Abstract
The results of IAPSO Standard Seawater (SSW) comparisons are presented for batches P 132 to P 140. We try to match up our data with the previous result of comparison experiment to make the newest "offset table". According to the newest "offset table" proposed in this study, the standard deviation of the batch to batch differences among batches P 132 to P 140 is calculated to be 0.3 × 10-3 in salinity. This value is smaller than the value reported in the previous studies. The quality of SSW, from the point of view of batch to batch differences, has improved recently.
The SSW batch P 138 and P 140 were stored in bottles made from borosilicate glass and closed with chemically resistant plastic stoppers, while batches P 133 to P 137 and P 139 were stored in glass ampoules. We measured 30 bottles of P 138 and P 140 along with several ampoules of other batches in order to check the quality, those are, within-batch difference and batch-to-batch difference. The standard deviations (1σ) of 30 repeat measurements on P 138 and P 140 were both 0.3 × 10-3 in salinity. The difference between label-delived and measured salinity of P 138 referred to batch P 137 was -0.1 × 10-3 and that of P 140 reffered to batch P 139 was -0.5 × 10-3 in salinity. These values are comparable with other batches stored in a traditional glass ampoules. This result shows that SSW in a shot-bottle is, at least as for P 138 and P 140 at this moment, almost equivalent to SSW in a glass ampoule in quality.
