Gel-based proteomics are the most useful method for protein separation, even 
when compared with gel-free proteomics. Proteomic analysis by 2D gel 
electrophoresis (2-DE) with immobilized pH gradients is in turn the best 
approach to large-scale protein-expression screening. Spots visualization is 
pivotal for protein identification by mass spectrometry. Commonly used staining 
methods with excellent mass spectrometry compatibility are coomassie brilliant 
blue (CBB) or fluorescent dyes. In this study, an implementation of 'blue 
silver' colloidal CBB staining, characterized by high sensitivity and immediate 
low background, is discussed. The sensitivity of classical, colloidal and 'blue 
silver' CBB staining methods was compared on monodimensional and 2-DE gels. The 
implementation of the 'blue silver' method performs better, provided the 
physical state of the micelles is respected. An example of a 2-DE of human urine 
treated with combinatorial peptide ligand libraries demonstrates that 
implemented 'blue silver' can evidence the complexity of the sample.