15 components: Al 5mg/l As 5mg/l Ba 5mg/l Cd 5mg/l Co 5mg/l Cr 5mg/l Cu 5mg/l Mn 5mg/l Mo 5mg/l Ni 5mg/l Pb 5mg/l Se 5mg/l Sr 5mg/l Zn 5mg/l K 50mg/l in HNO3 1% CRM, ISO 17034 and ISO 17025,, Conservation 12 months. (6 mon 1 * 500 mL