Applications of Ion Chromatography in the Detergent and Household Product Industry
Detergents for household and industrial use consist of a large number of very dissimilar individual components. As a result of technical developments, and in response to ecological restrictions, these products are constantly changing. Thus, it is not surprising that the respective analytical methods are also under continuous development. Ion chromatography (IC) can be used for the analysis of ionic components in detergents including surfactants, builders, bleaching agents, and fillers, which play a key role in the washing process.
Surfactants are the most important group of detergent components, which were analyzed in the past by a two-phase titration. Today, the analysis of ionic surfactants can be achieved using either ion-pair liquid chromatography in combination with conductivity or UV detection or, more recently, with mixed-mode liquid chromatography coupled with conductivity, UV, or charged aerosol detection. Builders include complexing agents such as polyphosphates or polyphosphonates, ion exchangers such as Zeolith A, and washing alkalines such as sodium carbonate and sodium silicate. For many years, sequestering agents are analyzed by anion-exchange chromatography with an acid eluent and detected by UV after post-column derivatization. Perborate, used for the peroxide bleach, is analyzed by ion-exclusion chromatography with suppressed conductivity detection. Powdered detergents usually contain sodium sulfate as a filler, while liquid detergents and cleaners typically employ short-chain alkylbenzene sulfonates as a finishing material. Because conventional RPLC fails to retain those hydrotropes, bimodal mixed-mode LC columns provide adequate retention for this type of compounds.
Household products and industrial cleansing agents usually contain, besides surfactants, low-molecular weight organic acids and amines, which can be separated by anion- or cation-exchange chromatography, respectively. Condensed inorganic phosphates are usually a constituent of dishwashing agents and can be analyzed by gradient anion-exchange chromatography with suppressed conductivity detection. A characteristic example in the field of cosmetics is the analysis of surfactants in shampoos, which contain various combinations of ionic and nonionic surfactants. Laurylether sulfates and alkylbenzene sulfonates are the most common anionic surfactants used in shampoos, which are separated by either ion-pair or mixed-mode liquid chromatography in combination with nonsuppressed conductivity or UV detection. Inorganic constituents in toothpaste such as monofluorophosphate is another common IC application utilizing anion-exchange chromatography under isocratic conditions.
Presenter: Joachim Weiss (Technical Director, Thermo Fisher Scientific)
Dr. Joachim Weiss started his professional career in 1982 as an applications chemist at Dionex Corporation in Germany. He currently holds the position of International Technical Director for the chromatography commercial organization at Thermo Fisher Scientific. He is renowned for his exceptional knowledge in separation science and is a recognized authority on Thermo Scientific™ IC and HPLC instrumentation and applications.
