LC/MS is effective for the high sensitivity analysis of drugs; however, when protein is present and enters the MS (Mass Detector), it contaminates the MS or suppresses ionization of the sample. Pretreatment does not often remove protein thoroughly. Drugs in biological fluid are hard to analyze because protein co-elutes with the component of interest. The target drug receives ion suppression from the protein and appears as a small peak. ODP2 HP can separate the target from protein by eluting protein early and clearly. Barbital was introduced into the MS by a switching valve after BSA (protein) was eluted, and barbital was detected without any influence of ion suppression.


Sample : Barbital (500 ng/mL) in BSA (7.0 mg/L), 10 μL

Column       : Shodex ODP2 HP-2B (2.0 mm I.D. x 50 mm)
Eluent       : 10 mM Ammonium acetate aq./CH3CN=70/30
Flow rate    : 0.2 mL/min
Detector     : UV (280 nm), ESI-MS (SIM negative)
Column temp. : 30 °C