Continuous flow analysis of iron (III) in seawater using a chalcogenide glass ion-elective electrode

Continuous pow analysis (CFA) is suitable for rapid and reliable determinat ion of free Fe-III in organic-free, UV-oxidized seawater when used in conju nction with an extrapolation method that predicts the steady-state potentia l of an Fe-III chalcogenide glass ion-selective electrode (ISE) by using in itial data associated with a step-wise change in aFe(3+). It is shown that the CFA technique yields a Nernstian response of a 30 mV per decade change in aFe(3+) in saline citrate buffers in the range of 10(-22) to 10(-16) M F e3+. Validation of the CFA technique in organic-free, UV-oxidized seawater has demonstrated that the response of the Fe-III ISE is internally consiste nt with the well-known inorganic speciation equilibria occurring in natural seawater. (C) 1999 John Wiley & Sons, Inc.