Bis[2-(5-bromo-2-pyridylazo)-5-( N-propyl- N-sulpho propylamino)phenolato]cobaltate(III) as a counter ion for the extraction and spectrophotometric determination of long-chain quaternary ammonium salts and tertiary alkylamines in the presence of each other

• Published in: Analytica chimica acta 1989, Vol.219 (2), p.239-245
• Main Authors: Kasahara, Issei, Kanai, Masami, Taniguchi, Masako, Kakeba, Ayako, Hata, Noriko, Taguchi, Shigeru, Goto, Katsumi
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Chemistry; Exact sciences and technology; Spectrometric and optical methods
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/S0003-2670(00)80355-4

The singly charged complex anion bis[2-(5-bromo-2-pyridylazo)-5-( N-propyl- N-sulphopropylamino)phenolato]cobaltate(III) is intensely purple-violet and is stable over the pH range 1–13. Its absorption spectrum remains the same over this pH range. At pH2, it forms extractable ion pairs with long-chain quaternary ammonium ions and protonated alkylamines. Only the quaternary ammonium ions are extracted into chloroform at pH 11, hence separate extractions allow both types to be determined. The absorbance of the organic phase is measured at 594 nm. The apparent molar absorptivity is 7.0 × 10 4 l mol −1 cm −1. Calibration graphs for zephiramine, benzethonium and hexadecylpyridinium ions are linear over the range 0.1–2 × 10 −6 M. The only interference found was from anionic surfactants. The method is applied to hair and fabric conditioners.