title: How to improve reliability in groundwater analysis: over a decade of experience with external quality control in field campaigns on volatile halogenated compounds.
abstract: The reliability in measurement results obtained during environmental monitoring is crucial for the assessment and further planning of remediation efforts on the respective contaminated sites by the responsible authorities. A case study concerned with groundwater contaminated with perchloroethylene, trichloroethylene and 1,1,2-trichlorotrifluoroethane including their degradation products which involves private contract laboratories and an independent provider of quality assurance (QA) is presented. The experience gained with biannual monitoring campaigns over 14 years indicates that the selection of contractors on basis of accreditation status and successful performance in interlaboratory comparisons are not sufficient. Rather the auditing of the contractors by the QA provider prior to each campaign and the crosschecking of selected monitoring samples by the QA provider led to a lasting improvement of reliability in the contractors' measurement results. A mean deviation of 20% from the reference value determined by the QA provider for the crosschecked samples was reached.
authors: BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Strasse 11, 12489 Berlin, Germany. ute.dorgerloh@bam.de
authors: Ute
authors: U
authors: Dorgerloh
authors: Roland
authors: R
authors: Becker
authors: Axel
authors: A
authors: Lutz
authors: Wolfram
authors: W
authors: Bremser
authors: Sabine
authors: S
authors: Hilbert
authors: Irene
authors: I
authors: Nehls
mesh_terms: D064227:Chlorofluorocarbons, Ethane; D005617:Chlorofluorocarbons, Methane / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods*; D060587:Groundwater / Q000737:chemistry*; D054879:Halogenation; D011786:Quality Control; D013750:Tetrachloroethylene / Q000032:analysis; D014241:Trichloroethylene / Q000032:analysis; D055549:Volatile Organic Compounds / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data; D060753:Water Quality / Q000592:standards*
chemical_list: D064227:Chlorofluorocarbons, Ethane; D005617:Chlorofluorocarbons, Methane; D055549:Volatile Organic Compounds; D014874:Water Pollutants, Chemical; C005850:1,1,1-trichloro-2,2,2-trifluoroethane; D014241:Trichloroethylene; D013750:Tetrachloroethylene