A Simple Ultraperformance Liquid Chromatography-Tandem Mass Spectrometry Method for Measurement of Cortisol Level in Human Saliva
Table 3
Stability of cortisol in human saliva.
Stability
Storage condition
Spiked concentration (ng/ml)
Measured concentration (ng/ml)
SD
Stability ()
Processed samples
24 hr. (RT)
1.5
1.34
0.06
89
90
78.91
3.39
88
48 hr. (-20°C)
1.5
1.29
0.02
86
90
77.48
1.61
86
Un-processed samples
24 hr. (RT)
1.5
1.59
0.04
100
90
82.68
1.33
92
20 wks (−20°C)
1.5
1.36
0.17
91
90
87.90
4.73
98
Freeze and Thaw samples
FT: Cycle-1
1.5
1.42
0.07
95
(−20°C)
90
85.33
2.28
95
FT: Cycle-2
1.5
1.54
0.12
100
(−20°C)
90
83.25
1.75
93
FT: Cycle-3
1.5
1.43
0.11
95
(−20°C)
90
86.39
2.76
96
RT: room temperature, hr.: hours, wks: weeks, FT: Freeze-Thaw. Stability (%): mean measured concentration (n=5) at the indicated time divided by mean measured concentration (n=5) at baseline x 100.
