Certified valuesAl. 250 ng/mL Cu.100 ng/mL Pb . 25.0 ng/mL As. 50.0 ng/mL Fe .100 ng/mL Rb . 50.0 ng/mLB . 250 ng/mL K .1000 ng/mL S . 10000 ng/mL Ba . 250 ng/mL Mg .2000 ng/mL Se . 10.0 ng/mL Ca . 10000 ng/mL Mn .50.0 ng/mL Si. 5000 ng/mL Cd . 2.50 ng/mL