When an LC-like detector such as a UV detector is used, a two-pump system is favoured. The two pumps are operated in the pressure control mode, and the inlet and the outlet pressures are controlled independently, so that the pressure drop across the column can be controlled.

When a GC-like detector such as a flame ionization detector (FID) is used, the two-pump system is not applicable and a single-pump system is used. A low dead-volume restrictor is generally employed in this case to maintain an appropriate pressure and to avoid additional dispersion of analytes.

The oven should be capable of negative as well as positive temperature programming. Negative temperature programming is useful in SFC, as shown below.

Open tubular capillary columns with various immobilized stationary phases are commercially available. The smallest diameter commercially available is around 50 |im. On the other hand, packing materials with 3-50 |im particle diameters for LC can be used for packed capillary columns, and fused silica tubing or glass-lined stainless-steel tubing are available. Conventional packed columns (1-5 mm i.d.) are still used most often in SFC, but they do not fit into the compromise that constitutes universal chromatography.

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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