High-performance ion chromatographic separation of uranium and thorium in natural waters and geological materials

Separation Behavior of U(VI) and Th(IV) on a Mixed Ion Exchange Column Using 2,6-Pyridine Dicarboxylic Acid as a Complexing Agent and Determination of Trace Level Thorium in Uranium Matrix Employing High Performance Ion Chromatography

“…Interestingly, unlike the modified RP column, the mixed ion exchange column exhibited strong retention for Th (IV) whereas U(VI) got eluted immediately after the solvent front. Hence, the elution order observed in the present case is U(VI) followed by Th (IV), which is similar to that of the elution order obtained with strong cation exchange stationary phase [23,26,27]. This indicates that in the case of mixed ion exchanger, the chelation exchange mechanism responsible for retaining U (VI) and Th (IV) on the RP substrate is insignificant, probably the mixed ion exchanger column was not sufficiently modified with PDCA to get the elution order similar to that of the RP column.…”

“…Separation of U(VI) as UO 2 2+ on a low capacity strong cation exchanger has been reported [25]. Even though few studies reported the separation of U and Th from water and geological samples using a pure cation exchange column with gradient elution of a mobile phase consisted of HCl and Na 2 SO 4 [26,27], use of hydrochloric acid as eluent was not recommended for routine analysis due to its corrosiveness, which demanded utmost care on the instrument maintenance. Earlier in our laboratory, we have separated uranium and thorium using a short length cation exchange column using a mobile phase consisting of 0.08 mM PDCA in 0.24 M KNO 3 and 0.22 M HNO 3 (pH ~ 0.6) [23].…”

Separation and Determination of Thorium in Uranium Mineralizations Using a Mixed Ion Exchange Column by Ion Chromatography

“…Techniques such as radiochemistry (Clesceri et al, 1989), atomic absorption spectroscopy (Clesceri et al, 1989), neutron activation analysis (Honda et al, 1990), inductively coupled plasma mass spectrometry (ICP-MS) (Igarashi et al, 1990;Deb et al, 2008), isotope dilution mass spectrometry (Adriaens et al, 1992) and X-ray fluorescence (XRF) (Robinson et al, 1986) were earlier reported for the determination of Th in uranium matrix. However, these techniques are often not suited to routine analysis, due to interferences from other metals present in the matrix, cost of operation or poor detection limits (Harrold et al, 1992;Cassidy, 1998). Ion chromatography (IC) and high performance liquid chromatography (HPLC) are promising techniques for the separation of polyvalent metal cations by adding suitable complexing agents in the mobile phase Jackson et al, 1996;Vaibhavi Raut et al, 2013).…”

“…With both HCl and HN0 3 eluents, a relatively low acid concentration will elute UO 2 2+ as an anionic complex, but a much higher concentration of acid (>3 M) is required to elute thorium. Although an acid gradient can be used for the separation, this approach will cause difficulties in detec-tion (Harrold et al, 1992;Dionex Application Note, 1998;Al-Shawi and Dahl, 1995).…”

Determination of uranium in environmental matrices by chelation ion chromatography using a high performance substrate dynamically modified with 2,6-pyridinedicarboxylic acid

“…Using cation exchange, U(VI) was determined in process liquors using an ammonium sulphate/sulphuric acid eluent [2], U(IV) and U(VI) were separated and determined in uranium compound mixtures using a magnesium sulphate/sulphuric acid eluent [3], and uranium and thorium were determined in nitrophosphate fertilizer solution using either hydrochloric acid or nitric acid together with ammonium sulphate in the eluent [4]. Another system utilised a preconcentration step on an iminodiacetate (IDA) functionalised chelating resin, followed by cation exchange with a hydrochloric acid/sodium sulphate gradient, for the determination of uranium and thorium in natural waters and geological materials [5]. Investigations with reversed phase liquid chromatography (RP-HPLC), using complexing agents in the eluent as a method to separate and determine uranium and other actinides, has also received particular interest.…”