Certified valuesAl. 50 ng/mL Cu.20 ng/mL Pb . 5.0 ng/mL As. 10.0 ng/mL Fe .20 ng/mL Rb . 10.0 ng/mLB . 50 ng/mL K .200 ng/mL S . 2000 ng/mL Ba . 50 ng/mL Mg .400 ng/mL Se . 2.00 ng/mL Ca . 2000 ng/mL Mn .10.0 ng/mL Si. 1000 ng/mL Cd . 0.50 ng/mL Mo .10.0