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- Author or Editor: G. Mong x
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Abstract
Several organophosphorus compounds including tributyl phosphate (TBP), bis-2-(ethylhexyl) phosphate (D2EHP), and dibutyl butyl phosphonate (DBBP) were used as extractants at the Hanford site. The mass spectral fragmentation patterns of various organosphosphorus compounds have been interpreted and used to predict the identity of phosphate-related components and their degradation products in tank waste.
Abstract
Considerable attention has been focused on chelators such as ethylenediaminetetraacetic acid (EDTA) and N-(2-hydroxyethyl)ethylenediaminetriacetic acid (HEDTA), which form water-soluble complexes with most heavy metals. Most radionuclides are included in this class of constituents. As a result, chelator complexes have become very important environmentally because of their tendency to enhance the mobility of heavy metals through the soil and potentially contaminate groundwater. In addition, there is a correlation between chelator concentration and crust formation/gas release. The chelators are a class of compounds whose low volatility and high polarity preclude analysis by gas chromatography/mass spectrometry (GC/MS) without prior derivatization. Waste samples from a double-shell storage tank at Hanford were derivatized with BF3/methanol and analyzed using GC/MS. Results indicate the presence of EDTA, HEDTA, nitrilotriacetic (NTA), and citric acid. Nitrosoiminodiacetic acid was identified and determined to be an artifact of the derivatization procedure; it is assumed to arise from nitrosation of iminodiacetic acid in the waste sample.
Abstract
Ion-pair chromatography was tested for its applicability in determining monobutyl phosphate (MBP) and dibutyl phosphate (DBP), which are degradation products of tributyl phosphate, in Hanford tank wastes. In tests with simulant waste mixtures, tetrahexylammonium bromide, an ion-pairing agent, was used to complex with all three phosphate species. Recovery studies indicated that ion-pairing chromatography is quantitative for determining the analytes in spiked samples. Initial results demonstrated that DBP could be detected easily and was fairly well separated from other peaks, but MBP was frequently lost due to large negative peaks. Then a preconcentration column procedure was used to clean up the waste-sample matrix, and the negative peaks disappeared. Results indicated that 80% of MBP and 90% of DBP could be recovered. Most of the radioactivity was removed from actual waste tank samples so that additional sample preparation could be performed safely in a fume hood rather than a hot cell. Dibutyl phosphate was identified in an actual tank waste, but MBP was not found; this result was confimed by ion chromatography with conductivity detection.
Abstract
Tank wastes are usually very basic, pH>12, and extremely radioactive. An ion exchange method for removing most of the radioactive components has been developed. The sample can then be removed from the hot cell facility to be analyzed for chelator, chelator fragments, and low-molecular weight acids. The use of cation exchange resin in the sample preparation does not introduce or remove any organic carbon.
Abstract
A technique has been developed for the qualitative determination of low-molecular-weight organic acids in radioactive, mixed hazardous wastes using thermospray liquid chromatography/mass spectrometry. A tank waste was analyzed, and the results indicated the presence of citric, glycolic, acetic, and nitrosoiminodiacetic acid (NIDA). Further investigation revealed NIDA was formed under acidic conditions with the reaction of iminodiacetic acid and the high nitrate/nitrite concentration present in the waste.
