pFI Method for TIC (Carbondioxide)
Sample, containing carbonate and bicarbonate releases CO2, when merged with acid, reagent #1 solution. CO2 passes across a gas-permeable membrane into a acceptor stream (reagent # 2), containing bromothymol blue in basic (blue) form. This decreases pH, and the color change
(to yellow) is proportional to the initial Total Inorganic Carbon (TIC) content in the sample.
The flow rate is programmed to slow, while the sample zone is in contact with the diffusion membrane, and thus, with the increasing dwell time at 2% flow rate, the amount of CO2 transported through the membrane increases (A). By changing dwell time from 15 seconds to 60 seconds the sensitivity and LOD of the assay improves 10 times (B,C,D). Sample volume 300 mcrL, flow rate: 2% at dwell time, 50% trough flow cell. 10 cm light path, 2 cm diffusion path. 0.0005% BTB indicator.
1.2.37.
A
B
