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Evaluation of passive samplers with neutral or ion-exchange polymer coatings to determine freely dissolved concentrations of the basic surfactant lauryl diethanolamine: Measurements of acid dissociation constant and organic carbon-water sorption coefficient.

Authors :
Wang F
Chen Y
Hermens JL
Droge ST
Source :
Journal of chromatography. A [J Chromatogr A] 2013 Nov 08; Vol. 1315, pp. 8-14. Date of Electronic Publication: 2013 Sep 14.
Publication Year :
2013

Abstract

A passive sampler tool (solid-phase microextraction, SPME) was optimized to measure freely dissolved concentrations (Cw,free) of lauryl diethanolamine (C12-DEA). C12-DEA can be protonated and act as a cationic surfactant. From the pH-dependent sorption to neutral SPME coatings (polyacrylate and PDMS), a pKa of 8.7 was calculated, which differs more than two units from the value of 6.4 reported elsewhere. Polyacrylate coated SPME could not adequately sample largely protonated C12-DEA in humic acid solutions of pH 6. A new hydrophobic SPME coating with cation-exchange properties (C18/SCX) sorbed C12-DEA 100 fold stronger than polyacrylate, because it specifically sorbs protonated C12-DEA species. The C18/SCX-SPME fiber showed linear calibration isotherms in a concentration range of <1 nM-1 μM (well below the CMC). Using the C18/SCX-SPME fibers, linear sorption isotherms to Aldrich humic acid at pH 6 (ionic strength 0.015 M) were measured over a broad concentration range with a sorption coefficient of 10(5.3).<br /> (Copyright © 2013 Elsevier B.V. All rights reserved.)

Details

Language :
English
ISSN :
1873-3778
Volume :
1315
Database :
MEDLINE
Journal :
Journal of chromatography. A
Publication Type :
Academic Journal
Accession number :
24094752
Full Text :
https://doi.org/10.1016/j.chroma.2013.09.041