毛细管区带电泳法测定甲氧苄胺嘧啶和磺胺甲基异噁唑的离解常数及其在复方新诺明中的含量

Determination of Dissociation Constants of Trimethoprim and Sulfamethoxazole and Their Concentrations in Co-trimoxazole Tablets by Capillary Zone Electrophoresis

报道了利用 ３０ ｍｍｌ／Ｌ ＨＡｃ－ＮａＡｃ为缓冲液测定复方新诺明中甲氧苄胺嘧啶（ＴＭＰ）和磺胺甲基异噁唑（ＳＭＺ）的离解常数及含量的毛细管区带电泳（ＣＺＥ）方法。该方法具有简便、快速、准确等特点。测得ＴＭＰ和ＳＭＺ的ｐＫａ分别为６．６０和５．９０。其平均回收率分别为１０１．５％和９９．６％，最低检出限为０．４８ ｍｇ／Ｌ和０．０２８ ｍｇ／Ｌ，ＲＳＤ为１．２６％和１．１２％。

A rapid and reliable capillary zone electrophoresis method has been established for the determination of trimethoprim and sufamethoxazole in co-trimoxazole tablets as well as their dissociation constants. With 30 mmol/L acetate as buffer electrolyte (pH = 5. 55), the two components in co- trimoxazole tablets were separated, and ethanol used as solvent in analysis procedure did not interfere with their determination. The relative standard deviation for trimethoprim and sufamethoxazole was 1 .3% and 1.1%, respectively. The detection limit was 0.48 mg/L for trimethoprim and 0. 028 mg/L for sufamethoxazole. The recovery of trimethoprim was 101. 5% and that of sufamethoxazole was 99. 6%. The contents of trimethoprim and sufamethoxazole obtained by the method were in good agreement with the nominal values. It was that the capillary electrophoresis method could be employed conveniently to determine the dissociation constants of trimethoprim and sulfamethoxazole. The dissociation constant of trimethoprim and sulfamethoxazole obtained from capillary electrophoresis method was 6. 60 and 5. 90, respectively The determined dissociation constants were closed to the values append in some common physical and chemical handbooks.