High speed HPLC

Figure 9.34 High speed and ultrahigh speed chromatograms of separations of substrate and product from assays of rhinovirus 3c protease. (A) high-speed HPLC separations of the fluorescein-labeled product, peak 1, and labeled substrate, peak 2, which were eluted from a Qs column at 3 mL/min by a 76 24 (v/v) mixture of buffer (SO mAf sodium phosphate and SO mAf sodium acetate in pH 7) and acetonitrile. The peptides were injected in a total volume of 7S fiL and chromatography was performed at ambient temperature. (B and C) Same peaks as above except buffer/acetonitrile ratio was 77 23 (v/v). (D) Ultrahigh-speed chromatogram using an M-pel Cg column at 80°C eluted at 4 mL/min after injection of 1 yuL of sample. (From Hopkins et al., 1991.)...

The time required for most HPLC separations is less than thirty minutes and with some high speed HPLC separations which will be described later these times may be further reduced to less than two minutes. While GLC can often match this performance, neither TLC nor paper chromatography can provide resolution in a comparable time. Apart from the obvious advantage of time saving, relatively labile samples may be rapidly analysed by HPLC before any deterioration has occurred. The problem of sample lability may also be a problem in GLC where thermally labile compounds may be decomposed by the relatively high temperature used in GLC analyses. In contrast, most HPLC separations are carried out at room temperature. 

Monolithic Porous Silica for High Speed HPLC 65... 

MONOLITHIC POROUS SILICA FOR HIGH SPEED HPLC... 

Bartok, T., Szalai, G., Lorincz, Zs., Borcsok, G., and Sagi, F., High-speed RP-HPLC/FL analysis of amino acids after automated two-step derivatization with o-phthaldialdehyde/3-mercaptoproprionic acid and 9-fluorenylmethyl chloroformate, /. Liq. Chromatogr., 17, 4391, 1994. 

Although the condensation of phenol with formaldehyde has been known for more than 100 years, it is only recently that the reaction could be studied in detail. Recent developments in analytical instrumentation like GC, GPC, HPLC, IR spectroscopy and NMR spectroscopy have made it possible for the intermediates involved in such reactions to be characterized and determined (1.-6). In addition, high speed computers can now be used to simulate the complicated multi-component, multi-path kinetic schemes involved in phenol-formaldehyde reactions (6-27) and optimization routines can be used in conjunction with computer-based models for phenol-formaldehyde reactions to estimate, from experimental data, reaction rates for the various processes involved. The combined use of precise analytical data and of computer-based techniques to analyze such data has been very fruitful. 

As mentioned earlier, high-speed separation is necessary to carry out fast, comprehensive 2D HPLC. The polymer monoliths have not been employed in such 2D HPLC, probably because permeability of polymer monoliths is not high enough to allow fast elution of the second dimension (2nd-D) in simple 2D operation, and the gradient cycle at the 2nd-D cannot be so fast to allow online 2D operation without reducing peak capacity at first dimension (lst-D). 

At present, it has only been possible to isolate and identify high concentrations of one compound, isorhamnetin, from pollen of Phleum pretense using high-speed counter-current chromatography. This does not reflect the lack of proper technology, but rather the preparation, time and expense of isolating cryptic and perhaps ephemeral compounds via techniques involving more sophisticated HPLC and mass spectrometry. Consistent with the author s earlier hypothesis that an isorhamnetin class... 

Only a few milligrams of sample is needed for a analytic work, and the determination is complete in a few minutes using modem high-pressure, high-speed equipment. The technique is known as high performance liquid chromatography (HPLC). 

Tea (Camellia sinensis) is one of the most frequently consumed beverages in the world and, consequently, an important agricultural product [168], It has been proved many times that tea may reduce cholesterol level, hypertension, and shows antioxidant and anti-microbial effects [169], Because of its importance, a considerable number of analytical methods have been developed for the separation and quantitative determination of the constituents of tea [170,171]. Thus, the application of high-speed counter-current chromatography [172,173], and HPLC-APCI-MS [174] have been reported. 

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