Table 2.

Certified versus measured concentrations (mg/L) of selected metals in standard reference material (SRM 1643d).

Metal	Certified	Measured
Ca	31.04	30.26
Cd	0.00647	0.006
Cr	0.01853	0.019
Co	0.025	0.022
Cu	0.0205	0.019
Fe	0.0912	0.092
K	2.356	2.385
Li	0.0165	0.015
Mg	7.989	7.816
Mn	0.03766	0.038
Na	22.07	21.77
Ni	0.0581	0.061
Pb	0.01815	0.019
Sr	0.2948	0.286
Zn	0.07248	0.071