Divalent iron (Fe2+) is an important nutrient for many living organisms and is present in places such as oceans, surface water and acid mine drainage. Total dissolved iron is typically analyzed by techniques such as inductively coupled plasma mass spectrometry or colorimetrically. However, these methods are time consuming, require expensive stationary instrumentation, sample pretreatment, specialists to operate and are not capable of direct determination of the Fe2+ concentration.. Therefore, there is a significant need for mobile low-cost devices that can provide accurate and rapid assessment of dissolved Fe2+. Here we developed a novel all-solid-state contact Fe2+ selective electrode by immobilizing a sensing membrane on the surface of an all-solid-state contact which consists of a mixture of graphite-epoxy resin in suitable ratio. Selectivity of the electrode was tested in the concentration range 1×10−6 to 1x10−1 M Fe2+ by using a multi-channeled computer controlled potentiometer. Fe2+ (1×10−2 M) solutions at pH values between 2 and 8 were used to observe the working pH range of the electrode. The response time of the electrode was measured for Fe2+ solutions by the additions of different Fe2+ concentrations. All potentiometric measurements were conducted inside an anoxic glovebox. We found that the electrode displayed high selectivity to Fe2+ ions with a slope of 33.1±1 mV/decade. The response time of the electrode was 25 seconds and the working pH range was between 3 and 5.5. The development of this Fe(II) ion-selective electrode will allow for rapid inexpensive in-situ analyses of Fe2+ in complex environmental field samples.

Development of an all-solid-state Fe(II) ion-selective electrode

255th National Meeting (2018)

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