Table 6.

Measured results for Pb, Cd, Hg, and Mn in NIST SRM 955c Toxic Metals in Caprine Blood over n=15 measurements.

NIST 955c SRM	Analyte	Target Value ( ±Ud)	Observed Mean Conc. ( ± 1 SD)	% Bias
Level 1	Pb (μg dL−1)	0.424 ± 0.011a	0.441 ± 0.024	4.0%
Level 2		13.95 ± 0.08a	13.7 ± 0.3	−1.8%
Level 3		27.76 ± 0.16a	27.4 ± 0.5	−1.3%
Level 4		45.53 ± 0.27a	44.4 ± 1.3	−1.9%
Level 2	Cd (μg L−1)	2.14 ± 0.24b	2.11 ± 0.08	−1.4%
Level 3		5.201 ± 0.038a	5.14 ± 0.19	−1.2%
Level 4		9.85 ± 0.17b	9.98 ± 0.39	1.3%
Level 2	Hg (μg L−1)	4.95 ± 0.76b	5.19 ± 0.20	4.8%
Level 3		17.8 ± 1.6a	18.4 ± 0.7	3.3%
Level 4		33.9 ± 2.1b	33.5 ± 1.7	−1.3%
Level 1	Mn (μg L−1)	16.3 ± 0.8c	16.8 ± 0.6	2.8%

^aCertified value.

^bReference value.

^cConsensus value.

^dExpanded uncertainty at approximately 95% confidence level.