Restrictors backpressure regulator

The main components of a typical SF extractor are a gas supply, a high pressure pump, a controller used to pressurize the gas, a temperature controlled oven, an extraction vessel, a restrictor (backpressure regulator) and a collection device (Figure 2.21). 

Figure 7.2.4 Experimental set-up used for SFC-NMR experiments (a) modifier pump (b) SFC pump (c) CO2 cylinder with dip-tube (d) cryostat (e) GC oven with mixing chamber and separation column (f) injection valve (g) UV detector (h) NMR magnet (i) backpressure regulator or restrictor (j) hardware control unit...

Fig. 1 Two general styles for interfacing SFC to API sources are depicted. In (A), the SFC column effluent is directed entirely into the API source. In some systems, the restriction apparatus is a simple transfer tube restriction used for low flow experiments. In others, a variable restrictor or backpressure regulator is used between the outlet and the source. In the configuration used by Pinkston and Baker,the restriction apparatus is a series of tees to add a coaxial flow of nebulizing gas, an electrospray buffer sheath flow, and another to introduce liquid from a syringe pump to regulate mobile phase pressure. In (B), a direct interface is shown in which a split directs a fraction of the mobile phase flow toward the API source, while the remainder is sent to waste through a backpressure regulator or some controlled restriction to maintain system pressure.

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