变价态唐松草新碱—PVC膜离子选择电极的研制及解离常数的测定

马宛龙; 顾学裘; 苏德森

变价态唐松草新碱—PVC膜离子选择电极的研制及解离常数的测定

PREPARATION OF THE VARIABLE-VALENCY THALIDASINE(TD) PVC MEMBRANE SELECTIVE ELECTRODE AND ITS APPLICATION IN THE pKa DETERMINATION OF THALIDASINE

WL Ma,
XO Gu , DS Su,

摘要

摘要: 本文研制了以四苯硼—唐松草新碱缔合物为电活性物质的变价态唐松草新碱—PVC膜电极。电极膜按电活性物质:PVC:DBP为1:8:8组成。该电极在pH 5.0～6.0,Ⅰ=0.05的NaCl—HCl溶液中Nernst响应范围为1×10^-3～1×10^-5mol/L。电极斜率为58.2 mV/logc。检测限为2.5×10^-6mol/L。用直接电位法考察了TDH⁺,TDH₂CF⁺⁺共存时溶液pH和电极斜率S的关系。用S—pH关系,测定了25℃,Ⅰ=0.05时的Ka₁值为(2.5±0.2)×10^-4,用E—pH关系,测定了25℃,Ⅰ=0.05时的Ka₂值为(8.1±0.9)×10^-8。

Abstract: The construction and performance characteristics of a new variable-valency TD-PVC selective electrode was described. It is based on the TPB. TD ion-pair complex, which was used as electro-active material. The electrode membrane was composed of the complex, PVC and DBP in the ratio of 1:8:8 (w/w/w). The electrode showed Nernstian response from 10^-3 to 10^-5 mol/L in NaCl—HC1 (I=0.05) solution over pH range of 5.0 to 6.0 with a slope of 58.2 mV/pC. The detection limit was found to be 2.5×10^-5 mol/L. The electrode response was quite fast and stable, and the slopes of calibration curves were quite reproducible.It was observed that the E-pC relation can not be simply described by Nernstian equation over wide pH range. The slopes of electrode response and electrode potentials varied in concordance with pH value of the solution. By using the S-pH relation, the Ka₁ was found to be (2.5±0.2)×10^-4. (25℃, I=0.05). Accordingly, Ka₂ was found to be (8.1±0.9)×10^-8(25℃, I=0.05) by using E-pH relation.

HTML全文

参考文献(0)

施引文献

资源附件(0)