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Schulte, Ulrike, Weihmann, Jenny and Mansfeldt, Tim (2010). Optimized enrichment and purification of ferrocyanide for C-13/12 and N-15/14 isotope analysis of aqueous solutions. Water Res., 44 (18). S. 5414 - 5423. OXFORD: PERGAMON-ELSEVIER SCIENCE LTD. ISSN 0043-1354

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Abstract

The occurrence of ferrocyanide, Fe(CN)(6)(4-), in aqueous environments is of concern, since it is potentially hazardous. For tracing the source of ferrocyanide in contaminated water we developed a method that relies on the determination of the stable isotope ratios of C-13/C-12 and N-15/N-14 of this complexed cyanide (CN) after precipitating it as cupric ferrocyanide, Cu-2[Fe(CN)(6)]center dot 7H(2)O. The precipitate was combusted and the isotope ratios were determined by continuous flow isotope ratio mass spectrometry. At first, ferrocyanide enrichment from synthetic water containing cyanide with known isotopic composition was studied by using six commercial anion-exchange resins. Five resins revealed a quick and complete sorption of ferrocyanide. A nearly quantitative desorption was achieved using NaCl solutions of 5 and 10% by weight for four resins. Subsequent determination of the delta C-13(CN) and delta N-15(CN) values of the ferrocyanide revealed that no significant isotope fractionation occurred during this procedure. These results were reproduced even in column experiments using larger water volumes. Potential interferences were also addressed. Sulfate in excess competes for exchange sites but can be precipitated as BaSO4 prior to ferrocyanide enrichment. Non-cyanide carbon compounds may co-precipitate with cupric ferrocyanide, thus possibly modifying the isotope ratios. However, neither dissolved inorganic carbon nor highly soluble organic compounds did interfere with the method. Poorly soluble organics like BTEX and PAH can be eliminated by passing the samples through appropriate adsorber resins in a prior step. The proposed method is an excellent way of precise determination of the stable cyanide-carbon and cyanide-nitrogen isotope ratios in ferrocyanide-containing aqueous samples, which was successfully applied to four contaminated groundwater samples since measured aqueous isotopes ratios match those of corresponding cyanide-bearing solid wastes. (C) 2010 Elsevier Ltd. All rights reserved.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Schulte, Ulrike UNSPECIFIED UNSPECIFIED UNSPECIFIED Weihmann, Jenny UNSPECIFIED UNSPECIFIED UNSPECIFIED Mansfeldt, Tim UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-496307
DOI:	10.1016/j.watres.2010.06.041
Journal or Publication Title:	Water Res.
Volume:	44
Number:	18
Page Range:	S. 5414 - 5423
Date:	2010
Publisher:	PERGAMON-ELSEVIER SCIENCE LTD
Place of Publication:	OXFORD
ISSN:	0043-1354
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language CONTAMINATED SOILS; STABLE CARBON; WATER-QUALITY; CYANIDE; IDENTIFICATION; COMPOUND; WASTES Multiple languages Engineering, Environmental; Environmental Sciences; Water Resources Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/49630