Uncertainty associated to the analysis of organochlorine pesticides in water by solid-phase microextraction/gas chromatography-electron capture detection - Evaluation using two different approaches

• Type: Article in International Scientific Journal
• Date: 2006

Authors

Nuno Ratola (Author) Other; Lucia Santos (Author) FEUP; Paulo Herbert (Author) Other; Arminda Alves (Author) FEUP

Journal

Title: Analytica Chimica Acta

Vol. 573

Pages: 202-208

ISSN: 0003-2670

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 33 Citations

ISI Web of Science

Scopus - 42 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

CORDIS: Natural sciences > Environmental science

Other information

Authenticus ID: P-004-JHP

DOI: 10.1016/j.aca.2006.03.065

Abstract (EN): As the performances of analytical instrumentation are being gradually enhanced, the limits of detection become increasingly lower, allowing more environmental contaminants to be determined in different matrices. Problems emerge when dealing with data from different origins, once the uncertainty of the results is difficult to be compared, especially if its calculation procedure is rather different, as very often happens. Samples of two organochlorine pesticides of somewhat opposite characteristics (lindane and heptachlor, classified as persistent organic pollutants-POPs) were analyzed in aqueous media using headspace solid-phase microextraction (SPME) prior to gas chromatography-electron capture detection (GC-ECD) and this methodology was in-house validated. Detection limits of 0.097 and 0.050 mu g l(-1), average intermediate precision of 11.6% and 27.5%, and average recovery of 95.6% and 103.0%, for lindane and heptachlor, respectively, were found. In the absence of available interlaboratory studies to assess the reliability of the results, the expanded uncertainty was calculated following two different approaches (bottom-up/Eurachem and modified top-down) and the results were compared. Globally it was clearly shown that, for both pesticides, the lower the concentration range, the higher the uncertainty associated to the results. Expanded uncertainties estimated by bottom-up/Eurachem approach varied from 5 1% to 14% for a lindane concentration range of 0.1-1 mu g l(-1), and from 48% to 24% for a heptachlor range of 0.1-2 mu g l(-1). Modified top-down approach pointed to 44% (lindane and heptachlor) in the same ranges, meaning that a uniform procedure for uncertainty estimation should be adopted.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7