Loop Type Interface

Transfer through the loop-type interface (Figure 2) is used for fully concurrent evaporation and is suitable for the analysis of components eluted at oven temperatures above about 150°C. It is the technique most frequently used because of its simplicity: the introduction rate is self-adjusting and the end of the transfer

Figure 2 Loop-type interface for transfer by concurrent eluent evaporation.

can be detected automatically. The maximum volume transferred to date is 20 mL.

The LC eluent passes through a loop mounted in the sample valve with an internal volume chosen to match the volume of the LC window to be transferred. At the end of the fraction, as observed by the LC detector, the valve is switched and the carrier gas pushes the liquid from the loop into the GC pre-column. The temperature of the GC oven is above the solvent boiling point at the carrier gas pressure, which causes the liquid to be stopped as soon as it enters the oven-thermostatted pre-column. The vapours are discharged through the coated pre-column retaining the solutes, driven by the pressure of the carrier gas behind the plug of liquid to be transferred (overflow technique). A separate valve actuated simultaneously with the sample valve feeds the carrier gas either behind the liquid to be transferred or to a T-piece allowing purging of the sample valve during analysis.

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.

Get My Free Ebook


Post a comment