Working Modes

Various working modes can be implemented in Prep-SFC. They include pressure and/or composition gradients and simulated moving bed SFC (SMB-SFC). Although these techniques may be useful in theory, they are rarely justified by practice and economics. Pressure or composition gradients can be used for selectivity enhancement and/or elution time reduction when the feedstock components have a large range of retention factors. However, with gradients, one of the advantages of Prep-SFC, the speed, is lost since time is required between the two injections to restore the initial pressure or composition, whereas in isocratic Prep-SFC, one can inject the next sample before the previous one is completely eluted.

SMB-SFC offers some of the theoretical advantages of its related technique SMB-HPLC. In SMB-SFC, the feed introduction and the product removal are continuous. The stationary phase is used more efficiently due to the countercurrent process. In SMB-HPLC the high complexity of the system is counterbalanced by savings on the mobile phase consumption, but this is not the case in SMB-SFC because the eluent is already recycled. However, in SMB-HPLC, the elution is necessarily isocratic while in SMB-SFC it is possible to create a pressure gradient in the system and, in some cases, this advantage can bring a decisive productivity increase.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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