科研之友
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摘要
In this work, a flow electrolytic cell for ion transfer across a DCE/W interface was manufactured from a block of Daiflon (Polychlorotrifluoroethylene resin). The cell was compact, and had a structure in which the DCE and W phases were separated by a membrane. To evaluate the cell performance, voltammograms of the promoted ion transfer of alkali and alkaline earth metal ions were measured. As ionophores for the ion transfer, 12-crown-4, 15-crown-5 and dibenzo-18-crown-6 were employed. Based on the measurements, the cell was improved, and various parameters (flow rate and the potential added) for amperometry were optimized. Two membranes separating the DCE and W phases, the cellulose dialysis membrane and the PTFE (polytetrafluoroethylene) hydrophilic membrane filter were tested. When the dialysis membrane was used, ion-transfer occurred in the dialysis membrane at the DCE/dialysis membrane/W interface. On the other hand, when the membrane filter was used, ion-transfer occurred in the W phase in the vicinity of the DCE/membrane filter/W interface. In practice, since the membrane filter was chemically resistant to DCE and mechanically stronger than the dialysis membrane, flow-injection amperometry was carried out with the membrane filter. Subsequently, the selectivity among the alkali and alkaline earth metal ions was examined. As a result, it was confilined that Na+ could be selectively detected when 12C4 was employed. Based on this result, Na+ in soy sauce was determined. The determination value was 2.99 +/- 0.14 mol dm(-3) (n = 4). The value of 2.99 mol dm(-3) was in agreement with the certified value of 2.80 mol dm(-3) within the 95 %-confidence limit. The relative standard deviation was 4.7 %, which shows a reasonable reproducibility of this determination method using the electrolytic cell. The flow electrolytic cell manufactured in this work is easily handled, and can be used in actual analyses of various ions in the aid of flow injection amperometry.
- 出版日期2016-3
