A K^+-selective electrode and a Na^+-selective electrode were used to construct a measuring cell without liquid-junction for the determination of the ion activity ratio of K^+ to Na^+ in soil suspensions.The measured...A K^+-selective electrode and a Na^+-selective electrode were used to construct a measuring cell without liquid-junction for the determination of the ion activity ratio of K^+ to Na^+ in soil suspensions.The measured cell potential was not affected by the total electrolyte concentration when the total cation concentration was 10^-1-10^-3 mol L^-1 and the concentration ratio Ck+/CNa+ was 10:1 to 1:50.When the concentration ratios were equal to 1 and the total electrolyte concentrations were 10^-2 and 10^-3 mol L^-1,the ion activity ratio measurenent would not be affected by pH in the pH range of 3.5 to 11.5 and 4.4 to 11 respectively.Ions other than H^+ have no remarkable influence on the measurement.The ion activity ratio of K^+ to Na^+ measured directly in soil suspension agree well with those in centrifuged supernant solution.The relative deviation was within 4%.From the measured ion activity ratio,the difference of the bonding energies of K^+ and Na^+ ions was calculated.展开更多
Interactions of potassium and calcium ions with four typical variable charge soils in South China were examined by measuring pK-0.5pCa value with a potassium ion-selective electrode and a calcium ion-selective electro...Interactions of potassium and calcium ions with four typical variable charge soils in South China were examined by measuring pK-0.5pCa value with a potassium ion-selective electrode and a calcium ion-selective electrode,and pK value with a potassium ion-selective electrode.The results showed that adsorption of potassium and calcium ions increased with soil suspension pH,and the tendency of the pK-0.5pCa value changing with pH differed with respect to pH range and potassium to calcium ratio.Adsorption of equal amount of calcium and potassium ions led to release of an identical number of protons,suggesting similar adsorption characteristics of these two ions when adsorbed by variable charge soils.Compared with red soil,latosol and lateritic red soil had higher adsorption selectivities for calcium ion.The red soil had a greater affinity for potassium ion than that for calcium ion at low concentration,which seems to result from its possession of 2:1 type minerals,such as vermiculite and mica with a high affinity for potassium ion.The results indicated that adsorption of potassium and calcium ions by the variable charge soils was chiefly caused by the electrostatic attraction between the cations and the soil surfaces.Moreover,it was found that sulfate could affect the adsorption by changing soil surface properties and by forming ion-pair.展开更多
A new chemically modified carbon paste electrode for cesium(I) ion determination based on potassium zinc hexacyan-oferrate (PZHCF) as an ionophore was prepared. The electrode exhibits a Nernstian response for Cs(I) io...A new chemically modified carbon paste electrode for cesium(I) ion determination based on potassium zinc hexacyan-oferrate (PZHCF) as an ionophore was prepared. The electrode exhibits a Nernstian response for Cs(I) ions over a wide concentration range from 1 × 10-6 to 1 × 10-1 mol·L-1 with a slope of 58 ± 0.5 mV·decade-1. It has a response time of about 35 s and can be used for a period of 3 months with good reproducibility. Detection limit obtained in the optimal conditions was 3 × 10-7 mol·L-1. The potentiometric response is independent of the pH of the solution in the pH range 4.0 - 8.0. The electrode possesses the advantages of low resistance, fast response over a variety of other cations. The proposed electrode is applied as a sensor for the determination of Cs(I) ion concentration in different samples solutions. The results showed a good correlation with the data obtained by atomic absorption spectrometric method.展开更多
Novel potassium ion selective electrodes (K^+ISEs) and cDNA array sensors based on porous silicon (PS) have been developed.The calibration curve for the K^+ISEs is linear within a wide range of pK=2.0～6.0 with the sl...Novel potassium ion selective electrodes (K^+ISEs) and cDNA array sensors based on porous silicon (PS) have been developed.The calibration curve for the K^+ISEs is linear within a wide range of pK=2.0～6.0 with the slope of 56 mV per decade,which is near Nernst response.The response time and detection limit are within 31 s and 0.5μmol/L,respectively.The selective coefficient for Na^+ is-3.8,satisfies the requirement for the assay of blood potassium.The response variation is within 2 mV during 2 months.The binding capacity,the dynamic range and the detection limit of the DNA sensors were improved by replacing glass slide with PS substrates.The cDNA array sensors can bear 80℃of high temperature,75% of humidity,3.6 kLx of irradiation and keep stable within 10 days when they are exposed in air.Good performances of the K^+ISE and the cDNA array sensor are attributed to the large internal surface area and the easily modified microstructure of PS.展开更多
文摘A K^+-selective electrode and a Na^+-selective electrode were used to construct a measuring cell without liquid-junction for the determination of the ion activity ratio of K^+ to Na^+ in soil suspensions.The measured cell potential was not affected by the total electrolyte concentration when the total cation concentration was 10^-1-10^-3 mol L^-1 and the concentration ratio Ck+/CNa+ was 10:1 to 1:50.When the concentration ratios were equal to 1 and the total electrolyte concentrations were 10^-2 and 10^-3 mol L^-1,the ion activity ratio measurenent would not be affected by pH in the pH range of 3.5 to 11.5 and 4.4 to 11 respectively.Ions other than H^+ have no remarkable influence on the measurement.The ion activity ratio of K^+ to Na^+ measured directly in soil suspension agree well with those in centrifuged supernant solution.The relative deviation was within 4%.From the measured ion activity ratio,the difference of the bonding energies of K^+ and Na^+ ions was calculated.
文摘Interactions of potassium and calcium ions with four typical variable charge soils in South China were examined by measuring pK-0.5pCa value with a potassium ion-selective electrode and a calcium ion-selective electrode,and pK value with a potassium ion-selective electrode.The results showed that adsorption of potassium and calcium ions increased with soil suspension pH,and the tendency of the pK-0.5pCa value changing with pH differed with respect to pH range and potassium to calcium ratio.Adsorption of equal amount of calcium and potassium ions led to release of an identical number of protons,suggesting similar adsorption characteristics of these two ions when adsorbed by variable charge soils.Compared with red soil,latosol and lateritic red soil had higher adsorption selectivities for calcium ion.The red soil had a greater affinity for potassium ion than that for calcium ion at low concentration,which seems to result from its possession of 2:1 type minerals,such as vermiculite and mica with a high affinity for potassium ion.The results indicated that adsorption of potassium and calcium ions by the variable charge soils was chiefly caused by the electrostatic attraction between the cations and the soil surfaces.Moreover,it was found that sulfate could affect the adsorption by changing soil surface properties and by forming ion-pair.
文摘A new chemically modified carbon paste electrode for cesium(I) ion determination based on potassium zinc hexacyan-oferrate (PZHCF) as an ionophore was prepared. The electrode exhibits a Nernstian response for Cs(I) ions over a wide concentration range from 1 × 10-6 to 1 × 10-1 mol·L-1 with a slope of 58 ± 0.5 mV·decade-1. It has a response time of about 35 s and can be used for a period of 3 months with good reproducibility. Detection limit obtained in the optimal conditions was 3 × 10-7 mol·L-1. The potentiometric response is independent of the pH of the solution in the pH range 4.0 - 8.0. The electrode possesses the advantages of low resistance, fast response over a variety of other cations. The proposed electrode is applied as a sensor for the determination of Cs(I) ion concentration in different samples solutions. The results showed a good correlation with the data obtained by atomic absorption spectrometric method.
基金supported by National Natural Science Foundation of China(69925409,60276036)Shanghai Applied Material Foundation(0202).
文摘Novel potassium ion selective electrodes (K^+ISEs) and cDNA array sensors based on porous silicon (PS) have been developed.The calibration curve for the K^+ISEs is linear within a wide range of pK=2.0～6.0 with the slope of 56 mV per decade,which is near Nernst response.The response time and detection limit are within 31 s and 0.5μmol/L,respectively.The selective coefficient for Na^+ is-3.8,satisfies the requirement for the assay of blood potassium.The response variation is within 2 mV during 2 months.The binding capacity,the dynamic range and the detection limit of the DNA sensors were improved by replacing glass slide with PS substrates.The cDNA array sensors can bear 80℃of high temperature,75% of humidity,3.6 kLx of irradiation and keep stable within 10 days when they are exposed in air.Good performances of the K^+ISE and the cDNA array sensor are attributed to the large internal surface area and the easily modified microstructure of PS.
