Application of a Stepwise Flow Ratiometry without Phase Separation to the Determination of the Chloroform/Water Distribution Coefficients of Volatile Diazines

概要

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The chloroform/water distribution coefficients (K_D) of sixteen diazine compounds were determined by a stepwise flow ratiometry. An aqueous solution of analyte was delivered and merged with chloroform. The flow rate ratio of both the phases was varied stepwise under a constant total (chloroform+aqueous) flow rate. The analyte was extracted to chloroform while both the phases, which were segmented by each other, were passing through an extraction coil. The segmented stream was then led to a UV/Vis detector directly without phase-separation. The absorbance of the chloroform and aqueous phases (A_o and A_a, respectively) was each measured at the maximum absorption wavelength of the analyte. The plots of A^<-1> against R_f, (AR_f)^<-1> against R^<-1>_f, and AR_f against A gave straight lines, where A was A_o, A_a or the sum of them (A_s). The K_D of the analyte was calculated from the slopes and intercepts of the plots. The log K_D values obtained for the analytes (-0.5-1.4) were agreed well with the values measured by a shake-flask method. The present method is simple, rapid (5min/determination) and applicable to the volatile compounds with reasonable precision (standard deviation of log K_D<0.07).
公益社団法人日本薬学会の論文
2005-04-01