Analytical Sciences
Online ISSN : 1348-2246
Print ISSN : 0910-6340
ISSN-L : 0910-6340
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Potentiometric Titration of Polyhexamethylene Biguanide Hydrochloride with Potassium Poly(vinyl sulfate) Solution Using a Cationic Surfactant-selective Electrode
Takashi MASADOMEYuichi YAMAGISHIMasaki TAKANOToshiaki HATTORI
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2008 Volume 24 Issue 3 Pages 415-418

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Abstract

A potentiometric titration method using a cationic surfactant as an indicator cation and a plasticized poly(vinyl chloride) membrane electrode sensitive to the cationic surfactant is proposed for the determination of polyhexamethylene biguanide hydrochloride (PHMB-HCl), which is a cationic polyelectrolyte. A sample solution of PHMB-HCl containing an indicator cation (hexadecyltrimethylammonium ion, HTA) was titrated with a standard solution of an anionic polyelectrolyte, potassium poly(vinyl sulfate) (PVSK). The end-point was detected as a sharp potential change due to an abrupt decrease in the concentration of the indicator cation, HTA, which is caused by its association with PVSK. The effects of the concentrations of HTA ion and coexisting electrolytes in the sample solution on the degree of the potential change at the end-point were examined. A linear relationship between the concentration of PHMB-HCl and the end-point volume of the titrant exists in the concentration range from 2.0 × 10-5 to 4.0 × 10-4 M in the case that the concentration of HTA is 1.0 × 10-5 M, and that from 1.0 × 10-6 to 1.2 × 10-5 M in the case that the concentration of HTA is 5.0 × 10-6 M, respectively. The proposed method was applied to the determination of PHMB-HCl in some contact-lens detergents.

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© 2008 by The Japan Society for Analytical Chemistry
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