The best electrophoresis technique for separating and analyzing the composition of proteins in a complex sample mixture is two-dimensional gel electrophoresis 2D-PAGE . This technique combines two different electrophoresis methods, isoelectric focusing IEF and sodium dodecyl sulfate-polyacrylamide gel electrophoresis SDS-PAGE , to separate proteins based on their isoelectric points pI and molecular weights MW , respectively.In the first dimension, IEF, proteins are separated based on their pI values in a pH gradient. Proteins will migrate to the position where their net charge is zero isoelectric point and stop moving.In the second dimension, SDS-PAGE, the proteins are separated based on their molecular weights. The proteins are denatured and coated with SDS, which imparts a uniform negative charge to the proteins. They are then subjected to an electric field, and the proteins will migrate through the polyacrylamide gel matrix according to their size, with smaller proteins moving faster than larger ones.The combination of these two techniques in 2D-PAGE allows for the separation of proteins in a complex mixture with high resolution, making it easier to analyze their composition. The resulting 2D gel can be further analyzed using techniques such as mass spectrometry, Western blotting, or staining to identify and quantify the proteins present in the sample.