<p>Does anybody have experience measuring DHA and glycerol by UPLC MS? </p>


  • I've used UPLC-ELSD for this type of application.  In a clean matrix, glycerol can be measured using ELSD with a HILIC type column, BEH Amide or Prevail Carbohydrate ES (WR Grace) column, drift tube temp=35C, nebulizer=cooling, 50psi, flow rate=0.5-1.5mL/min (depending on column/particle dimensions), column temp=60C+ (BEH Amide) or 60C (Prevail).   I use isocratic 75:25 acetonitrile:water with 0.2% triethylamine.   The glycerol elution time is just after the solvent front.   If the matrix is dirty, you would need to adjust the mobile phase/flow rate to increase retention. 

    I use a straight silica (monolithic) column under normal phase conditions (isooctane/ipa/water ternary gradient) to monitor FFA content.   However, there is no selectivity with this method, as you will obtain only one peak containing all FFAs.   A diol column should also work.