Storage condition

Nominal concentration (ng/mL)

Measured concentration (ng/mL)

Recovery (%)

Short term stability (6 h in plasma)

0.30

109210^*

86.96

5.50

-

-

8.80

3783601^*

98.33

Autosampler stability after 65 h

0.30

0.28

103.70

5.50

-

-

8.80

9.41

97.82

Freeze-thaw cycles (N = 5)

0.30

0.28

93.33

5.50

6.09

110.73

8.80

9.66

109.77

Long term stability (198 day, −80˚C)

0.30

0.27

91.11

5.50

5.62

102.12

8.80

9.04

102.72