Measurement of Magnesium, Zinc, and Copper in Human Serum by Using Isotope Dilution Inductively Coupled Plasma Mass Spectrometry (ID ICP-MS)

Table 4

Sources of uncertainty in the determination.

Sources of uncertainty	Mg		Zn		Cu
	GBW09152		GBW09152		GBW09152
	Value (xi)	uc (xi)	Value (xi)	uc (xi)	Value (xi)	uc (xi)
Type A uncertainties
RY	0.014	0.000	0.034	0.000	0.004	0.000
Rz	6.667	0.021	6.208	0.014	2.107	0.003
RBc	0.920	0.002	1.041	0.003	1.080	0.004
RB	0.885	0.003	1.004	0.003	1.049	0.002
CB (mg·kg^−1)	0.5	0.3	0.09	0.05	0.010	0.005
Type B uncertainties
Cz (mg·kg^−1)	19.398	0.003	1.290	0.002	1.008	0.002
mzc (mg)	3.0 × 10^2	0.040	2.6 × 10^2	0.040	5.4 × 10^2	0.040
mYc (mg)	5.5 × 10^2	0.040	2.0 × 10^2	0.040	4.0 × 10^2	0.040
mY (mg)	3.4 × 10^2	0.040	200 × 10^2	0.040	4.0 × 10^2	0.040
mx (mg)	2.0 × 10^2	0.040	300 × 10^2	0.040	4.8 × 10^2	0.040
Combined types A and B	—	0.25	—	0.045	—	0.011
Degrees of freedom (Veff)		8		8		8
Coverage factor (k)	—	2	—	2	—	2
Measured value (mg·kg^−1)	20.57	—	1.147	—	1.072	—
Expanded uncertainty (U(), k = 2) (mg·kg^−1)	—	0.2	—	0.04	—	0.08