Table I.
Effect of Content of Alcohols on the Enantioseparation of Six Antihistamines
| Compound | Isopropanol (modifier) |
Ethanol (modifier) |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| tR1 | tR2 | α | RS | % | tR1 | tR2 | α | RS | % | |
| Doxylamine | 43.242 | 48.635 | 1.13 | 0.36 | 5 | 22.684 | 25.795 | 1.16 | 0.41 | 5 |
| 23.199 | – | – | 10 | 14.547 | – | – | 10 | |||
| Carbinoxamine | 27.077 | – | – | 10 | 14.768 | – | – | 10 | ||
| Cetirizine | 46.722 | 56.422 | 1.22 | 1.43 | 5 | 18.987 | 21.357 | 1.15 | 2.02 | 5 |
| 25.037 | 30.295 | 1.24 | 1.76 | 10 | 12.157 | 13.383 | 1.14 | 1.87 | 10 | |
| 14.513 | 17.308 | 1.25 | 1.88 | 20 | 8.666 | 9.348 | 1.12 | 1.59 | 20 | |
| 11.167 | 13.159 | 1.25 | 1.66 | 30 | 7.128 | 7.637 | 1.13 | 1.47 | 30 | |
| 10.578 | 12.254 | 1.22 | 1.53 | 40 | 6.819 | 7.213 | 1.11 | 1.30 | 40 | |
| Hydroxyzine | 38.088 | 40.725 | 1.08 | 0.51 | 5 | 22.191 | – | – | 5 | |
| 21.465 | 22.507 | 1.06 | 0.41 | 10 | 12.592 | – | – | 10 | ||
| 13.274 | – | – | 20 | 8.220 | – | – | 20 | |||
| Oxomemazine | >100 | – | – | 10 | 38.864 | – | – | 10 | ||
| Dioxopromethazine | >100 | – | – | 10 | 41.684 | 42.809 | 1.03 | 0.37 | 10 | |
| 52.189 | – | – | 20 | 19.736 | 20.144 | 1.03 | 0.32 | 20 | ||
| 31.660 | – | – | 30 | 13.057 | 13.237 | 1.02 | 0.26 | 30 | ||
| 22.849 | – | – | 40 | 10.183 | – | – | 40 | |||
tR1, tR2: retention times (min); α: separation factor; RS: resolution factor; “–” means that separation was not seen. Chromatographic conditions. The basic solvent of mobile phase was n-hexane, the temperature was at 25°C and the flow rate was 0.8 mL min−1.