혼합용매중에서의 산-고기 지시약에 관한 연구(I) : 수-유기용매 혼합용매중 Ampicillin, Amoxicillin 및 Cephalexin의 정량

Studies on Acid-Base Indicators in the Mixtures of Some Solvents(I) : Determination of Ampicillin, Amoxicillin and Cephalexin in Aqueous Organic Solvents

The pH titration curves of ampicillin, amoxicillin and cephalexin in aqueous acetone, ethanol and N,N'-dimethylformamide by use of 0.02 N-KOH solution showed that 80% acetone was the most effective solvent for alkali titration of them. The pH jumps of samples in 80% acetone were sharp enough to determine the contents of them by use of potentiometric titration. The pKa value of brom thymol blue in 80% acetone (9.4) was coincided with each equivalent point of ampicillin, amoxicillin and cephalexin, but those of phenolphthalein, thymolphthalein, thymol blue and brom cresol purple were not. The color change of brom thymol blue at equivalent points was very clear except the case of amoxicillin that the determination of samples in 80% acetone with 0.02 N-KOH solution by the aid of brom thymol blue could be available.