Simultaneous determination of arsenic and uranium by the diffusive gradients in thin films technique using Lewatit FO 36: Optimization of elution protocol

The sorption ability of Lewatit FO 36-DGT resin gel, which has been developed for arsenic determination, towards uranium was tested by batch experiments within this study for the first time. Since the uptake efficiency of uranium was 99.0 +/- 0.4% and the maximum uptake capacity was not achieved even at the U spike of 1250 mu g in the solution, the Lewatit FO 36 resin seems to be a suitable binding phase for DGT resin gels for the determination of uranium. The resin gel also does not display any significant sorption selectivity in favour of one element over another. A novel protocol for simultaneous elution of arsenic and uranium from Lewatit FO 36 resin gel was therefore proposed in this study. The elution efficiencies of 90.3 +/- 3.9% and 85.2 +/- 3.1% for As and U, respectively, were obtained using 5 mL of 1 M NaOH at 70 degrees C for 24 h. The comparison with the original elution protocol using microwave-assisted elution by 0.25 M NaOH and 0.17 M NaCl at 130 degrees C for 16 min indicates, that the novel elution protocol provides good results in the performance of arsenic elution and, in addition, allows simultaneous elution of uranium. Moreover, the elimination of NaCl from the elution process allows a fast and simple analysis of both elements using ICP-MS, and therefore, the Lewatit FO 36-DGT technique can become more commonplace among laboratories without the need to modify the analytical method as proposed in the original study.

Automated summary

In this study, the Lewatit FO 36-DGT resin gel showed high uptake efficiency for uranium and a new elution protocol was proposed for simultaneous elution of arsenic and uranium. The elution efficiencies for As and U were found to be satisfactory, and the new protocol also allowed for fast and simple analysis of both elements using ICP-MS. This suggests that the Lewatit FO 36-DGT technique could become more widely used in laboratories without the need for modifications to existing analytical methods.