel (Mytilus edulis) tissue, and the (homogenized) mussel tissue itself. These samples presented the participants' measurement processes with a nested series of analytical challenges. Data evaluation tools were developed to combine and visualize measurement results for the different congeners of interest for each material and, exploiting the relationships among the samples, to help identify causes for observed changes in performance. In addition to characterizing individual measurement processes, 1) the limiting sources of measurement uncertainty were found to be chromatographic separation and signal quantification in a natural matrix, 2) the achievable among-participant measurement accuracy for PCB calibration solutions is appr. 1.9 % over the mass fraction range from 40 ng/g to 500 ng/g, and 3) the achievable among-participant measurement precision for the determination of PCB congeners in mussel tissue at levels above 0.5 ng/g mass fraction is appr. 5,4%.|
|JRC Directorate:||Health, Consumers and Reference Materials|
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