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Study of mass transfer in a dynamic hollow‐fibre liquid phase microextraction system
Author(s) -
Hansson Helena,
Colmsjö Anders,
Nilsson Ulrika
Publication year - 2010
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.200900539
Subject(s) - repeatability , extraction (chemistry) , chemistry , diffusion , mass transfer , chromatography , analytical chemistry (journal) , membrane , phase (matter) , thermodynamics , organic chemistry , biochemistry , physics
The extraction characteristics of a dynamic hollow‐fibre liquid phase microextraction system were investigated by studying the mass transfer and diffusion rates of dinitrophenols from plasma samples over the liquid membrane (dihexylether). The measured diffusion coefficients were compared with theoretical values calculated from Stokes diameters. The diffusion mechanism was simulated by computer and the most polar compounds, 2,4‐dinitrophenol and 4,6‐ o ‐dinitrocresol, had associated diffusion coefficients that were close to the calculated theoretical values. 2‐sec‐Butyl‐4,6 dinitrophenol and 2‐tert‐butyl‐4,6‐dinitrophenol, the compounds with the highest log P values, were retained by the polypropylene membrane, which reduced the experimentally observed diffusion rates to about half of the theoretical values. The retention was most likely due to dispersive forces interacting with the pore inner walls. Extraction was linearly correlated with time for all compounds and the repeatability was high (RSDs 7–11%), even for the shortest extraction times. Method LOD as the amount injected ranged between 0.3 and 3.1 ng for an extraction cycle of 213 s.