Use of Nafion® membranes for the construction of optical sensors for pH measurements

Quimica nova

Raimundo Jr, Ivo M.¹  Pinheiro, Silvia Cristina Lopes¹ 

[1] Universidade Estadual de Campinas, Campinas

关键词: optical sensor;    optode;    pH sensor.;   

DOI  :  10.1590/S0100-40422005000500036

学科分类：化学（综合）

来源: Sociedade Brasileira de Quimica

【 摘 要 】

The behaviour ofNafion® polymeric membranes containing acid-base dyes, bromothymolblue (BB) and methyl violet (MV), were studied aiming at constructing an opticalsensor for pH measurement. BB revealed to be inadequate for developing sensingphases due to the electrostatic repulsion between negative groups of their moleculesand the negative charge of the sulfonate group of the Nafion®,which causes leaching of the dye from the membrane. On the other hand, MV showedto be suitable due to the presence of positive groups in its structure. Themembrane prepared from a methanolic solution whose Nafion®/dyemolar ratio was 20 presented the best analytical properties, changing its colorfrom green to violet in the pH range from 0.6 to 3.0. The membrane can be preparedwith good reproducibility, presenting durability of ca. 6 months and responsetime of 22 s, making possible its use for pH determination in flow analysissystems.

【 授权许可】

CC BY