Eichrom’s Pb Resin is an extraction chromatographic material based on the same crown ether extractant used in the Sr Resin (Figure 1) but at a lower concentration and with a longer chain alcohol for a diluent to facilitate the stripping of Pb from the resin. Figure 2 shows the uptake of Pb together with several +1 cations and Figure 3 shows Pb together with representative alkali earth metals. Note the similarities to the uptake of these elements on Sr Resin. The retention of Pb is high (i.e., k’ > 100) across the range of nitric acid concentrations from 0.1M to 10M. Pb can be eluted from the column using 20 mL of water.
The effect of matrix constituents on lead uptake by the Pb Resin is similar to that for strontium on the Sr Resin. In Figure 4 it can be seen that calcium and sodium have little or no effect on Pb uptake even at concentrations up to 1M. Potassium does reduce Pb uptake as its concentration increases. Fortunately the retention of Pb on the Pb Resin is sufficiently high that methods can accommodate up to 1M potassium before the k’ of Pb drops below 100.
While the uptake of Pb on Pb Resin is maximized in nitric acid, it is possible to load Pb on the resin from HCl.
Figure 5 shows a comparison of the uptake curves for Pb from nitric and hydrochloric acid. Above 0.1M there is a divergence in the curves, with the nitric acid curve heading higher. There is still adequate retention from HCl at concentrations up to 1M. Above this HCl concentration, the retention of Pb drops off steeply. Vajda, et al. (VN195)published an HCl uptake curve for Pb on Sr Resin that corresponds to this behavior. Vajda reported a method for lead and polonium that allowed Pb to be stripped with 6M HCl. By analogy, this should be possible with Pb Resin as well.
In Table 1 are shown the elution behavior of various elements on the Pb Resin from 0.1M HNO3. With the exception of Pd, all elements tested eluted quantitatively in the first 10 free column volumes.
Pb Resin is manufactured in three particle sizes (20-50µ, 50-100µ, and 100-150µ) and is sold in bottles or ready to use in prepackaged columns (for gravity flow) and cartridges (for vacuum assisted flow.) Click here for part numbers and descriptions.
Source for all published data: Horwitz, E.P.; Gale, N.H.; et al, A Lead-Selective Extraction Chromatographic Resin and Its Application to the Isolation of Lead from Geological Samples, Analytica Chimica Acta, Vol. 292, pp. 263-273(1994)