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Volume 9
Journal of Analytical & Bioanalytical Techniques
Mass Spectra & Analytika 2018
September 19-20, 2018
September 19-20, 2018 Singapore
World Congress on
Mass Spectrometry and Analytical Techniques
Maria Ramos Payan et al., J Anal Bioanal Tech 2018, Volume 9
DOI: 10.4172/2155-9872-C2-031
Study of the microchip device’s geometry based on the distribution constant of the analytes
Maria Ramos Payan and Garcia Gonzalez
University of Seville, Spain
T
he chip geometry is one of the most important parameters to optimize since the length, width and depth will determine
the efficiency of the extraction. On the other hand, the efficiency of the liquid membrane extraction depends on several
different parameters. These include flow rate, dimensions of the channels of the membrane holder, the membrane porosity and
thickness, chemical composition of the phases, kinetic and thermodynamic properties. Basically, two main sets of conditions
for SLM extraction can be distinguished. With donor-controlled conditions the rate of extraction is controlled by the mass
transfer in the donor phase. This is the case when the distribution coefficient K
d
between the organic membrane phase and
the donor phase is relatively large (K
d
>10) for the analyte molecules. Diffusion coefficients in the phases also play a role here
when liquid phase micro extraction is the technique used for the extraction. With donor-controlled conditions, the extraction
efficiency should increase with the flow rate of the donor buffer. Also, if K
d
is small, or the mass transfer in the membrane is
unusually low, the mass transfer in the membrane phase controls the rate of extraction (membrane-controlled conditions). In
that case, the donor flow rate per seconds is not important and the extraction efficiency is determined by the total extraction
time. Then, the dimensions of the channel have a large influence on the recovery. The depth of the donor channel should be as
low as possible so that a large part of the sample is in contact with the membrane. This is particularly important when the mass
transfer in the donor phase is the limiting factor (that is, K
d
is high). On the other hand, a very shallow channel (<0.1 mm) is
hard to machine and can cause stoppage, especially with viscous samples such as plasma. To achieve a high recovery, a large
exposed membrane area is preferable, but a too wide channel can cause bulging of the membrane, while the length is limited by
the back pressure arising in the channel. The exposed membrane area is also determined by the maximum acceptable volume
and possible depth of the acceptor channel. Based on this discussion, we propose the most suitable channels dimension for a
microchip device based on the distribution constant of each analyte and the time required to be extracted through the support
liquid membrane by passive diffusion.
Biography
Maria Ramos Payan has pursued her PhD from University of Seville, Spain and Postdoctoral studies from University of Copenhagen, Denmark, University of North
Carolina, USA and Microelectronic National Center of Barcelona, Spain. She is the Leader of the microfluidic research line. She has published more than 30 papers
in reputed journals and has been serving as an Editorial Board Member of repute.
ramospayan@us.es