Sorry to break the news, but there's no such thing as pure
bicarbonate. The negatively-charged bicarbonate complex of atoms only
exists in stable form in combination with other atoms, such as sodium,
generally forming a chemical compound known as a salt.
The closest you can come is probably club soda, which is carbon
dioxide gas dissolved in water. Some of the CO2 reacts with the H2O
to form carbonic acid. The chemical formula for carbonic acid is
H2CO3, while bicarbonate is HCO3 (with a negative charge).
Fisher Scientific is a well-known source of chemical supplies. As you
can see from a product search for [ bicarbonate ] at their website:
there are quite a number of bicarbonate compounds, including:
However, there is no offering for Bicarbonate on it's own. It only
occurs in combination with other chemicals.
This Wikipedia article on bicarbonate will give you a bit of
background on the chemistry:
and this article on the related substance, Carbonic Acid, contains
even more detail:
Note, in particular, the section here on "Instability of carbonic
acid", which will give you an idea of the difficulty in bringing into
existence some chemicals on their own.
There is no common grocery-store source of bicarbonate that I am aware
of, other than sodium bicarbonate, so you may be stuck with this
compound as a source of bicarbonate ions, for the time being.
I trust this information fully answers your question.
However, please don't rate this answer until you have everything you
need. If you would like any additional information, just post a
Request for Clarification to let me know how I can assist you further,
and I'm at your service.
All the best,
search strategy -- Google search on [ bicarbonate ]