High pressure liquid chromatography

Agilent 1100 Series HPLC & ThermoFisher LCQ™ DECA XP

For the analysis of thermally labile, polar or high molecular mass compounds that are not readily analysed using GC-MS, we use a High Pressure Liquid Chromatograph (Agilent 1100 Series capillary system) coupled to an ion trap mass spectrometer (Thermo LCQ™ DECA XP). Compound classes analysed at RSES include hopanepolyols, phospholipids and other intact polar lipids (ILPs), carotenoids, porphyrins and archaeols.

The HPLC system separates complex molecular mixtures by pumping a solution under high pressure through a capillary column packed with an active phase specifically selected to optimize separation of desired analytes. The separated analytes are then delivered to the mass spectrometer where they are ionized and accelerated into the Ion Trap mass analyzer.

The LCQ™ DECA XP at RSES has two atmospheric pressure ionization modes

  1. Electrospray ionization (ESI)
  2. Atmospheric pressure chemical ionization (APCI)

Both methodologies are soft ionization techniques, i.e. they produce predominantly protonated molecular ions (MH+) and, thus, allow determination of molecular weights. However, both the ESI and APCI probes can run in positive and negative ion modes, yielding complementary structural information.

Experiments that can be performed on above system

  1. General MS or MSn - used for detection and quantitative analysis of known compounds
  2. Data dependent - used for qualitative analysis of unknown compounds for structure elucidation or confirmation
  3. Ion mapping - allows full structural characterization of unknown molecules in complex mixtures
  4. Ion Tree Experiments - automatic collection of MSn data