Analysis of fatty alcohol derivatives with comprehensive two-dimensional liquid chromatography coupled with mass spectrometry

A simultaneous separation of anionic (fatty alcohol sulfates, fatty alcohol ether sulfates), non-ionic (alkyl polyglucosides, fatty alcohol ethoxylates) and amphoteric (cocamidopropyl betaines) surfactants was performed by comprehensive two-dimensional liquid chromatography (LCxLC) utilizing a ZIC®-HILIC column in the first dimension, a Reprosphere 100 C8-Aqua column in the second dimension and a 10-port two position valve as the interface. The volume of the two sample loops were 25 or 50 μL and allow a one or two minute modulation at a 25 μL/min flow rate. In the first dimension, a gradient of acetonitrile and an ammonium acetate buffer was used to separate polyethoxylated surfactants by their degree of ethoxylation (EO number) whereas in the second dimension, a separation by alkyl chain was performed using a methanol/ammonium acetate buffer gradient. A baseline separation of the above mentioned surfactants according to both EO number and alkyl chain was achieved. The best performance was used to compare two different LCxLC–QTOF MS systems, which demonstrate that a transfer of the method from one system to a totally different system is possible. However, because of the differences in delay volume and extra-column volume between these systems the separation power is changed.