Potentiometric Stripping Analysis of Cadmium and Lead with Constant Inverse Current in the Analytical Step Using an Open Tubular Mercury-Coated Glassy Carbon Electrode

Table 3

Results of the analysis of the certified reference material of skimmed milk powder (ERM-BD151).

Element	Certified value (mg/kg)	Uncertainty^a (mg/kg)	Obtained value^b (mg/kg)	Bias (%)	texp	tcrit^c
Cd	0.106	0.013	0.103 ± 0.015	−2.83	0.89	2.78
Pb	0.207	0.014	0.203 ± 0.017	−1.93	1.05	2.78

^aAs indicated in the ERM-BD151 certificate. ^bMean value ± 2 SD of five independent analysis of ERM-BD151. ^c; f = 4.