Hi there, I would like to extract calcareous soils with the Olsen method and, after dilution, inject the sample into a IC system in order to quantify phosphorous. I use isochratic carbonate/bicarbonate eluent and the carbonate peak due to the Olsen extractant always ends up behind or close to the nitrate peak. I tried to acidify the Olsen extracted solution but I did not manage to get rid of the soluble CO2. I would like to analyze both nitrate and phosphate together. Do you have any suggestion on how to remove the CO2 or, alternatively, on a different eluent (may be acidic) that, on the other hand, remain very sensitive?
Thanks.
You can try use different composition of eluent or Carbonate Removal Device (e.g. http://www.dionex.com/en-us/products/accessories/reagents-accessories/crd/lp-73608.html) for reduction signal of carbonates.
Dilute your extract to match the eluant strength. Since you'll find a lot of nitrate and phosphate in soil you'll have plenty of sensitivity; besides, diluting the sample will actually help enhance your signal (lower ionic strength).
Thanks guys. Vaclav your suggestion is certainly interesting although I am looking for something chipper . Mark I agree I should be able to extract a lot of phosphate and nitrate from soil but the extracting solution would be NaHCO3 0.5M. The eluent for the IC is around 1mM sodium carbonate e 1mM sodium bicarbonate. I can not diluite 500 times, in this case I would definitely go under the detection limit. Thanks for suggestions!
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