Doyle T D, Barkan S
J Assoc Off Anal Chem. 1976 Sep;59(5):1170-4.
The partition of tolbutamide (1-butyl-3-(p-tolylsulfonyl) urea) as ion-pairs with homologous tetraalkyl ammonium cations was studied. The determination of experimental extraction constants permitted quantitative calculation of distribution ratios, in agreement with theoretical relationships, over a continuous range of about one billion. The nature and the concentration of the counter-ion and solvent composition were the variables studied. Based on the theoretical results, a rapid partition chromatographic procedure was devised. A solution of tolbutamide sample in 10% aqueous tetraethyl ammonium hydroxide is incorporated in the system as the immobile phase in the partition column. A 1+1 mixture of chloroform and isooctane removes extraneous materials; then chloroform elutes the tolbutamide-tetraethyl ammonium ion-pair, which is converted to the free acid by passing the eluate through a phosphoric acid segment, and tolbutamide is determined spectrophotometrically without further treatment. Standard recoveries averaged 100.5+/-0.70%; commercial tablets assayed 100.5+/-0.85%.
研究了甲苯磺丁脲（1-丁基-3-（对甲苯磺酰基）脲）与同系四烷基铵阳离子形成离子对的分配情况。通过测定实验萃取常数，可根据理论关系在约10亿的连续范围内对分配比进行定量计算。研究的变量包括抗衡离子的性质和浓度以及溶剂组成。基于理论结果，设计了一种快速分配色谱法。将甲苯磺丁脲样品在10%氢氧化四乙铵水溶液中的溶液作为固定相引入分配柱系统。氯仿和异辛烷的1+1混合物用于去除杂质；然后氯仿洗脱甲苯磺丁脲-四乙铵离子对，洗脱液通过磷酸段后转化为游离酸，无需进一步处理即可用分光光度法测定甲苯磺丁脲。标准回收率平均为100.5±0.70%；市售片剂的测定结果为100.5±0.85%。
