... 90 A was obtained from the Chemical Works, Qing Dao, China. ... Page 4. 1864 ANALYTICAL CHEMISTRY, VOL. 63, NO. ... C4-NH IO 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 volume fraction of water in methanol Figure 1. log k'as a function the eluent composition for dibenzo- 18-crown-6 ethers. ...