[carnation]

There are many companies supplying the commercial buffer solution for pH measurement in fresh water. Why I could not find the commercial buffer solution for pH measurement in sea water. Is it true that people usually use buffer solution for fresh water in sea water measurement?

[Borek]

You mean calibrating buffers?

[carnation]

Yes

[Borek]

There are no separate buffers, no wonder you can't find them.

[carnation]

Normally, the buffer solution used for calibrating must have the similar background to the samples. For fresh water, it is OK if the buffer prepared in distilled water ( the ionic strenth is about 0.1). However, the sea water contains high concentration of salt (the ionic strenth is about 0.7). Therefore, IUPAC has recomendation to use the special buffer (tris buffer in synthetic sea water). Preparation the buffer for calibrating need high skill (very accurate). Therefore, I would like to buy the commercial one.

[Borek]

Perhaps I should put it differently - I don't recall seeing them.