Version 2 2023-06-23, 11:07Version 2 2023-06-23, 11:07
Version 1 2023-05-26, 16:14Version 1 2023-05-26, 16:14
journal contribution
posted on 2023-06-23, 11:07authored byW Hu, Paul HaddadPaul Haddad, K Hasebe, K Tanaka, P Tong, C Khoo
A new ion chromatographic method that is applicable to the direct determination of UV-absorbing inorganic anions in saline matrixes is described. An octadecylsilica column modified with a zwitterionic surfactant (3-(N,N-dimethylmyristylammonio)propanesulfonate) is used as the stationary phase, and an electrolytic solution is used as the eluent. Under these conditions, the matrix species (such as chloride and sulfate) are only retained weakly and show little or no interference. It is proposed that a binary electrical double layer (EDL) is established by retention of the eluent cations on the negatively charged (sulfonate) functional groups of the zwitterionic surfactant (forming a cation-EDL) and by retention of eluent anions on the positively charged (quaternary ammonium) functional groups of the zwitterionic surfactant (forming an anion-EDL). Sample anions are able to distribute into the cation-EDL and to form ion pairs with the EDL cations, while at the same time experiencing repulsion from the anion-EDL. Anions are therefore eluted in order of increased propensity to form ion pairs. The method has been applied to the determination of bromide, nitrate, and iodide in artificial seawater, giving detection limits of 0.75 ppb for bromide, 0.52 ppb for nitrate, and 0.8 ppb for iodide using UV absorbance detection at 210 nm and relative standard deviations of <1.2%. Real seawater samples have also been analyzed successfully.
History
Publication title
Analytical Chemistry
Volume
71
Issue
8
Article number
8
Number
8
Pagination
1617-1620
ISSN
0003-2700
Department/School
Chemistry
Publisher
American Chemical Society
Publication status
Published
Rights statement
Copyright Copyright 1999 American Chemical Society
Repository Status
Open
Socio-economic Objectives
280105 Expanding knowledge in the chemical sciences