title: Bias from two analytical laboratories involved in a long-term air monitoring program measuring organic pollutants in the Arctic: a quality assurance/quality control assessment.
abstract: Initiated in 1992, air monitoring of organic pollutants in the Canadian Arctic provided spatial and temporal trends in support of Canada's participation in the Stockholm Convention of Persistent Organic Pollutants. The specific analytical laboratory charged with this task was changed in 2002 while field sampling protocols remained unchanged. Three rounds of intensive comparison studies were conducted in 2004, 2005, and 2008 to assess data comparability between the two laboratories. Analysis was compared for organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in standards, blind samples of mixed standards and extracts of real air samples. Good measurement accuracy was achieved for both laboratories when standards were analyzed. Variation of measurement accuracy over time was found for some OCPs and PCBs in standards on a random and non-systematic manner. Relatively low accuracy in analyzing blind samples was likely related to the process of sample purification. Inter-laboratory measurement differences for standards (<30%) and samples (<70%) were generally less than or comparable to those reported in a previous inter-laboratory study with 21 participating laboratories. Regression analysis showed inconsistent data comparability between the two laboratories during the initial stages of the study. These inter-laboratory differences can complicate abilities to discern long-term trends of pollutants in a given sampling site. It is advisable to maintain long-term measurements with minimal changes in sample analysis.
authors: ECO Environmental Chemists, 64 Samuel Oster Avenue, Thornhill, Ontario L4J7C8, Canada. yushan.su@utoronto.ca
authors: Yushan
authors: Y
authors: Su
authors: Hayley
authors: H
authors: Hung
authors: Gary
authors: G
authors: Stern
authors: Ed
authors: E
authors: Sverko
authors: Randy
authors: R
authors: Lao
authors: Enzo
authors: E
authors: Barresi
authors: Bruno
authors: B
authors: Rosenberg
authors: Phil
authors: P
authors: Fellin
authors: Henrik
authors: H
authors: Li
authors: Hang
authors: H
authors: Xiao
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000032:analysis; D001110:Arctic Regions; D015982:Bias; D002170:Canada; D004784:Environmental Monitoring / Q000592:standards*; D008401:Gas Chromatography-Mass Spectrometry; D006843:Hydrocarbons, Chlorinated / Q000032:analysis*; D007753:Laboratories / Q000592:standards*; D059021:Laboratory Proficiency Testing; D016014:Linear Models; D010575:Pesticides / Q000032:analysis*; D011078:Polychlorinated Biphenyls / Q000032:analysis*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D006843:Hydrocarbons, Chlorinated; D010575:Pesticides; D011084:Polycyclic Aromatic Hydrocarbons; D011078:Polychlorinated Biphenyls