Comparisons of Two Separation Modes on Saturated Fatty Acid LC/MS Analysis (C18U 2D, VT-50 2D)

Fatty acids are compounds where a hydrocarbon chain is attached to a carboxyl group. They can be classified into saturated fatty acids (having no double bonds between carbons) and unsaturated fatty acids (having double bonds). In this application, eight saturated fatty acids with alkyl chains ranging from C6 to C13 were analyzed using a UHPLC compatible ODS column, C18U 2D, and a polymer-based HILIC mode column, HILICpak VT-50 2D. Their separation patterns were compared. Under a reverse phase mode (C18U 2D), longer-chain fatty acids are retained longer. Whereas quaternary ammonium functional group modified on VT-50 2D packing material creates ion-exchange interactions, resulting in stronger retention for shorter-chain fatty acids.

Note:
Fatty acids with more than 14 carbon chain have low solubility in water and acetonitrile, thus their analysis under the mentioned condition is not recommended.
Refer to "Solubility of Saturated Fatty Acids"

Sample: 10 μL
50 ng/mL each  (in CH3OH/H2O=1/1)

  1. C13; Tridecylic acid
  2. C12; Lauric acid
  3. C11; Undecylic acid
  4. C10; Capric acid
  5. C9; Pelargonic acid
  6. C8; Caprylic acid
  7. C7; Enanthic acid
  8. C6; Caproic acid
Chromatogram of fatty acids_C18U 2D
Chromatogram of fatty acids_VT-50 2D
Column
：Shodex C18U 2D (2.0 mm I.D. x 150 mm)
Eluent
：20 mM CH3COONH4 aq./CH3CN=50/50
Flow rate
：0.2 mL/min
Detector
：ESI-MS (SIM Negative)
Column temp.
：40 ℃
 
Column
：Shodex HILICpak VT-50 2D (2.0 mm I.D. x 150 mm)
Eluent
：50 mM CH3COONH4 aq./CH3CN=30/70
Flow rate
：0.2 mL/min
Detector
：ESI-MS (SIM Negative)
Column temp.
：40 ℃

Sample Name Index

Operation Manual / Certificate of Analysis

Operation Manuals and Certificate of Analysis / Inspection Certificate for the following products can be downloaded here.

Product Name Index

Applications