A volume of 500 µL aliquot of desloratidine and 3-OH
desloratidine spiked human plasma sample was mixed with 50 µL
of internal standard working solution (50 ng/mL & 30 ng/mL of
desloratidine D5 and 3-OH desloratidine D4 respectively). An
equal volume of 2% Ortho-Phosphoric acid was added and
vortexed to mix. Sample mixture was loaded onto a Strata-X (1
cm3/30 mg), extraction cartridge which was pre-conditioned with
1 mL methanol and equilibrated by 1 mL water. The extraction
cartridge was washed with 1 mL water followed by 1 mL of 20%
methanol in water. Desloratidine and 3-OH desloratidine were
eluted with 1 mL of elution solution (Acetonitrile: Methanol: 10
mM-Ammonium acetate (pH~3.50)-45:45:10 (v/v/v) under low
pressure