Basic Drugs : Under Neutral Condition

Elution patterns of four kinds of basic drugs which have tertiary amine are shown. Under the eluent conditions, large peak tailing and delay of elution are observed for ODS-A and ODS-B except scopolamine. To the contrary, the elution patterns of ODS-C (polymer-coated) and ODP (polymer-based) for procainamide and atropine are far better than those of ODS-A and ODS-B though peak tailing is observed for diphenhydramine. These chromatograms show non-specific adsorption which is usually observed for Asahipak ODP columns and its solution using polymer-based or polymer-coated columns.

Sample :
1.0mg/mL Scopolamine hydrochloride, 50micro-L
1.0mg/mLProcainamide hydrochloride, 40micro-L
0.5mg/mLDiphenhydramine hydrochloride, 2micro-L
1.0mg/mLAtropine, 50micro-L

 Columns : Shodex Asahipak ODP-50 4D (4.6mmID*150mm), 
 ODS-A, ODS-B, ODS-C (4.6mmID*150mm each)
 Eluent : 25mM Phosphate buffer(pH7)/CH3CN=60/40
 Flow rate : 0.6mL/min
 Detector : UV(254nm)
 Column temp. : 30°C