Ultra-Fast Chromatography

The effect of running at constant pressure is to greatly speed up the linear velocity at the beginning of the run where the peaks are well separated. Later in the run, when the temperature is high, the velocity is lower allowing more dwell time on the column for the later peaks which elute close together. 

The search for innovative solutions to increase the limiting peak capacities in GC came up many years ago with two-dimensional separations. The development of instrumental techniques focussed in the beginning on the transfer of specific peak regions of interest, the unresolved humps , to a second separation column. This technique, widely known as heart cutting, found many successful applications in solving critical research oriented projects but its use was not widespread in routine laboratories. 

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Some groups have evaluated ultra-fast chromatography separations (so-called ballistic, pseudo-chromatography) in order to provide a snapshot of the sample purity [42, 43], The major drawback to the ballistic chromatography technique is that column resolution is reduced when operating at these sub-optimal linear velocities. Also, the pseudo-chromatography approach is best suited to applications where purity assessment is secondary to rapid compound prohling. 

The special instrumentation required for ultra-fast chromatography comprises a dedicated ultra-fast column module (UFM), see Figure 2.129, or low-thermal-mass device (LTM), comprising a specially assembled fused silica column for... 

Facchetti, R. and Cadoppi, A. (2005) Ultra Fast Chromatography A Viable Solution for the Separation of Essential Oil Samples. The Column, November 2005, 8-11,... 

The current status of chromatography is shown in Table 10.25. Since reducing separation time is a major issue, there is a pronounced trend toward shorter columns filled with small particles. The current trends for lower flow (micro- and nano-LC) columns, and great strides to achieve (ultra-) fast chromatographic... 

Stoll, D.R., Cohen, J.D., Carr, P.W. (2006). Fast, comprehensive online two-dimensional high performance liquid chromatography through the use of high temperature ultra-fast gradient elution reversed-phase hquid chromatography. J. Chromatogr. A 1122 (1-2), 123-137. 

Romanyshyn L. Tiller P. Ultra-short columns and ballistic gradients considerations for ultra-fast chromatographic liquid chromatographic-tandem mass spectrometric analysis. Journal of Chromatography A, 2001,928,41-51. 

Romanyshyn, L. Tiller, P. R. Alvaro, R. Pereira, A. Hop, C. E. Ultra-fast gradient vs fast isocratic chromatography in bioanalytical quantification by liquid chromatography/ tandem mass spectrometry. Rapid Commun Mass Spectrom 2001, 15, 313-319. 

Klejdus B, Lojkova L, Lapcik O, Koblovska J and Kuban V, Supercritical fluid extraction of isoflavones from biological samples with ultra-fast high-performance liquid chromatography/mass spectrometry. J Sep Sci 28 1334-1346 (2005). 

Romanyshyn, L. Tiller, PR. Alvaro, P. Pereira,A. Cornells,E.C.A. Ultra-fast Gradient vs. Fast Isocratic Chromatography in Bioanalytical Quantification by Liquid Chromatography/Tandem Mass Spectrometry, Rapid Commun. Mass Spectrom. 15, 313-319 (2001). 

Tiller, RR. and Romanyshyn, L.A., Implications of matrix effects in ultra-fast gradient or fast isocratic liquid chromatography with mass spectrometry in drug discovery, Rapid Commun. Mass Spectrom., 16(2), 92, 2002. 

Wainhaus, S. et al., Ultra fast liquid chromatography-MS/MS for pharmacokinetic and metabolic profiling within drug discovery, Am. Drug Discov., 2(1), 6, 2007. 

Yan B, Znqo J, Brown JS, Blackwell J, Carr PW. High temperature ultra fast liquid chromatography. Anal Chem 2000 72 1253-1262... 

Eatih, O. 2010. Quantitation of heterocychc aromatic amines in ready to eat meatballs by ultra fast liquid chromatography. Food Chem. 126 2010-2016. 

Batycka, M., Inglis, N.F, Cook, K., Adam, A., Fraser-Pitt, D Smith, D.G.E., Main, L Lubben, A., Kessler, B.M. (2006) Ultra-fast Tandem Mass Spectrometry Scanning Combined with Monolithic Column Liquid Chromatography Increases Throughput in Proteomic Analysis. Rapid Commun. Mass Spectrom. 20 2074-2080. 

Bicchi, C., C. Brunelli, C. Cordero, P. Rubiolo, M. Galli, and A. Sironi, 2005. High-speed gas chromatography with direct resistively-heated column (ultra fast module-GC) -separation measure (5) and other chromatographic parameters under different analysis conditions for samples of different complexities and volatilities, 1071 3. 

Figure 2.130 Column wrapping detail with heating element and temperature sensor for ultra-fast capillary chromatography.

Because quadrupole-based MS instruments collect data sequentially, their ability to decrease SIM and SRM dwell times to 1 ms remains of interest for the monitoring of a significant number of compounds. However, TOF-based instruments acquire data over a wide mass range, and an acquisition rate of 10-20 spectra/s is sufficient for UHPLC experiments because their peak widths at baseline would never be less than 1 s. Currently, the only interest in faster TOF/MS devices concerns coupling to fast or ultra-fast gas chromatography (GC), which has peak widths at the baseline as small as dozens of milliseconds. 

Specialists distingnish three kinds of faster GC techniques fast, very fast, and ultra fast. Their characteristics are presented in Table 1.1. The ultra fast GC is difficult to perform and imposes many constraints. The main sectors that use fast chromatography are the same ones that use traditional GC, for example for analyzing organic micropollutants and essential oils. As Table 1.1 demonstrates, the time gains can be spectacular. 

The latest innovation is the introduction of ultra-thin silica layers. These layers are only 10 xm thick (compared to 200-250 pm in conventional plates) and are not based on granular adsorbents but consist of monolithic silica. Ultra-thin layer chromatography (UTLC) plates offer a unique combination of short migration distances, fast development times and extremely low solvent consumption. The absence of silica particles allows UTLC silica gel layers to be manufactured without any sort of binders, that are normally needed to stabilise silica particles at the glass support surface. UTLC plates will significantly reduce analysis time, solvent consumption and increase sensitivity in both qualitative and quantitative applications (Table 4.35). Miniaturised planar chromatography will rival other microanalytical techniques. 

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