Certified Reference Material (CRM).

500 mg/L of Ca, K, Mg, Na; 20 mg/L of Al, Ba; 10 mg/L Fe; 6 mg/L Sb; 5 mg/L of Co, V; 4 mg/L Ni; 2.5 mg/L Cu; 2 mg/L Zn; 1.5 mg/L Mn; 1 mg/L of Ag, As, Cr, Tl; 0.5 mg/L of Be, Cd; Se, 0.3 mg/L Pb in HNO₃ 5%