Analytical Sciences

Use of Relative Molar Sensitivity as a Specific Value for Evaluating Heptaoxyethylene Dodecyl Ether Concentrations in Methanol Solution

Miho KUROE,* Masahiko NUMATA,* Naoko MASUMOTO,** Yuzo NISHIZAKI,** Naoki SUGIMOTO,** and Nobuyasu ITOH*

*Research Institute for Material and Chemical Measurement, National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan
**Division of Food Additives, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki, Kawasaki, Kanagawa 210-9501, Japan

Relative molar sensitivity (RMS) determined using quantitative ¹H NMR and HPLC with a refractive index (RI) detector was applied as a specific value for quantifying the levels of heptaoxyethylene dodecyl ether (HOEDE), a typical non-ionic surfactant, in methanol solutions. RMS was robust against changes of the analytical conditions (i.e., RI cell temperature, acetonitrile content in the mobile phase, HPLC system). Furthermore, the obtained HOEDE concentrations using a previously evaluated RMS were comparable to those obtained using a reference method for over 1 year.

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