Comprehensive chromatographic separations in proteomics

In such a complicated field as proteomic analysis, scientists are more and more challenged in implementing separation systems capable to provide enhanced separation power, as well as sensitivity of detection for adequate identification and, to a lesser extent, quantification of the separated compounds. To address such issues, several combinations of different separation modes have been investigated in comprehensive liquid chromatographic platforms, in which the entire sample eluted from the first dimension is subjected to a secondary chromatographic separation. The different applications exploited for comprehensive LC analysis of intact or digested proteins are the focus of this review, in which advantages and disadvantages of the different columns combinations, interfaces, and operating modes are pointed out. The combination with mass spectrometry as part of the total system is stressed, and illustrated in more detail. Theoretical concerns and practical requirements will be briefly discussed, as well.