Chinese Primary Standard Seawater: Stability checks and comparisons with IAPSO Standard Seawater

- Brief preparation procedures of Chinese Primary Standard Seawater (CP SSW).
- Stability check method of CP SSW, with a demonstration check.
- Comparison method of CP SSW and IAPSO Standard Seawater (IAPSO SSW).
- Comparisons indicating no significant difference between CP SSW and IAPSO SSW.
- Measures taken to assure the reliability of SP measurement results.

The authors give a brief introduction to the Chinese Primary Standard Seawater, with a description of its preparation procedures. IAPSO Standard Seawater (IAPSO SSW), was taken as a stable reference in the stability check of Chinese Primary Standard Seawater (CP SSW), and linear regression model as well as hypothesis testing were introduced into the analysis of check results; a demonstration check of CP SSW (batch number P8) achieved a positive conclusion. In comparisons of several batches of these two kinds of standard seawater on Practical Salinity, identical seawater samples from a homogeneous source were measured repeatedly. To evaluate the comparison results, performance criteria referred to as En numbers were adopted, the maximum of which was 0.42, indicating that no significant differences lay between these two kinds of SSWs when used to determine Practical Salinity. Measures taken to assure the reliability of measurement results are presented.