Journal of Surfactants and Detergents

, Volume 2, Issue 4, pp 503–513 | Cite as

Analysis of ethoxylated fatty amines. Comparison of methods for the determination of molecular weight

  • Russell F. Lang
  • Dennisse Parra-Diaz
  • Dana Jacobs


Specific lengths of the fatty and polyoxyethylene chains of ethoxylated fatty amines are critical to their performance in specific applications, and thus the ability to characterize these surfactants accurately is crucial. Normal-phase high-performance liquid chromatography (HPLC) and matrixassisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry methods were developed to determine with accuracy the molecular weight and degree of ethoxylation of ethoxylated fatty amines. Ethoxylated fatty amines were analyzed using these methods, and comparison was made to molecular weight determinations using proton nuclear magnetic resonance (NMR), neutralization equivalent weight, and hydroxyl value methods. Molecular weight results from normalphase HPLC analyses were in very good agreement with MALDI-TOF results, typically varying less than one ethylene oxide unit. A reversed-phase HPLC method was developed to determine concentrations of polyethylene glycols (PEG) and fatty homologs. PEG interfered with molecular weight determinations by NMR, neutralization equivalent weight, and hydroxyl value methods. PEG caused no interference with molecular weight determinations by normal-phase HPLC and MALDI-TOF methods.

Key Words

Degree of ethoxylation ethoxylated fatty amines HPLC hydroxyl value MALDI-TOF molecular weight neutralization equivalent weight H NMR 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Reck, R., Cationic Surfactants Derived from Nitriles, in Cationic Surfactants, edited by J. Richmond, Surfactant Science Series, Marcel Dekker, Inc., New York, 1990, Vol. 34, p. 163.Google Scholar
  2. 2.
    Cegarra, J., J. Valldeperas, J. Navarro, and A. Navarro, Influence of Oxyethylenated Alkylamines in the Dyeing of Wool, J. Soc. Dyers Colour 99:291 (1983).Google Scholar
  3. 3.
    Tsatsaroni, E., I. Eleftheriadis, and A. Kehayoglou, The Role of Polyoxyethylenated Stearylamines in the Dyeing of Cotton with Direct Dyes, ——Ibid. 106:245 (1990).CrossRefGoogle Scholar
  4. 4.
    Arif, S., Fatty Amine Ethoxylates, HAPPI, 67 (1996).Google Scholar
  5. 5.
    Cross, J., Introduction to Nonionic Surfactants, in Nonionic Surfactants, edited by J. Cross, Surfactant Science Series, Marcel Dekker, Inc., New York, 1987, Vol. 19, p. 3.Google Scholar
  6. 6.
    Miwidsky, B.M., and D.M. Gabriel, Detergent Analysis, 1982, John Wiley & Sons, New York, pp. 207–208.Google Scholar
  7. 7.
    Cross, J., Aspects of Quality and Process Control, in Nonionic Surfactants, edited by J. Cross Surfactant Science Series, Marcel Dekker, Inc., New York, 1987, Vol. 19, p. 371.Google Scholar
  8. 8.
    Marquez, N., R. Anton, A. Usubillaga, and J.L. Salager, Optimization of HPLC Conditions to Analyze Widely Distributed Ethoxylated Alkylphenol Surfactants, J. Liquid Chromatogr. 17:1147 (1994).Google Scholar
  9. 9.
    Miszkiewicz, W., and L. Szymanowski, Analysis of Nonionic Surfactants with Polyoxyethylene Chains by High-Performance Liquid Chromatography, Crit. Rev. Anal. Chem. 25:203 (1996).Google Scholar
  10. 10.
    Ban, T., E. Papp, and J. Inczedy, Reversed-Phase High-Performance Liquid Chromatography of Anionic and Ethoxylated Non-Ionic Surfactants and Pesticides in Liquid Pesticide Formulations. J. Chromatogr. 593:227 (1992).CrossRefGoogle Scholar
  11. 11.
    Zeman, I., J. Silha, and M. Bares, Separation of Ethoxylates by HPLC, Tenside Deterg. 23:181 (1986).Google Scholar
  12. 12.
    Schreuder, R., A. Martin, H. Poppe, and J.C. Kraak, Determination of the Composition of Ethoxylated Alkylamines in Pesticide Formulations by High-Performance Liquid Chromatography Using Ion-Pair Extraction Detection. J. Chromatogr. 368:339 (1986).CrossRefGoogle Scholar
  13. 13.
    Martin, N., Analysis of Non-Ionic Surfactants by HPLC Using Evaporative Light-Scattering Detector. J. Liquid Chromatogr. 18:1173 (1995).Google Scholar
  14. 14.
    Bahr, U., A. Deppe, M. Karas, F. Hillenkamp, and U. Geissmann, Mass Spectrometry of Synthetic Polymers by UV-Matrix-Assisted Laser Desorption/Ionization, Anal. Chem. 64:2866 (1992).CrossRefGoogle Scholar
  15. 15.
    Thomson, B., Z. Wang, A. Paine, A. Rudin, and G., Lajoe, Surfactant Analysis by Matrix-Assisted Laser Desorption Time-of-Flight Mass Spectrometry. J. Am. Oil Chem. Soc. 72:11 (1995).Google Scholar
  16. 16.
    Montaudo, G., M. Montaudo, C. Puglisi, and F. Samperi, Characterization of Polymers by Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry: Molecular Weight Estimates in Samples of Varying Polydispersity. Rapid Commun. Mass Spectrom. 9:453 (1995).CrossRefGoogle Scholar
  17. 17.
    Bartsch, H., M. Strabner, and U. Hintze, Characterization and Identification of Ethoxylated Surfactants by Matrix-Assisted Laser Desoption/Ionization Mass Spectrometry, Tenside Surf. Det. 35:94 (1998).Google Scholar
  18. 18.
    Wu, K., and R. Odom, Characterizing Synthetic Polymers by MALDI MS, Anal. Chem. 70:456A (1998).Google Scholar
  19. 19.
    Montana, A., Nuclear Magnetic Resonance Spectrometry of Nonionic Surfactants, in Nonionic Surfactants, edited by J. Cross, Surfactant Science Series, Vol. 19, Marcel Dekker, Inc., New York, 1987, p. 295.Google Scholar
  20. 20.
    AOCS Hydroxyl Value Determination, Official and Recommended Practices of the American Oil Chemists' Society, AOCS Press, Champaign, 1993, Method Cd 13–60.Google Scholar
  21. 21.
    Snyder, L., J. Glajch, and J. Kirkland, Practical HPLC Method Development, John Wiley & Sons, New York, 1988, pp. 60, 61.Google Scholar
  22. 22.
    Dreux, M., M. Lafosse, and L. Morin-Allory, The Evaporative Light Scattering Detector-A Universal Instrument for Non-Volatile Solutes in LC and SFC, LCGC International 14:148 (1996).Google Scholar

Copyright information

© AOCS Press 1999

Authors and Affiliations

  • Russell F. Lang
    • 1
  • Dennisse Parra-Diaz
    • 1
  • Dana Jacobs
    • 1
  1. 1.Beckman-Coulter Inc.Miami

Personalised recommendations