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量分析方法，其中两种独立提供的解决方案以不同的流量比合并。在两种溶液汇合点下游的位置监测分析信号。通过分析流量比和分析信号之间的关系来确定感兴趣的信息。在本研究中，我们开发了一种用于快速、高通量地测定药物分配系数K_D的流量比法系统。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。将该方法成功地应用于苯酚及其相关化合物的K_D测定。2.通过逐步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，测量分析物在任一相中的吸光度。此外，我们还开发了一种不需要相分离的在线紫外检测方法，将吞吐量提高到5min/次。3.建立了基于反馈的流动比值法测定酸解离常数。通过分析信号对泵速的反馈，将滴定剂/滴定流量比的扫描范围缩小到半等效点附近。方法精密度好(RSD=3s)，重现性好(26s/次)。

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).