Meeting Abstract

P2.84  Friday, Jan. 4  Determination of Larval Anuran Gut pH Levels with a Newly Developed Solid State Micro-Electrode BESSLER, S.M.*; CLEVES, A; LUBBERS, B; DURTSCHE, R.D.; University of Alabama; Northern Kentucky University; Northern Kentucky University; Northern Kentucky University besslers@gmail.com

Evaluation of environmental pH conditions on small spatial (micro) scales is often limited by the size of the measuring instrument. We therefore designed and fabricated a solid-state microelectrode for pH measurements in a variety of microenvironments. The electrodes were constructed from flame pulled borosilicate glass pipettes with a platinum core and an iridium oxide pH sensing layer. The microprobe tip (~ 2-10 �M dia.) was coated with a Nafion ion exchange resin to protect the pH sensing layer. Temperature (10-40 �C) and stirring speed (50-100 rpm) tests found these probes to be highly stable, and to provide highly accurate readings (> 94%) over a wide range (2-10) of pH levels. In our initial use of these probes, we measured the luminal pH along the gastrointestinal tracts of green frog tadpoles (Rana clamitans). Using a micromanipultor, we punctured the wall of the extracted gastrointestinal tract with the electrode and recorded luminal pH at 10 locations. We found luminal pH of the tadpole gut to vary with respect to position. Luminal pH of the stomach ranged between 2.5 – 2.6, whereas, pH of the small and large intestine was higher, ranging from 3.7 – 3.9. These pH electrodes provide an inexpensive ($35 per probe) and accurate method to measure pH at small spatial scales, applicable for use in small organisms and in mapping the luminal to tissue gradient in pH.