High-speed injector

A high-speed injector is required in supercritical fluid chromatography. This is to prevent loss of pressure during the injection process. 

Solid-Phase Microextraction. Solid-phase microextraction (SPME), used as a sample introduction technique for high speed gc, utilizes small-diameter fused-silica fibers coated with polymeric stationary phase for sample extraction and concentration (33). The trapped analyte can be liberated by thermal desorption. By using a specially designed dedicated injector, the desorption process can be shortened to a fraction of a second, producing an injection band narrow enough for high speed gc. A modified system has been investigated for the analysis of volatile compounds listed in EPA Method 624. Separation of all 28 compounds by ion trap mass spectrometric detector is achieved in less than 150 seconds. 

Evidently, at high-speed GPC separations, very severe requirements are laid also on the other parts of the apparatus, in the first instance on the pumping system, injector and volumeters. The constancy of all operational variables must be more rigorously controlled, as well. On the other hand, the application of smaller columns means material savings, especially as the amount of both sample and eluent is substantially reduced. 

These parameters may be easily measured with high temporal and spatial resolution by high-speed laser diagnostics (e.g., planar LIF of fuel and vapor) and diffraction-extinction techniques. These diagnostic tools have been used to study spray structures of automotive injectors and to investigate spray behavior by analyzing these structures [55, 59, 60]. 

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