Examination of Pretreatment Conditions (2) Dependency on Quantity of Eluent

In the column switching method, using acetaminophen (a hydrophilic drug), we investigated the influence of switching time of the analysis. The flow rate in the pretreatment column was fixed (0.5mL/min). The switching time was changed from 5 to 20 minutes. Since drugs are absorbed to MSpak PK-2A with the hydrophobic interaction, the adsorption of Hydrophilic drugs to PK-2A is weak. Please be careful of the timing which changes the valve.
Please refer to System diagram.



Sample : 2.5ppm Acetaminophen, 100micro-L

Pretreatment
Column       : Shodex MSpak PK-2A (2.0mmID*10mm)
Eluent       : 10mM CH3COONH4(pH7.0)
Flow rate    : 0.5mL/min
Column temp. : Room temp.
 
Analysis 
Column       : Shodex MSpak GF-4A (4.6mmID*10mm) x 2
Eluent       : 10mM CH3COONH4(pH7.0)/CH3CN=85/15
Flow rate    : 0.3mL/min
Detector     : UV(254nm)
Column temp. : Room temp.