|Budget Amount *help
¥6,100,000 (Direct Cost : ¥6,100,000)
Fiscal Year 1995 : ¥1,900,000 (Direct Cost : ¥1,900,000)
Fiscal Year 1994 : ¥4,200,000 (Direct Cost : ¥4,200,000)
The aims of the present research are to develop pH sensors of high response characteristics for use in nonaqueous solutions and to show their applicability in the study of nonaqueous solution chemistry.
1. pH-sensitive field effect transistors (pH-ISFETs) of silicon nitride (Si_3N_4) and tantalum oxide (Ta_2O_5) types and a pH-sensitive iridium oxide electrode, all of which are durable in nonaqueous solutions, were prepared and their response characteristics, i. e., sensitivities, response rates and measurable pH ranges, were examined in various nonaqueous solvents with relative permittivities ranging from high to very low (<3) values and compared with those for a conventional pH-glass electrode. The pH-ISFETs and the iridium oxide electrode responded with Nernstian slopes in all the solvents studied. Those new pH sensors responded much faster than the glass electrode. The response of the Si_3N_4-type pH-ISFET was so fast that a pH-titration curve could be obtained in 20-30 seconds, though it took several hours with the glass electrode. The new pH-sensors could also work as a sensor for proton solvation.
2. The pH sensors were used for the studies as follows : (1) The acid-base equilibria in gamma-butyrolactone were successfully studies with both types of pH-ISFETs. The same study was impossible with the glass electrode, because gamma-butyrolactone was somewhat decomposed in the course of measurements. (2) The solvolysis and the hydroxide formation of alkaline earth metal ions were studied in some solvents by pH titrations with the iridium electrode. (3) The transfer activity coefficient of proton between various solvents were determined with the pH-ISFETs.