Chapter 9 - Introduction - Page 309

Nano-liquid chromatography (nano-LC), first introduced by Karlsson and Novotny in 1988, is a miniaturized liquid chromatographic technique where the separation of analytes takes place on a capillary column containing selected stationary phases (SPs). Even though a standard definition of nano-LC has not been accordingly fixed, this name is assigned to those techniques employing capillaries of internal diameter (I.D.) < 100 um and flow rates in the range 25-800 nL/min. In contrast, capillary liquid chromatography (CLC) makes use of 150-500 um I.D. columns and flow rates in the range 1-20 uL/min.
In nano-LC, the relatively low flow rate represents an interesting advantage over conventional techniques, allowing the perfect coupling with mass spectrometry (MS). In addition, costs are reduced because of the limited use of mobile phases, and consequently, low waste makes this technique ecofriendly. In addition, peak dilution during the chromatographic run is reduced with an increase of mass sensitivity. Finally high efficiency, good resolution, and short analysis times are currently obtained (Karlsson and Novotny, 1988; Szumski and Buszewski, 2002; Herna´ndez-Borges et al., 2007; Fanali et al., 2013a, 2015b). Because of its features and advantages, nano-LC has been applied mainly in analytical chemistry for the analysis of a large number of compounds currently investigated in various fields such as proteomics, pharmaceutical, chiral, food and beverages, environmental, forensic and toxicology, etc.
The aim of this chapter is to illustrate the state of the art of nano-LC by reviewing fundamental principles, the instrumentation currently used, and its advantages over conventional high-performance liquid chromatography (HPLC). Specific selected applications of nano-LC are also reported and described. They cover not only the chromatographic separation of several compounds but also the validation of the method and quantitative aspects, both applied to the analysis of real samples of different origin. Although the use of microchips seems to be very promising, this technique will be only mentioned just to illustrate its potentiality in analytical chemistry.

Click on the thumbnail graphics below to access the original full-size figure.

Figure 9.1

Scheme of the preparation of a capillary column using the “slurry” packing procedure. I: packing of the SP; II: flushing with water; III: inlet frit preparation with a heated wire; IV: outlet frit preparation; VI: removal of excess SP; VII: removal of the polyimide external layer for the detection window.

Reproduced from Fanali, C., Asensio-Ramos, M., Hernández-Borges, J., Rocco, A., Fanali, S., 2011. Nano-liquid chromatographic separations. In: Byrdwell, W.C., Holčapek, M. (Eds.), Extreme Chromatography: Faster, Hotter, Smaller. American Oil Chemists’ Society (AOCS), Urbana, IL, USA, pp. 301-380.

Figure 9.2

Scheme of capillary liquid chromatography coupled with nuclear magnetic resonance (NMR) through a continuous flow NMR probe. HPLC, high-performance liquid chromatography.

Figure 9.3

Schematic representation of a column-switching system coupled with mass spectrometry (MS). ESI, electrospray ionization.

Figure 9.4

Scheme of a multidimensional approach utilizing a global N-glycome characterization followed by parallel analysis of deglycosylated and glycosylated peptides with orthogonal fractionation.

Reprinted from Parker, B.L., Thaysen-Andersen, M., Solis, N., Scott, N.E., Larsen, M.R., Graham, M.E., Packer, N.H., Cordwell, S.J., 2013. Site-specific glycan-peptide analysis for determination of N glycoproteome heterogeneity. J. Proteome Res. 12, 5791-5800 with permission from ACS Publications.

Figure 9.5

Schematic illustration of two versions of the original high performance liquid chromatography chip.

Reprinted from Zhao, C., Wu, Z., Xue, G., Wang, J., Zhao, Y., Xu, Z., Lin, D., Herbert, G., Chang, Y., Cai, K., Xu, G., 2011. Ultra-high capacity liquid chromatography chip/quadrupole time-of-flight mass spectrometry for pharmaceutical analysis. J. Chromatogr. A 1218, 3669-3674 with permission from Elsevier.

Figure 9.6

Nano-liquid chromatography-electrospray ionization mass spectrometry base peak chromatogram of the anthocyanin content of a commercial blueberry juice.

Reprinted from Fanali, C., Dugo, L., D’Orazio, G., Lirangi, M., Dachá, M., Dugo, P., Mondello, L., 2011b. Analysis of anthocyanins in commercial fruit juices by using nano-liquid chromatography-electrospray-mass spectrometry and high-performance liquid chromatography with UV-vis detector. J. Sep. Sci. 34, 150-159 with permission from Wiley-VCH.

Overview of the Contents:

The Handbook of Advanced Chromatography /Mass Spectrometry Techniques is a compendium of new and advanced analytical techniques that have been developed in recent years for analysis of all types of molecules in a variety of complex matrices, from foods to fuel to pharmaceuticals and more. Focusing on areas that are becoming widely used or growing rapidly, this is a comprehensive volume that describes both theoretical and practical aspects of advanced methods for analysis. Written by authors who have published the foundational works in the field, the chapters have an emphasis on lipids, but reach a broader audience by including advanced analytical techniques applied to a variety of fields.

Chapter 9 - Introduction - Page 309

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Figure 9.1

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