<正> In this Paper, PVC membrane Selective clectrodes are prepared for theophylline which are based on its ion-pair complexes with hexadecylt- rioctylammonium iodide (HTOA) , hexadecyltributyl-ammonium iodide (H...<正> In this Paper, PVC membrane Selective clectrodes are prepared for theophylline which are based on its ion-pair complexes with hexadecylt- rioctylammonium iodide (HTOA) , hexadecyltributyl-ammonium iodide (HTBA), hexadeeyltriophenylphosphonium iodide(HTPP), triphenyloctylphosphonium leoide(TPOP) and tri(p-tolyl) butylphosphonium iodide(TPTBP).The effects of the nature of associate counterions, the plastieizers and their concentrations in the membrane phase have been studied. The electrode based on theophylline-HTOA membrane has a sub-Nernstian response range from 2.0×10~2—6.3×10~(-5)mol/L,with an average slope of 48.0mV/pC. The limit of detection is 8.7×10~(-6)mol/L. The electrode responses were not affected by pH in the range 10-12. The potentiometric selectivity coefficients of various common inorganic and organic ions including those which are similar to theophylline in structure were determined. The Na_2CO_3-Na_2B_4O_7 buffer of pH 11 is selected as the background solution for potentiometric measurements. The electrode was used for determining the theophylline in pharmaceutical preparations with satisfactory results.展开更多
In this paper three air and water-stable room temperature ionic liquids(RTILs): N-butylpyridinium tetrafluoroborate(BPBF 4), 1-butyl-3-methylimidazolium tetrafluoroborate(BMIBF 4), and 1-ethyl-3-methylimidazolium ethy...In this paper three air and water-stable room temperature ionic liquids(RTILs): N-butylpyridinium tetrafluoroborate(BPBF 4), 1-butyl-3-methylimidazolium tetrafluoroborate(BMIBF 4), and 1-ethyl-3-methylimidazolium ethyl sulfate(EMISE) were synthesized. Their electrochemical windows were measured by cyclic voltammetry at 303.15-343.15 K. The cyclic voltammograms show the order of windows which represent the electrochemical stability of RTIL is: BPBF 4<BMIBF 4<EMISE. When temperature increases the windows reduce, that is, the stability of RTIL reduces with the increase of temperature. The difference among the windows of the three RTILs is mainly dependent on the order of the reductive limits of the cations: EMI+--1.40 V->BMI+--0.95 V->BP+-0.02 V-. It is very interesting that while the oxidative limit of anion BF- 4 and the reductive limit of all the cations reduce with the increase of temperature, but the oxidative limit of anion SE- increases.展开更多
文摘<正> In this Paper, PVC membrane Selective clectrodes are prepared for theophylline which are based on its ion-pair complexes with hexadecylt- rioctylammonium iodide (HTOA) , hexadecyltributyl-ammonium iodide (HTBA), hexadeeyltriophenylphosphonium iodide(HTPP), triphenyloctylphosphonium leoide(TPOP) and tri(p-tolyl) butylphosphonium iodide(TPTBP).The effects of the nature of associate counterions, the plastieizers and their concentrations in the membrane phase have been studied. The electrode based on theophylline-HTOA membrane has a sub-Nernstian response range from 2.0×10~2—6.3×10~(-5)mol/L,with an average slope of 48.0mV/pC. The limit of detection is 8.7×10~(-6)mol/L. The electrode responses were not affected by pH in the range 10-12. The potentiometric selectivity coefficients of various common inorganic and organic ions including those which are similar to theophylline in structure were determined. The Na_2CO_3-Na_2B_4O_7 buffer of pH 11 is selected as the background solution for potentiometric measurements. The electrode was used for determining the theophylline in pharmaceutical preparations with satisfactory results.
文摘In this paper three air and water-stable room temperature ionic liquids(RTILs): N-butylpyridinium tetrafluoroborate(BPBF 4), 1-butyl-3-methylimidazolium tetrafluoroborate(BMIBF 4), and 1-ethyl-3-methylimidazolium ethyl sulfate(EMISE) were synthesized. Their electrochemical windows were measured by cyclic voltammetry at 303.15-343.15 K. The cyclic voltammograms show the order of windows which represent the electrochemical stability of RTIL is: BPBF 4<BMIBF 4<EMISE. When temperature increases the windows reduce, that is, the stability of RTIL reduces with the increase of temperature. The difference among the windows of the three RTILs is mainly dependent on the order of the reductive limits of the cations: EMI+--1.40 V->BMI+--0.95 V->BP+-0.02 V-. It is very interesting that while the oxidative limit of anion BF- 4 and the reductive limit of all the cations reduce with the increase of temperature, but the oxidative limit of anion SE- increases.
