Table 6.

Stability data for of D3 and its major metabolites in human serum under different storage conditions using the developed UHPLC-ESI-MS/MS method.

	Nominal conc. (ng mL −1)	Accuracya (RE%)
Stability tests		D3	25(OH)D3	1,25(OH)2D3
Short-term stability	0.05	−3.2	−3.2	−3.6
	5	2.1	1.9	1.3
	50	−1.4	- 2.1	−1.0
Long term stability	0.05	- 4.1	−4.2	−4.9
	5	−3.2	−2.6	−3.4
	50	2.2	2.7	2.9
Autosampler stability	0.05	−2.8	−2.4	−2.1
	5	−2.2	−2.0	−1.8
	50	0.4	0.8	1.2
Freeze–thaw stability	0.05	−3.8	−4.3	−4.8
	5	2.9	2.5	2.7
	50	−1.7	−1.8	−2.1

^aAverage of five determinations.