Table 3A.

Estimation of Expanded Uncertainties for LC-MS/MS Measurements of Serum 25(OH)D₃

	Conc 1 (ng/g)	Conc 2 (ng/g)	Conc 3 (ng/g)
Mean	6.311	15.287	26.972
Type A
Standard deviation	0.037	0.052	0.062
Standard deviation of mean	0.012	0.017	0.021
Type B
1 % Uncertainty of systemic error	0.063	0.153	0.270
0.14 % Uncertainty of purity of reference  compound	0.009	0.021	0.038
0.1 % Uncertainty of weighing	0.006	0.015	0.027
Combined standard uncertainty (uc)	0.065	0.156	0.274
Coverage factor (k)	2	2	2
Expanded uncertainty (U)a	0.130	0.312	0.549
Relative expanded uncertainty, %	2.1	2.0	2.0

^a95 % confidence interval.