Identification and quantitation of trace impurities in fatty alcohol ethoxylates using HPLC and MALDI-TOF mass spectrometry.

A two-step HPLC separation that combines isocratic and gradient elution has been developed for the analysis of trace impurities in fatty alcohol ethoxylates (FAEs). Quantitative estimates of the early eluting impurities were obtained from a calibration curve based on the responses of an evaporative light scattering detector (ELSD). Isocratic conditions were used to elute the impurities and gradient conditions for the main FAE components. In this manner, an acceptable compromise was obtained between resolution and analysis time. Fractions were collected and the impurities identified using MALDI-TOF mass spectrometry.