DETERMINATION OF MONOBUTYL PHOSPHATE AND DIBUTYL PHOSPHATE IN MIXED HAZARDOUS WASTES BY ION-PAIR CHROMATOGRAPHY

Ion-pair chromatography was tested for its applicability in determinin g monobutyl phosphate (MBP) and dibutyl phosphate (DBP), which are deg radation products of tributyl phosphate, in Hanford tank wastes. In te sts with simulant waste mixtures. tetrahexylammonium bromide, an ion-p airing agent, was used to complex with all three phosphate species. Re covery studies indicated that ion-pairing chromatography is quantitati ve for determining the analytes in spiked samples. Initial results dem onstrated that DBP could be detected easily and was fairly well separa ted from other peaks, but MBP was frequently lost due to large negativ e peaks. When a preconcentration column proce dure was used to clean u p 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 a dditional 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 confirmed by ion ch romatography with conductivity detection.