Table IV.
Effect of Column Temperature on the Three Antihistamines
| Compound | tR1 | tR2 | α | RS | Temperature (°C) |
|---|---|---|---|---|---|
| Doxylamine | 9.019 | 9.837 | 1.14 | 2.44 | 15 |
| 8.301 | 8.881 | 1.11 | 2.32 | 20 | |
| 7.465 | 7.840 | 1.09 | 1.85 | 25 | |
| 7.156 | 7.456 | 1.07 | 1.65 | 30 | |
| 6.793 | 7.021 | 1.05 | 1.37 | 35 | |
| Cetirizine | 10.345 | 12.519 | 1.31 | 3.93 | 15 |
| 9.388 | 11.314 | 1.30 | 3.85 | 20 | |
| 8.625 | 10.208 | 1.29 | 3.74 | 25 | |
| 7.875 | 9.095 | 1.28 | 3.51 | 30 | |
| 7.353 | 8.368 | 1.27 | 3.20 | 35 | |
| Hydroxyzine | 21.379 | 23.435 | 1.11 | 2.10 | 15 |
| 18.969 | 20.561 | 1.10 | 1.93 | 20 | |
| 16.382 | 17.549 | 1.09 | 1.74 | 25 | |
| 14.925 | 15.840 | 1.08 | 1.56 | 30 | |
| 13.806 | 14.547 | 1.07 | 1.38 | 35 |
Chromatographic conditions. Doxylamine: mobile phase was n-hexane–ethanol (90/10, v/v, 0.1% DEA); cetirizine: mobile phase was n-hexane–isopropanol (60/40, v/v, 0.1% DEA); hydroxyzine: mobile phase was n-hexane–isopropanol (90/10, v/v/, 0.1% DEA). The flow rate was 0.8 mL min−1.