Evaporation injector

A special form of the PTV cold injection system consists of the column and insert connected via a press-fit attachment. Total sample transfer is possible in the same way as the classical PTV injection, but no spht is present to allow flushing of the injection area after evaporation. Injectors of this type can be used only for total sample transfer (e.g. a SPI (septum-equipped programmable injector). Figure 2.69). 

Figure 2.2 Schematic representation of an on-column interface. The eluent leaving the HPLC detector enters the valve and in the stand-hy position, leaves it to go to waste. When the valve is switched on, the eluent is pumped through the transfer line into the inlet of the on-column injector. The liquid floods the capillary wall, thus creating a layer that will retain the solutes. Evaporation occurs from the rear pait of the solvent so refocusing the chromatographic hand. At the end of the transfer, the valve is switched off, and the eluent again flows to waste.

FIGURE 6.9 Horizontal chamber for fully online HPTLC by Nyiredy 1 — evaporator, 2 — diode-array detector, 3 — quartz glass cover plate, 4 — septum, 5 — injector block, 6 — mobile phase, 7 — filter paper, 8 — Teflon chamber, 9 — chromatoplate. (Modified from Nyiredy, Sz., J. Planar Chromatogr. 15, 454-457, 2002.)... 

Chromatographic columns (glass with stopcock and solvent reservoir, 10-mm i.d.) Fused-silica capillary column, DB-1701, 60 m x 0.32-mm i.d., O.lS-qm film thickness (14% cyanopropylphenyl)methylpolysiloxane Varian 3400 gas chromatograph equipped with a temperature-programmed SPI injector, a Varian 8100 autosampler, and a Varian Saturn II lontrap mass spectrometer Centrifuge vials, 10- and 250-mL Evaporation flasks, 100- and 250-mL Separatory funnel, 250-mL... 

The advent of high-resolution capillary gas chromatography (HR-CGC) with on-column injection has resulted in improved GC analysis of polymer additives [92-94]. The solution of the additive mixture is injected directly into the cold end of the capillary column by means of a cold injector. Thus, sample discrimination, the instantaneous evaporation of the sample solvent, is avoided. The nonvaporising, on-column injection combined with very high resolution of the capillary columns allows accurate separation, identification and quantification of additives of complex mixtures. With the solvent venting technique, the sample is introduced into the column without splitting and sample concentrations... 

Figure 2.22 [2.6] demonstrates the method of a cooling circuit with recirculated flow An injector pump operated with just evaporated LN2 aspirates the warmer N2 coming from the condenser and feeds the mixture back in the condenser. The desired condenser temperature can be controlled by a throttle valve. To achieve a uniform temperature distribution, the gas mixture is alternately fed to one or the other end of the condenser. No results of such a system are given. 

As nowadays wine making has factory dimensions, the need for a rapid method is important, so a flow injection techniqne for liqnid-solid extraction coupled to an HPLC was developed [368]. The target analytes were extracted from wine in a continuous way by means of a minicolumn packed with C18, the elntion was carried ont by means of acid water (pH 2) and acetonirile, then the solvent was evaporated by nitrogen stream on-line to a HPLC injector. Malvidin-3-glucoside, cyaniding-3-glncosyde, and peonidin-3-glncoside antocyanins were determined in a more rapid, accurate, and sensitive way than with the traditional methods. 

In addition to the use of the LC-GC interface (Figure 2), 1 ml fractions were manually collected and analyzed by gas chromatograph using the autosampler. The concentrated fractions were also evaporated using a slow stream of nitrogen and analyzed each fraction by GC-MS using a SGE on-column injector. 

ATOMIZED PROPELLANTS. For those combustors in which the propellants persist in droplet form for a large percentage of the length of the chamber, it is apparent that the available propellant must be represented as a heterogeneous mass of liquid and vapor in which the vapor concentration will vary with distance from the injector. As Figure 4 shows that the vapor concentration can be determined from droplet evaporation considerations, the equation for available propellant W can be written in terms of the square of the relative droplet diameter s = (D/D0)2 ... 

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