Analytical Sciences


Abstract − Analytical Sciences, 18(3), 247 (2002).

Achieving High Time-Resolution with a New Flow-through Type Analyzer for Total Inorganic Carbon in Seawater
Hideshi KIMOTO,* Ken NOZAKI,*2 Setsuko KUDO,*3 Ken KATO,*2 Akira NEGISHI,*2 and Hajime KAYANNE*3,*4
*1 Kimoto Electric Co., Ltd., Funahashi, Tennoji, Osaka 543-0024, Japan
*2 Energy Electronics Institute, National Institutes of Advanced Industrial Science and Technology, AIST Tsukuba Central 2, Umezono, Tsukuba 305-8568, Japan
*3 Japan Science and Technology Corporation, Department of Earth and Planetary Science, The University of Tokyo, Hongo, Bunkyo, Tokyo 113-0033, Japan
*4 Department of Earth and Planetary Science, The University of Tokyo, Hongo, Bunkyo, Tokyo 113-0033, Japan
A fully automated, continuous-flow-through type analyzer was developed to observe rapid changes in the concentration of total inorganic carbon (CT) in coastal zones. Seawater and an H3PO4 solution were fed into the analyzer's mixing coil by two high-precision valveless piston pumps. The CO2 was stripped from the seawater and moved into a carrier gas, using a newly developed continuous-flow-through CO2 extractor. A mass flow controller was used to assure a precise flow rate of the carrier gas. The CO2 concentration was then determined with a nondispersive infrared gas analyzer. This analyzer achieved a time-resolution of as good as 1 min. In field experiments on a shallow reef flat of Shiraho (Ishigaki Island, Southwest Japan), the analyzer detected short-term, yet extreme, variations in CT which manual sampling missed. Analytical values obtained by the analyzer on the boat were compared with those determined by potentiometric titration with a closed cell in a laboratory: CT(flow-through) = 0.980·CT(titration) + 38.8 with r2 = 0.995 (n = 34; September 1998).