Simultaneous Quantification of Aspirin, Its Metabolite Salicylic Acid, and Salvianolic Acid B in Human Plasma Using UPLC-MS/MS

Table 5

Stability of Sal B, ASA, and SA.

Nominal conc. (ng/mL)	Storage in autosampler at 4°C for 24 h (n = 3)		Storage in freezer at −80°C for 60 days (n = 6)		Storage at 25°C for 4 h after acidification (n = 6)		Storage at 25°C for 4 h without acidification (n = 6)
	Observed conc. (ng/mL)	Accuracy (RE%)	Observed conc. (ng/mL)	Accuracy (RE%)	Observed conc. (ng/mL)	Accuracy (RE%)	Observed conc. (ng/mL)	Accuracy (RE%)
Sal B
15	16.7 ± 0.6	11	15.9 ± 0.8	6	15.2 ± 1.0	1.3	10.1 ± 1.1	−33
3000	3047 ± 85	1.6	2920 ± 63	−2.7	2767 ± 85	−7.8	2580 ± 61	−14
4500	4490 ± 358	−0.2	4438 ± 179	−1.4	4370 ± 290	−2.9	3988 ± 164	−11
ASA
15	17.0 ± 0.3	13	14.1 ± 0.5	−6	15.9 ± 0.7	6	8.47 ± 0.6	−44
3000	3357 ± 90	12	3117 ± 27	3.9	3260 ± 96	8.7	1762 ± 87	−41
4500	4747 ± 274	5.5	4242 ± 110	−5.7	4470 ± 206	−0.7	2767 ± 179	−39
SA
15	15.9 ± 1.3	6	14.8 ± 1.2	−1.3	16.1 ± 0.9	7.3	18.3 ± 0.5	22
3000	2797 ± 59	−6.8	3138 ± 86	4.6	2892 ± 37	−3.6	3767 ± 78	26
4500	4233 ± 188	−5.9	4635 ± 156	3	4293 ± 91	−4.6	5738 ± 216	28

RE% = (mean of observed conc. − nominal conc.)/nominal conc. × 100%.