Chapter 12 - Introduction - Page 445

Supercritical fluid chromatography (SFC) is a separation technique that uses instrumentation similar to high performance liquid chromatography (HPLC) and a dense compressed gas, almost always carbon dioxide (CO2), as a mobile phase. SFC has long been overshadowed by other chromatographic methods, both HPLC and gas chromatography (GC). Although the advantages of the SFC mobile phase in chromatographic separations are indisputable and will be discussed in detail in Section 1.1, the technique itself has experienced a period of rediscovery only recently, with the introduction of advanced SFC instrumental platforms, new stationary phases, and a different view of the technique itself. Although an old view of SFC was limited to strictly supercritical conditions using only pure CO2 as a mobile phase, which substantially limited the range of compounds that could be analyzed, a modern view of SFC is now represented by CO2-based mobile phases with the addition of organic modifiers, which remarkably extended the range of applications and the versatility of method development. The addition of an organic modifier of course results in a mobile phase that is not in the supercritical state, usually meaning that the pressure is above the critical pressure, but the temperature is below the critical temperature. However, there is a continuity of physicochemical properties between the supercritical and subcritical state (details given in Section 1.1). Therefore, it is now widely accepted that SFC is used as the name of the technique, bearing in mind that the separations are notalways strictly supercritical (Tarafder, 2016; Desfontaine et al., 2015; Nováková et al., 2014).
     During the development of SFC over the years, the technique was given many other names, such as: high temperatureehigh pressure chromatography; dense GC; high pressure gas chromatography (HPGC); solvating gas chromatography; subcritical fluid chromatography; near critical chromatography; convergence chromatography; enhanced fluidity chromatography; HPLC with enhanced fluidity or sometimes even unified chromatography (Lesellier andWest, 2015; Guiochon and Tarafder, 2011; Taylor, 2009). In the most modern interpretations, the name could also be translated as separations facilitated by carbon dioxide. Despite this diversity in terminology, the name SFC is the one most widely accepted by the chromatographic community. It is actually interpreted as a definition of a technique, chromatography with CO2 in the mobile phase, rather than a definition of a fluid state (Lesellier and West, 2015). Indeed, as also suggested by Berger (2015a), SFC should be used as a single acronym that includes all the above stated other names. Similar to ultra-high performance liquid chromatography (UHPLC), the highly efficient and faster variant of SFC taking advantage of sub-2 um particles and dedicated instrumentation is designated as ultra-high performance supercritical fluid chromatography (UHPSFC) (Desfontaine et al., 2015; Nováková et al., 2014).

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

Handbook of Advanced Chromatography / Mass Spectrometry Techniques - Chapter 12 Figure 12

Figure 12.1

Phase diagram of carbon dioxide. Solid (s), liquid (l), and gas state (g). Cp, critical point; Pc, critical pressure; Tc, critical temperature.

Handbook of Advanced Chromatography / Mass Spectrometry Techniques - Chapter 12 Figure 2

Figure 12.2

The number of scientific papers published with the focus on supercritical fluid chromatography (SFC) within the time period 1962-2016. The search was made using the Scifinder database, the keywords “SFC” and “SFC-mass spectrometry (MS),” and all their respective synonyms discussed in Section 1, with the filtration of duplicate results. The bibliography search was made in November 2016.

Handbook of Advanced Chromatography / Mass Spectrometry Techniques - Chapter 12 Figure 3

Figure 12.3

Kinetic performance and normalized generated pressure drop as a function of linear velocity for 1.7 and 3.5 um particles in ultra-high performance liquid chromatography (UHPLC) and ultra-high performance supercritical fluid chromatography (UHPSFC). (A) van Deemter curves for high performance liquid chromatography with 3.5 um particles (blue dots (dark gray in print versions)), UHPLC with 1.7 um particles (red diamonds (gray in print versions)), supercritical fluid chromatography with 3.5 um particles (purple squares (black in print versions)), and UHPSFC with 1.7 um particles (green triangles (light gray in print versions)). (B) Corresponding generated column pressure drops normalized to a 1 m column.

Handbook of Advanced Chromatography / Mass Spectrometry Techniques - Chapter 12 Figure 4

Figure 12.4

Schematic of supercritical fluid chromatography instrumentation.

Handbook of Advanced Chromatography / Mass Spectrometry Techniques - Chapter 12 Figure 5

Figure 12.5

The influence of organic modifier type on ultra-high performance supercritical fluid chromatography (UHPSFC) separations. Chromatograms show separations of the active pharmaceutical ingredient (API) ticagrelor [blue (gray in print versions) 1] and its three impurities (2, 3, 4) on a Torus Diol column (100 mm x 3.0 mm, 1.7 um), with gradient elution 5%-40% of organic modifier in 3 min, flow-rate 1.5 mL/min, temperature 40oC, backpressure regulator 2000 psi, UV detection at 225 nm. ACN, acetonitrile; EtOH, ethanol; MeOH, methanol.

Handbook of Advanced Chromatography / Mass Spectrometry Techniques - Chapter 12 Figure 6

Figure 12.6

Comparison of analysis with and without additives in a ultra-high performance supercritical fluid chromatography method for the separation of vardenafil (API, peak 1) and its six impurities on a charged surface hybrid pentaflurophenyl (CSH PFP) column and for the separation of agomelatine (API, peak 4) and its six impurities on a bridged ethyl hybrid (BEH) column. Gradient elution of 5%-40% was performed with methanol as an organic modifier (A), with methanol + 10 mM ammonium formate (B), and with methanol + 10 mM ammonium acetate (C) in 3 min, flow-rate 1.5 mL/min, temperature 40oC, backpressure regulator 2000 psi, UV detection at 225 nm. NE, not eluted.

Handbook of Advanced Chromatography / Mass Spectrometry Techniques - Chapter 12 Figure 7

Figure 12.7

Plots of analyte retention versus temperature (A) and pressure (B) on a C18 stationary phase, at 2 mL/min with CO2/methanol (95:5) at 210 bar (A) and CO2/methanol (97:3) at 40oC (B).

Reproduced from Zou, W., Dorsey, J.G., Chester, T.L., 2000. Modifier effects on column efficiency in packed-column supercritical fluid chromatography. Anal. Chem. 72, 3620-3626 with permission. Also see the reference for further details of experimental measurements.

Handbook of Advanced Chromatography / Mass Spectrometry Techniques - Chapter 12 Figure 8

Figure 12.8

Model of total MeOH amount entering the eletrospray ionization probe using a prebackpressure regulator splitter with the sheath pump interface as a function of the ultra-high performance supercritical fluid chromatography mobile phase flow-rate (x-axis) and sheath pump flow-rate (y axis) for two different mobile phase CO2/methanol compositions. (A) composition 95:5, (B) 80:20 and three different fixed back-pressures: 120 bar (A1, B1), 150 bar (A2, B2), and 180 bar (A3, B3). MeOH, methanol; MS, mass spectrometry; SFC, supercritical fluid chromatography.

Handbook of Advanced Chromatography / Mass Spectrometry Techniques - Chapter 12 Figure 9

Figure 12.9

Influence of additives on eletrospray ionization-mass spectrometry response.

Handbook of Advanced Chromatography / Mass Spectrometry Techniques - Chapter 12 Figure 10

Figure 12.10

The involvement of supercritical fluid chromatography (SFC) technology in various application and research fields. The search was made using the Scifinder database using the keyword “SFC” with filtration of duplicate results. November 2016.

Handbook of Advanced Chromatography / Mass Spectrometry Techniques - Chapter 12 Figure 11

Figure 12.11

Ultra-high performance supercritical fluid chromatographyemass spectrometry chromatograms of the separation of eight isomers of vitamin E. (A) High-resolution method. (B) High-speed method.

Handbook of Advanced Chromatography / Mass Spectrometry Techniques - Chapter 12 Figure 12

Figure 12.12

Positive-ion ultra-high performance supercritical fluid chromatography/eletrospray ionization mass spectrometry chromatograms of a mixture of lipid class standards (A) and a total lipid extract of porcine brain (B).

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.


Handbook of Advanced Chromatography / Mass Spectrometry Techniques

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Contains both practical and theoretical knowledge, providing core understanding for implementing modern chromatographic and mass spectrometric techniques Presents chapters on the most popular and fastest-growing new techniques being implemented in diverse areas of research.


Handbook of Advanced Chromatography / Mass Spectrometry Techniques

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Handbook of Advanced Chromatography / Mass Spectrometry Techniques

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The Handbook is intended for upper level undergraduate students and graduate students, researchers, technicians, and scientists.It is also well suited for advanced analytical instrumentation students as well as for analysts seeking additional knowledge or a deeper understanding of familiar techniques.


Handbook of Advanced Chromatography / Mass Spectrometry Techniques

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No. of pages: 520
Copyright: © Academic Press and AOCS Press 2017
Published: September 11th 2017
eBook ISBN: 9780128117330
Paperback ISBN: 9780128117323