Gel-to-gel variation is a major problem in two-dimensional (2D) gel
electrophoresis. Vertical and horizontal comparative fluorescence gel
electrophoresis (v/hCoFGE) were recently introduced to improve the
reproducibility of protein spot assignment. protein analytes were overlaid
with a reference grid control of the first dimension,pI(x-direction), applied
amphoteric azo dyes for this purpose completing the CoFGE toolkit.