Determination of oceanic carbon dioxide using a carbonate-selective electrode.
Potentiometric properties of the PVC membrane-based electrodes prepared with molecular tweezer-type neutral carriers, 3,12-bis(TFAB)CA and deoxy-3,12-bis(TFAB)CA, and trifluoroacetyl-p-decylbenzene (TFADB) were measured in buffered electrolytes (0.1 M Tris-H2SO4, pH 8.6 and 8.0) and artificial seawater. It was observed that the deoxy-3,12-bis(TFAB)CA-based electrode provides greatly enhanced carbonate selectivity over chloride (log K(CO3(2-), Cl-)POT approximately -6) and other minor anions present in seawater. Thus, we explored the possibility of applying this new carbonate-selective electrode for direct determination of oceanic carbon dioxide. The total carbon dioxide (TCO2) level in surface Yellow Sea water was determined with the deoxy-3,12-bis(TFAB)CA-based electrode, Severinghaus-type CO2 gas sensor, and the traditional potentiometric titration methods. The results showed that the carbonate-selective electrode provides accurate oceanic TCO2 determination comparable to that obtainable with the other two methods. The analytical procedure based on a carbonate-selective electrode is clearly advantageous over other conventional methods: it does not require any sample pretreatment and extra reagents other than the standard calibration solutions, while providing the measured results directly and immediately.
Choi
Yong Suk
YS
Department of Chemistry, Kwangwoon University, Seoul, Korea.
Lvova
Larisa
L
Shin
Jae Ho
JH
Oh
Seong Hee
SH
Lee
Chang Suk
CS
Kim
Byeong Hyo
BH
Cha
Geun Sig
GS
Nam
Hakhyun
H
D002245:Carbon Dioxide / Q000032:analysis*; D002254:Carbonates / Q000032:analysis; D004563:Electrochemistry; D004566:Electrodes; D009792:Oceans and Seas; D012623:Seawater / Q000032:analysis* / Q000737:chemistry; D012680:Sensitivity and Specificity
D002254:Carbonates; D002245:Carbon Dioxide