Development of a gas diffusion probe for the rapid measurement of pCO2 in aquatic samples

Abstract

A probe for the direct measurement of the partial pressure of carbon dioxide (pCO2) in aqueous samples is described. It consists of a gas permeable membrane tube containing a flowing acceptor stream of bromothymol blue indicator solution. Carbon dioxide diffuses across the membrane causing a pH change in the acceptor. This pH change decreases the absorbance of the acid-base indicator which is detected photometrically, with high sensitivity using a multi-reflection photometric detector with an LED light source. Unlike many other common methods used to measure pCO2, this probe has the advantage of not requiring sampling to perform measurements, and avoids potential losses and contamination. Th..