Determination of polyhexamethylene biguanide hydrochloride using photometric colloidal titration with crystal violet as a color indicator

Takashi Masadome, Takaaki Miyanishi, Keita Watanabe, Hiroshi Ueda, Toshiaki Hattori

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Abstract

A solution of polyhexamethylene biguanide hydrochloride (PHMB-HCl) was titrated with a standard solution of potassium poly(vinyl sulfate) (PVSK) using crystal violet (CV) as an photometric indicator cation. The end point was detected by a sharp absorbance change due to an abrupt decrease in the concentration of CV. A linear relationship between the concentration of PHMB-HCl and the end-point volume of the titrant existed in the concentration range from 2 to 10 × 10 -6 eq mol L -1 . Back-titration was based on adding an excess amount of PVSK to a sample solution containing CV, which was titrated with a standard solution of poly(diallyldimethylammonium chloride) (PDADMAC). The calibration curve of the PHMB-HCl concentration to the end point volume of the titrant was also linear in the concentration range from 2 to 8 × 10 -6 eq mol L -1 . Both photometric titrations were applied to the determination of PHMB-HCl in a few contact-lens detergents. Back-titration showed a clear end point, but direct titration showed an unclear end point. The results of the back-titration of PHMB-HCl were compared with the content registered in its labels.

Original languageEnglish
Pages (from-to)817-821
Number of pages5
JournalAnalytical Sciences
Volume27
Issue number8
DOIs
Publication statusPublished - 2011

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ASJC Scopus subject areas

  • Analytical Chemistry

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