[marinka]

Hi everybody!
I need to identify small concentration (about 0.1 mg/ml) of hydrogencarbonates in solution. I tried to boil the sample and bubble the CO2 through a solution of barium hydroxide and I didn't get any precipitate (probably because of the small concentration of hydrogencarbonates). Does anyone know a method sensitive enough to identify these small concentrations?
Thanks,
Bye

[Arkcon]

I would suggest ion chromatography to accurately quantitate low concentrations of anions, including carbonates and bicarbonates.

[Borek]

Around 10^-3 M, relatively low for classic methods.

That being said, why don't you add barium hydroxide (plus some NaOH) directly to the sample solution? Do you have anything present in the solution (sulfates? carbonates?) that will interfere with this approach?

[marinka]

Thank you for your answers. My sample is seawater, so if I add barium hydroxide directly I would probably get barium chloride precipitate. For ion chromatography I need to modify my instrument in way which is too expensive for this purpose. Is this identification possible with HPLC or UV?

[Borek]

My sample is seawater, so if I add barium hydroxide directly I would probably get barium chloride precipitate.

Sulfate.

Is this identification possible with HPLC or UV?

Not that I know of.