Microchip isotachophoresis (μITP) is a miniaturized version of conventional isotachophoresis (ITP) characterized by low sample and buffer consumption and reduced waste production. μITP with universal conductivity detection is suitable for quantitative analysis of relatively simplified samples that contain analyte(s) at relatively high concentration, e.g., pharmaceutical preparations. Here we describe in detail a principle of μITP in terms of reaching highly precise results. A practical use of μITP is shown on the analyses of various pharmaceutical preparations for content of major constituents including active pharmaceutical ingredients as well as pharmaceutical counterions. The pharmaceuticals are treated only minimally prior to the ITP run on a microchip with coupled channels and sample injection channel with 0.9 μL volume. Developed method is suitable for rapid (analysis time up to 10 min), precise (less than 1% RSD of analyte zone length), and accurate (recovery of 98-101%) determination of major pharmaceutical ingredients using a method of internal standard for data evaluation.
Keywords: Buserelin acetate; Contact conductivity detection; Microchip isotachophoresis; Microchip with coupled channels; N-acetylcysteine; Pharmaceuticals.