“…Therefore, to increase the sensitivity when using the miniaturized technique, some approaches have been proposed to overcome the mentioned drawbacks, allowing analysts to applying nano-LC to real samples analysis. Among the different solutions proposed, the use of (1) sensitive and specific detectors, e.g., MS, (2) UV-detector cells with extended path length, (3) on-column focusing (Mills et al, 1997;Cappiello et al, 2002;Rocco et al, 2013b;Buonasera et al, 2009), and (4) pre-and/or 2D-column preconcentration are currently employed (Vissers et al, 1997).…”