Samples Containing Strontium or Barium

Hydrolytic Stability and Preferred Matrices

• Ba and Sr begin to precipitate (as the carbonate due to dissolved CO₂) from solution at a pH of between 6.2 (high conc.) to 10 (low conc.).
• Following are solubility data for Sr and Ba as compared to Ca (g/100 mL H₂O):

• The following table shows the improvements in the hydrolytic stability of Ba⁺² and Sr⁺² with different complexing agents. The pH where precipitation of BaCO₃ and SrCO₃ begins is shown for 0.1 M solutions of each complexing agent:

• Ba and Sr can be mixed with any of the elements at high concentrations (200 to 2000 µg/mL) with the exception of the fluoride containing elements (Ti, Zr, Hf, Nb, Ta, W, Si, Ge, Sn, Sb, Mo) and hexavalent chrome and sulfate in the case of Ba. Moderate to low levels (≤ 100 µg/mL) can be mixed with all of the elements except moderate to high levels of fluoride (F-) and sulfate (Ba only).
• Ba and Sr have relatively simple emission spectra. Popular emission lines are the (Sr) 460.733 nm line with a DL of ~0.002 µg/mL (axial view) and the (Ba) 455.404 nm line with a DL of 0.00008 µg/mL (axial view). These lines are popular because of their relative freedom from spectral interference combined with high sensitivity.

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