Table 5.

Room-temperature stability and triple freeze-thaw stability of four tanshinones in QC samples at three concentration levels (n = 6).

Analytes	Spiked Conc. (ng/mL)	Room-Temperature Stability		Freeze-Thaw Stability
		Measured Conc. (ng/mL)	RSD (%)	Measured Conc. (ng/mL)	RSD (%)
Tanshinone IIA	4.32	4.05 ± 0.24	5.98	4.11 ± 0.24	5.77
	21.6	19.58 ± 0.57	2.90	19.62 ± 0.37	1.83
	108	90.39 ± 4.07	4.51	92.15 ± 4.40	4.77
Cryptotanshinone	4.44	3.91 ± 0.30	7.56	3.86 ± 0.24	6.20
	22.2	20.47 ± 0.86	4.21	20.27 ± 1.17	5.75
	111	96.75 ± 4.09	4.22	96.55 ± 3.31	3.43
Dihydrotanshinone I	4.56	4.12 ± 0.18	4.32	4.1 ± 0.16	3.79
	22.8	20.4 ± 0.88	4.35	19.67 ± 1.48	1.89
	114	96.79 ± 2.51	2.59	94.75 ± 3.25	3.43
Tanshinone I	4.28	3.9 ± 0.24	6.13	3.91 ± 0.24	5.41
	21.4	20.05 ± 0.89	4.44	20.24 ± 0.89	3.69
	107	92.98 ± 3.73	4.01	91.54 ± 3.73	2.56