Table 3.

Stability of Bu in human plasma under various storage conditions.

Nominal concentration (ng/mL)	50	500	1250	1750
Autosampler at 22 °C (24 h)
Mean conc found (n = 8)	54.85	494.68	1274.07	1702.43
RSD, %	8.34	4.38	3.61	2.35
Bias, %	9.7	−1.06	1.93	−2.72
Freeze-thaw
Mean conc. found (n = 5)	46.85	484.95	1221.48	1716.5
RSD, %	2.79	2.84	2.37	2.54
Bias, %	−6.3	−3.01	−2.28	−1.91
Long-term stability at −80 °C (1 month)
Mean conc. found (n = 6)	51.94	486.63	1231.73	1690.13
RSD, %	10.59	7.58	2.61	3.18
Bias, %	3.9	−2.8	−1.5	−3.4
Bench-top stability (25 °C for 24 h)
Mean conc. found (n = 6)	54.85	494.68	1274.07	1702.43
RSD, %	8.34	4.38	3.61	2.35
Bias, %	9.7	−1.1	1.9	−2.7