Abstract: LITHIUM ISOTOPE EFFECT IN THE EXTRACTION SYSTEMS OF CROWN ETHERS ──EFFECT OF MIXED SALTS OF LITHIUMFang Shengqiang；Fu Li＇an（Department of Modern Physics,Lanzhou University,730000）ABSTRACT The mixed effect of two sorts of lithium salt in crown ether extraction systems has been exam-ined. A solution of 4-tert-butylbenzo-15－crown- 5 or 4-methylbenzo-15-crown- 5 in C_6H_5I was usedas extractant， and contacted with the aqueous solution of lithium salts which are LiSCN, LiClO_4，LiCN＋LiNO_3，LiClO_4＋LiNO_3 or LiClO_4＋Li-EDTA，respectively.Some parameters includinglithium concentration in organic phase C_0，destribution ratio D, isotope separation factor of lithium α，and isotope separation ability of crown ether to lithium ε_p，were determined. Comparing the parame-ters between systems of unitary salt and mixed salts the existence and magnitude of mixed salt effecthave been confirmed. It has been established that the values of αandε_p obtained in systems of mixedsalts is greater than that of unitary salt，and that the values of C_0 and D are slightly decreased，as ap-propriate lithium salts were selected to be used in the extraction systems of crown ethers.Key words crown ethers lithium isotopes isotopic effect isotope separation solvent extrac-tion