Document Detail

Naphthenic acids and other acid-extractables in water samples from Alberta: what is being measured?
MedLine Citation:
PMID:  20825979     Owner:  NLM     Status:  MEDLINE    
There is increasing international interest in naphthenic acids (NAs, classical formula C(n)H(2n+Z)O(2)) found in the oil sands from Alberta, Canada and in petroleum from around the world. The complexity of NAs poses major analytical challenges for their quantification and characterization. We used ultrahigh resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR MS) to probe the make up of NAs from various sources by searching for peaks corresponding to the formula C(n)H(2n+Z)O(x), for combinations of n=8 to 30, Z=0 to -12, and x=2 to 5. The sources included three commercial NAs preparations, and the acid-extractable organics from eight oil sand process-affected waters (OSPW) and from six surface fresh waters. Extracts from OSPW contained between 1 and 7% sulfur. The mass spectra showed between 300 and 1880 peaks, with >99% of the peaks having m/z between 145 and 600. In most cases, <20% of the peaks were assigned as classical NAs (x=2) and oxy-NAs (x=3 to 5). The classical NAs from the OSPW were predominantly Z=-4 and -6, whereas those from the fresh waters were mainly Z=0, with palmitic and stearic acids being the major components in the fresh waters. Remarkably, when the peak abundances were considered, <50% of the total abundance could be assigned to the classical and oxy-NAs. Thus, >50% of the compounds in the extracts of OSPW were not "naphthenic acids". Based on these findings, it appears that the term "naphthenic acids", which has been used to describe the toxic extractable compounds in OSPW, should be replaced by a term such as "oil sands tailings water acid-extractable organics (OSTWAEO)". Classical and oxy-NAs are components of OSTWAEO, but this term would not be as misleading as "naphthenic acids".
David M Grewer; Rozlyn F Young; Randy M Whittal; Phillip M Fedorak
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-09-09
Journal Detail:
Title:  The Science of the total environment     Volume:  408     ISSN:  1879-1026     ISO Abbreviation:  Sci. Total Environ.     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-10-25     Completed Date:  2010-12-13     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0330500     Medline TA:  Sci Total Environ     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  5997-6010     Citation Subset:  IM    
Copyright Information:
Copyright © 2010 Elsevier B.V. All rights reserved.
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
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MeSH Terms
Carboxylic Acids / analysis*,  chemistry
Environmental Monitoring
Spectrometry, Mass, Electrospray Ionization
Water Pollutants, Chemical / analysis*,  chemistry
Reg. No./Substance:
0/Carboxylic Acids; 0/Water Pollutants, Chemical; 1338-24-5/naphthenic acid

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