Development of system for measurement of distribution coefficients based on flow ratiometry

流量比法是一种专门的连续流动分析，其中两种独立输送的溶液以不同的流量比合并。在两种溶液汇合点下游位置监测分析信号。本研究建立了一种快速、高通量测定药物分配系数K_D的流量比测定系统。主要研究结果如下：1.将体积比法与传统的摇瓶法相结合，提出了体积比法作为流量比法的基础。该方法成功地应用于苯酚及其相关化合物的K_D测定。2.采用分步流动比率法，通过改变氯仿水相的流量比，测定了各种化合物的K_D。在相分离后测量任一相中分析物的吸光度。此外，我们还开发了一种无需相分离的在线紫外检测方法，将检测速度提高到5 min/次。3.建立了基于反馈的流动比率法测定酸解离常数。通过将分析信号反馈到泵速，将滴定剂/被滴定物流量比的扫描范围缩小到半当量点附近。可获得良好的通量速率（26 s/测定）和良好的精密度（RSD= 3 s）。

Flow ratiometry is a specialized continuous flow analysis, where two independently delivered solutions are merged at various flow ratios. Analytical signal is monitored at the position downstream of the confluence point of the two solutions. The information of interest is determined by analyzing the relationship between the flow ratio and the analytical signal.In this study, we developed a flow ratiometry system for the rapid and high-throughput determination of the distribution coefficients K_D of drugs. The results obtained are as follows :1.We proposed "volume ratiometry", as a basis of flow ratiometry, by combining it with conventional shake-flask method. The method was successfully applied to the determination of K_D of phenol and its relation compounds.2.The K_D of various compounds was determined based on stepwise flow ratiometry, where the flow ratio of chloroformlaqueous phases were changed stepwise. The absorbance of analyte in either of the phases was measured after the phase separation. Further, we developed an on-line UV detection method without phase separation, which improved the throughput rate up to 5 min/determination.3.Feedback-based flow ratiometry was developed for the determination of acid dissociation constants. The scan range of titrant/titrand flow ratio was narrowed down to just the vicinity of the half equivalence point by the feedback of analytical signal to pump speed. Good throughput rate (26s/determination) was attainable with good precision (RSD=3s).