Table II.
Stability studies for thalidomide (4 samples each concentration).
| Stability experiment | Storage condition | Nominal concentration (ng/ml) | Calculated concentration, mean ± SD (ng/ml) | RE (%) | RSD (%) |
|---|---|---|---|---|---|
| Freeze/thaw stability | After third freeze/thaw cycle at −80°C | 5 | 4.593±0.10 | 0.93 | 1.98 |
| 50 | 52.80±2.91 | 5.59 | 5.51 | ||
| 1200 | 1189±10.02 | 1.00 | 0.84 | ||
| Long-term stability | For 6 months at −80°C | 5 | 5.166±0.08 | 3.33 | 1.58 |
| 50 | 50.39±0.82 | 0.79 | 1.63 | ||
| 1200 | 1201±21.01 | 0.05 | 1.75 | ||
| Room temperature stability | Room temperature for 4 h | 5 | 5.297±0.19 | 5.94 | 3.56 |
| 50 | 56.75±0.38 | 13.50 | 0.67 | ||
| 1200 | 1269±75.08 | 5.78 | 5.92 |
RE, relative error (accuracy); RSD, relative standard deviation (precision).