Three lots of CRMs are available as below.
7601-a Seawater for Nutrients - Extremely Low Concentration
7602-a Seawater for Nutrients - Middle Concentration
7603-a Seawater for Nutrients - High Concentration
NMIJ CRM web site is below;
https://www.nmij.jp/english/service/C/
Samples of certificate of three lots can be obtained from below.;
https://www.nmij.jp/english/service/C/crm/60/7601a_en.pdf
https://www.nmij.jp/english/service/C/crm/60/7602a_en.pdf
https://www.nmij.jp/english/service/C/crm/60/7603a_en.pdf