Direct determination of uranium and co-extracted elements in the organic phases (D2EHPA/TOPO, TBP, TDA) in kerosene by TXRF technique

The total reflection X-ray fluorescence (TXRF) spectrometry was used for direct determination of uranium concentration in the organic phase di-(2-ethyl hexyl) phosphoric acid and trioctyl phosphine oxide (D2EHPA-TOPO)/kerosene, which resulted from first and second cycles of uranium extraction from wet-process phosphoric acid.The TXRF measurements were performed using gallium as an internal standard. A linear relationship between relative intensity of uranium vs. gallium (IU/SGa) against uranium concentration has been obtained.Four calibration curves, 0–5, 5–100, 100–1000 and 1000–7000 μg mL−1, according to uranium concentration in the studied samples, were constructed. The detection limit was found to be 0.15 μg mL−1.The effect of D2EHPA and TOPO concentration in kerosene on uranium determination was considered. The TXRF spectrometry was also applied for the multi-elemental analysis of the co-extracted impurities with uranium, such as (Fe, Ni, Cu and Zn) in the organic phase, and four calibration curves, 0–500 μg mL−1 Fe, 0–20 μg mL−1 Ni, 0–10 μg mL−1 Cu and 0–20 μg mL−1 Zn, according to Fe, Ni, Cu and Zn concentration in the studied samples were performed, respectively, using gallium as an internal standard.The obtained results using direct TXRF analysis method were in a very good agreement with those obtained by fluorometry method, which is suitable for aqueous solutions after stripping of uranium from the organic phase by 1 M Na2CO3.