Table 3.

Assessment of the bias of 25(OH)D₂ detected by LC-MS/MS using NIST certified SRM-972a

SRM-972a 25(OH)D2	Certified values by NIST		LC-MS/MS
	Target values (ng/mL)	Uncertainty	Detected values (ng/mL)	SD (n = 3)	Bias(%)
Level 1	0.50	0.06	0.48	0.07	−4.17
Level 2	0.81	0.06	0.84	0.05	4.45
Level 3	12.90	0.30	12.72	0.26	−1.40
Level 4	0.50	0.10	0.51	0.04	2.26

SRM standard reference material, NIST National Institute of Standards & Technology