Stability results of SP under different conditions.

Matrix	Test conditions	Theoretical concentration (ng mL−1)	Calculated concentration (ng mL−1) (Mean ± SD, n = 5)	Precision (RSD%)	Accuracy (%)
Plasma	Short-term stability (0 °C for 1 h)	0.25	0.241 ± 0.011	4.6	96.4
		150	144 ± 3.17	2.2	96.0
	Post-preparation stability (25 °C for 1 h)	0.25	0.227 ± 0.018	7.9	90.8
		150	158 ± 6.12	3.9	105.3
	Auto-sampler stability (4 °C for 24 h)	0.25	0.275 ± 0.009	3.3	110.0
		150	160 ± 7.17	4.5	106.7
	Freeze–thaw stability (three cycles)	0.25	0.266 ± 0.005	1.9	106.4
		150	142 ± 4.21	3.0	94.7
	Long-term stability (−70 °C for 60 days)	0.25	0.240 ± 0.005	2.1	96.1
		150	141 ± 3.85	2.7	94.0
Blood	Blood stability (0 °C for 1 h)	0.5	0.572 ± 0.078	13.6	114.4
		300	312 ± 10.0	3.2	104.1