Table 2. Stability of Psoralen in Rat Plasma (n = 5).

		stability (%, RSD)
concentration (μg/mL)	concentration measured (μg/mL)	room temperature (24 h)	long-term (30 days at –20 °C)	three freeze–thaw cycles at –20 °C
0.2	0.21 ± 0.04	0.08	3.62	2.83
2.0	1.97 ± 0.02	1.63	3.25	1.17
8.0	8.01 ± 0.17	0.17	1.84	2.17