Learning to make membranes for ISEs

I just spent two days at the University of Geneva learning to make polymer membranes for Ion Selective Electrodes (ISE). A post-doc (Gaston) working in Eric Bakker's research group helped me with the process. Making the membranes was actually quite easy - with the right tools and recipe, we made 3 membranes that look like small contact lenses. The membranes are being conditioned now in different concentrations of Ag. The goal of this is to use the ISEs to decrease the detection limit of Ag+ in solution and minimize interference associated with the matrix. I go back on Monday to put the ISE together and start optimizing the solutions for my experiments.

These are the polymer membranes... For the scale, the unit conversion is that one Swiss half franc (shown here) is about the size of a US dime...

Here are two papers to look at if you want to learn more about ISEs for trace metal analysis: Note these are not for the squeamish... start with Bakker and Pretsch 2002 as an nice introduction.

• Bakker, E. and E. Pretsch. 2002. The New Wave of Ion-Selective. Analytical Chemistry, August 1: 420A - 426A.
• Szigeti, Z., Malon, A., Vigassy, T. Csokai, V., Grün, A., Wygladacz, K., Ye, N., Xu, C., Chebny, V., Bitter, I., Rathore, R., Bakker, E., and E. Pretsch. 2006. Novel Potentiometrix and Optical Silver Ion-Selective Sensors with Subnanomolar Detection Limits. Analytica Chimica Acta, 572:1-10.
  

Great Video -

This video (Caught in a Bad Project) made the rounds at Eawag several months ago, and I dare say the song still gets stuck in my head on occasion. Anyone who has done a scientific research based graduate degree will find parts of this spot on. I particularly love what they used for the costumes - 10 ml pipette tips make up the bodice of one outfit with biohazard bags completing the skirt. The other is lovely compliment of absorbent lab bench pads... brilliant!