Ethidium bromide is also used during DNA fragment separation by agarose gel electrophoresis. Isoelectric focusing is also the first step in 2-D gel polyacrylamide gel electrophoresis. Nucleic acid sequence can be determined using gel electrophoresis and capillary electrophoresis. Methanol is used as a destaining agent in polyacrylamide gel electrophoresis. Instrumental methods may be used to separate samples using chromatography, electrophoresis or field flow fractionation. Run both samples side by side on a polyacrylamide gel electrophoresis. It is compatible to protein separation by 2D electrophoresis and chromatography in multiplex experiments. It has been tested and recommended for polyacrylamide gel electrophoresis. The limit of resolution for standard agarose gel electrophoresis is around 750 kb. It is essentially a combination of denaturing RNA gel electrophoresis, and a blot. Macromolecule blotting is a process performed after gel electrophoresis. Separation by capillary electrophoresis can be detected by several detection devices. Electroosmotic flow is an essential component in chemical separation techniques, notably capillary electrophoresis. Similarly as in nucleic acid gel electrophoresis, tracking dye is often used. RNA samples are then separated by gel electrophoresis.