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生理溶液内氨的浓度常用氨空气隙微电极测定,其检测机理是:氨扩散通过空气隙进入电极尖端内,使局部范围内溶液的pH发生变化。我们设计了一种新的、易于制作的氨气敏微电极,其尖端直径为2—5μm,适合于细胞內记录用。该电极利用硅橡胶憎水膜代替空气隙,并用中性载体离子交换剂作内pH敏感电极,在铵浓度2.0×10~(-4)～2.0×10~(-2)范围内具有良好的线性响应,其斜率为76—80mV/10倍,检测限为10~(-4)M。当测定溶液中铵的总浓度为10~(-3)M时,电极的动力学响应时间为2—3分钟。电极的寿命在一周以上。细胞水平的生物、医学电化学研究对氨微电极的研制及应用显示了日益增长的兴趣与要求。C.P.Pui及G.A.雷克尼兹等研制了第一支氨空气隙气敏微电极。该微电极用pH玻璃电极为内敏感电极,需由四支玻璃微电极管套迭而成,因此,要求难度极大的组装及封接技术。电极的寿命只有一、二天。最近,J.P约瑟夫对上述氨微电极进行了改进性的研究。他使用锑pH微电极为内pH敏感电极,使氨空气隙气敏微电极的寿命增长至一周,组成电极的玻璃管减少成3支,但该电极仍不可避免难度极大的尖端封接过程,因此,电极的实际应用仍然受到限制。本文介绍一种结构简单、制作较为方便、以硅橡胶为憎水膜、中性载体离子交换剂pH微电极为内敏感电极的氨气敏膜微电极。
Ammonia concentration in physiological solution commonly used ammonia air gap microelectrode determination, the detection mechanism is: ammonia diffusion through the air gap into the electrode tip, the local scope of the solution pH changes. We designed a new, easy-to-manufacture ammonia-gas microelectrode with a tip diameter of 2-5 μm, suitable for intracellular recording. The electrode uses the hydrophobic membrane of silicon rubber instead of the air gap and uses the neutral carrier ion exchanger as the internal pH sensitive electrode. It has a good performance in the range of 2.0 × 10 -4 to 2.0 × 10 -2 Linear response, the slope of 76-80mV / 10 times the detection limit of 10 ~ (-4) M. When the total concentration of ammonium in the solution was determined to be 10 ~ (-3) M, the kinetic response time of the electrode was 2-3 minutes. Electrode life in more than a week. Cell-level biology, medical electrochemical research on the development and application of ammonia microelectrodes showed growing interest and requirements. C.P.Pui and G.A. Recknez invented the first ammonia air gap gas sensing microelectrode. The micro-electrode uses a pH glass electrode as an inner-sensitive electrode and needs to be surrounded by four glass micro-electrode tubes. Therefore, the assembly and sealing techniques are extremely difficult. The life of the electrode is only one or two days. Recently, J.P. Joseph on the ammonia microelectrode improved research. He used the antimony pH microelectrode as the internal pH-sensitive electrode to increase the lifetime of the ammonia air gap gas-sensing microelectrode to one week and reduce the number of glass tubes that make up the electrode to three, which is still notoriously difficult to seal , So the practical application of the electrode is still limited. This paper presents an ammonia-sensitive membrane microelectrode with simple structure, more convenient manufacture, silicone rubber as hydrophobic membrane and neutral carrier ion exchanger pH microelectrode as internal sensitive electrode.