Preparative HPLC trends

There are two major disadvantages to attaching a mass spectrometer to a preparative HPLC system. The first disadvantage is cost. An autoprep system may be purchased for approximately 30,000 but the corresponding MS-prep system costs approximately 150,000. However, because the mass spectrometer is a very sensitive detector and the sample concentration will be very high, an older, possibly redundant mass spectrometer may be redeployed for this task. It should also be noted that the price of mass spectrometers is falling rapidly and this trend appears to be continuing. 

Section II covers the latest trends in reducing sample preparation time, including direct sample infusion/injection and on-line solid phase extraction (SPE). In Section III, we focus on newer trends in stationary phases and how these phases hope to offer different selectivities compared to current CIS-based phases. Section IV briefly provides a few observations on how new detectors are increasing the versatility of HPLC. Finally, in Section V we examine monolithic columns, small particles packed in short columns, high-temperature LC, ultra high-pressure LC, and parallel injection techniques. 

Explanatory figures and tables supplement the text and clarify difficult concepts. Extensive references provide gateways to more focused study. Suitable for undergraduates or new practitioners interested in improving their knowledge on the current status and future trends of HPLC, the book is also a critical resource for researchers looking for solutions to complex separation problems or those who currently use HPLC as either an analytical or a preparative scale tool. 

The trend in liquid chromatography has tended to move away from open column toward what is called high pressure liquid chromatography (HPLC) for analytical as well as preparative work. The change in technique is due to the development of high sensitivity, low dead volume... 

Experiments have been performed on a preparative SFC system using pure CO2 as the mobile phase under significant pressure drop. The retention times, pressure drop characteristics and the mass transfer behaviour were studied. The trends observed differ from the behaviour of HPLC systems. These trends also emphasize the complexity involved in analyzing the data for SFC measurements, which imply in turn greater complexity of the SFC model as compared to standard liquid chromatography model. 

Sensitivity, which is defined as a measure of the minimum amount of sample that can be detected, is often a major concern. Sometimes these problems can be resolved by employing a fluorescence or electrochemical detector and/or preparing a derivative of the analyte. True microbore (i.e. coliunn i.d. < 1.0 mm) HPLC systems can provide gains in sensitivity but these are not used extensively in forensic laboratories mainly because of practical problems associated with reproducibility and short column lifetimes. However, there is a trend towards using narrow-bore columns of 2-3 mm i.d. 

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