Phthalates were analyzed using RSpak DS-613 with different eluents. With THF/H2O eluent, the elution pattern is that of typical reversed phase. With C2H5OH eluent, the pattern is also that of reversed phase but the peak shape is rather broad and the separation is not so good except the separation between DEHP and DBP. With n-hexane/C2H5OH eluent, the elution pattern is that of normal phase.

Sample : 2.5micro-L
(A)0.2% each, 0.4%(DOP)
(B)(C)0.4% each
1. DMP, Dimethyl phthalate
2. DEP, Diethyl phthalate
3. DPP, Dipropyl phthalate
4. DBP, Dibutyl phthalate
5. DHP, Dihexyl phthalate
6. DEHP, Diethylhexyl phthalate
7. DOP, Dioctyl phthalate

Column       : Shodex RSpak DS-613 (6.0mmID*150mm)
Eluent       : (A) THF/H2O=70/30 (Reversed phase)
               (B) C2H5OH (Reversed phase)
               (C) n-Hexane/C2H5OH=95/5 (Normal phase)
Flow rate    : (A)0.5mL/min, (B)(C)0.6mL/min
Detector     : UV(254nm)
Column temp. : (A)(B) 50deg-C, (C)25deg-C