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Poster Presentation 7-20
Effect of Lidocaine on Stability of an Ovalbumin Foam
G. Chauhan, S.M. Hartig, H.A. Kincaid, A.A. Lala S. Samsudin, R.A. Smith, T. Wang, S. Wyatt and R.D. Tanner
Department of Chemical Engineering Vanderbilt University Box 1604, Station B Nashville, TN 37235
Telephone: (615) 322-2061; Fax: (615) 343-7951; E-mail: rtanner@vuse.vanderbilt.edu
Foam fractionation is a separation process that utilizes a gas to physically pull surface active molecules out of solution into a foam phase. When that foam is collapsed, the resulting liquid may be more concentrated in the desired compound than the original solution. The process is sensitive to changes in gas flow rate, bulk liquid concentration, bulk pH, surface tension, and temperature. Foam fractionation can be used to separate hydrophobic molecules such as proteins, surfactants, and organic wastes from bulk solutions. Successful recovery of a protein (albumin) may depend on the stability of the foamate. In this study, foamate stability was tested by measuring the decay rate of a foam solution. Height measurements were taken as a function of time as the foam decayed. Interactions between an added component in the water solution, the hydrophobic steroid lidocaine, were investigated via surface tension experiments for possible application to the creation of a more stable foam to extinguish fires. Surface tension can be dependent on time, concentration of protein, and pH. Lidocaine was tested as a foam stabilizing agent. Initially, low lidocaine levels (~6.25 ppm-18.75 ppm) stabilized the foam. Subsequent additions of larger lidocaine amounts had an oscillatory effect on the time necessary for the foam to decay. Oscillatory results were also seen in the surface tension measurements as the lidocaine concentration increased. This result may be explained by albumin conformational changes caused by the addition of lidocaine. The protein may be exposing differing numbers of binding sites and hydrophobic groups as these structural changes occur, causing the oscillations. Another possible reason could be due to a mechanistic inhibition at high levels of lidocaine. This investigation demonstrates that lidocaine can increase the stability of an ovalbumin foam.
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