A small high-pressure ion-exchange system has been used together with liquid-liquid extraction to achieve decontamination sufficient to permit the determination by beta counting of Z49Bk isolated from highly radioactive solutions. A high-pressure pump forces solutions through a column of Dowex 50 resin (20to 40-tdiam particles) at pressures from 1800 to 2500 psi. The eluent is a dilute aqueous solution of a-hydroxyisobutyric acid of pH 4.2. The eluted 249Bk is purified by extraction into 2mthenoyltrifluoroacetone-xylene. I n this way the *49Bk is separated sharply from many elements including the actinides, fission products, and corrosion products. Separations can be effected at eluent flow rates as fast as 18 m l ern+ min-l, thereby minimizing loading time, elution time, and radiation damage to the resin. High-pressure operation makes possible the use of a long column (-2 ft) having a small free column volume (-1 ml).

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