Indirect determination of neomycin trisulphate as sulphate by column coupling capillary isotachophoresis.

Anionic capillary isotachophoresis (cITP) with conductometric detection was used for indirect determination of neomycin trisulphate (NMS) as sulphate anion. The following electroylets were tested: leading (LE)--8 mM HCl adjusted with beta-alanine to pH = 3.55, 3 mM bis-tris-propane and 0.2% hydroxyethylcellulose and terminating (TE): 5 mM citric acid; 5 mM formic acid and 5 mM caproic acid. The calibration graphs of sulphates concentration were linear in the range 3.55 to 25.90 mg/dm3 with recoveries between 94.50-99.70%. The method was tested on pharmaceutical preparation Enterogast.