Mass Transfer Characteristics of Solvent Extraction into a Single Drop at the Tip of a Syringe Needle
Michael A. Jeannot and Frederick F. Cantwell*
Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
Received for review August 12, 1996. Accepted October 22, 1996.
The amount of a sample compound extracted into a 1-L drop of n-octane suspended in a stirred aqueous solution from the tip of a microsyringe needle is measured by gas chromatography (GC) as a function of time. The observed extraction rate curve is first order and yields the overall mass transfer coefficient for the sample compound, o. For a given compound, o varies linearly with stirring rate. Among the four compounds malathion, 4-methylacetophenone, 4-nitrotoluene, and progesterone, at a given stirring rate, o is linearly proportional to the diffusion coefficient of the compound (Daq). This supports the film theory of convective-diffusive mass transfer, as opposed to the penetration theory. The relative standard deviation of the GC signal for 4-methylacetophenone after a 1.00 min extraction at 1500 rpm is 1.5%, which suggests that the system exhibits excellent potential as a tool for rapid analysis by solvent extraction/GC.
Automated solid phase dynamic extraction - Extraction of organics using a wall coated syringe needle
J. Lipinski A1
A1 SOFIA GmbH, Rudower Chaussee 29, 12489 Berlin, Germany e-mail: JLipinski@sofia.fta-berlin.de