Analysis of the purity of cetrimide by titrations

Claus D. Rasmussen, Hans B. Nielsen, Jens E T Andersen

    Research output: Contribution to journalArticle

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    Abstract

    The purity of cetrimide, trimethyl tetradecyl ammonium bromide (TTAB), which is an important preservative of many cosmetic and pharmaceutical products, was determined by three independent methods of titration. Traditionally, cetrimide was analysed by an assay method of the European Pharmacopoeia, which showed consistently a low purity of cetrimide with associated large standard deviations, however. A systematic 3% bias of the European Pharmacopoeia assay method was identified by comparing the result with results of two alternative methods of titration that exhibited high precision and high accuracy. Titration by perchloric acid showed a 99.69% ± 0.05% purity of cetrimide, and titration by silver nitrate showed a 99.85% ± 0.05% purity, while the traditional assay method predicted a purity of only 97.1% ± 0.4%. It was found that the discrepancy could be identified as differences in selectivity during the extraction step of the European Pharmacopoeia assay method. The distribution coefficients between chloroform and water of cetrimide and the corresponding iodide species (TTAI) were thus determined as 2150 ± 50 M-1 and 68000 ± 4000 M-1, respectively.

    Original languageEnglish
    Pages (from-to)104-110
    Number of pages7
    JournalPDA Journal of Pharmaceutical Science and Technology
    Volume60
    Issue number2
    Publication statusPublished - Mar 2006

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    Pharmacopoeias
    Silver Nitrate
    Iodides
    Chloroform
    Cosmetics
    cetrimonium
    Water
    Pharmaceutical Preparations

    All Science Journal Classification (ASJC) codes

    • Pharmaceutical Science

    Cite this

    Rasmussen, Claus D. ; Nielsen, Hans B. ; Andersen, Jens E T. / Analysis of the purity of cetrimide by titrations. In: PDA Journal of Pharmaceutical Science and Technology. 2006 ; Vol. 60, No. 2. pp. 104-110.
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    abstract = "The purity of cetrimide, trimethyl tetradecyl ammonium bromide (TTAB), which is an important preservative of many cosmetic and pharmaceutical products, was determined by three independent methods of titration. Traditionally, cetrimide was analysed by an assay method of the European Pharmacopoeia, which showed consistently a low purity of cetrimide with associated large standard deviations, however. A systematic 3{\%} bias of the European Pharmacopoeia assay method was identified by comparing the result with results of two alternative methods of titration that exhibited high precision and high accuracy. Titration by perchloric acid showed a 99.69{\%} ± 0.05{\%} purity of cetrimide, and titration by silver nitrate showed a 99.85{\%} ± 0.05{\%} purity, while the traditional assay method predicted a purity of only 97.1{\%} ± 0.4{\%}. It was found that the discrepancy could be identified as differences in selectivity during the extraction step of the European Pharmacopoeia assay method. The distribution coefficients between chloroform and water of cetrimide and the corresponding iodide species (TTAI) were thus determined as 2150 ± 50 M-1 and 68000 ± 4000 M-1, respectively.",
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    Analysis of the purity of cetrimide by titrations. / Rasmussen, Claus D.; Nielsen, Hans B.; Andersen, Jens E T.

    In: PDA Journal of Pharmaceutical Science and Technology, Vol. 60, No. 2, 03.2006, p. 104-110.

    Research output: Contribution to journalArticle

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