Injectors for

Schematic diagram of an injector for packed coiumn gas chromatography.

Ga.s Eeeders. Chlorine gas is usually fed from a chlorine cylinder equipped with a pressure gauge, reducing valve, regulating valve, feed-rate indicator, and aspirator-type injector for dissolving the chlorine gas in water. The feeder can be manually, or more desirably automatically, controlled utili2ing continuous amperometric or potentiometric measurement of the free chlorine residual. The chlorine solution is normally introduced into the return line to the filter. 

The efficiency of an ejecdor or jet pump is low, being only a few percent. The head developed by the ejector is also low except in special types. The device has the disadvantage of diluting the fluid pumped by mixing it with the pumping fluid. In steam injectors for boiler feed and similar seiwices in which the heat of the steam is recovered, efficiency is close to 100 percent. 

Together with the techniques described above, other techniques using hot injectors for the transfer of large-volumes in capillary gas chromatography have been developed. Transfer of large-volume solvents in a programmed temperature vaporizing... 

Senorans, R J., Reglero, G., and Herraiz, M., Use of a programmed temperature injector for on-line reversed-phase liquid chromatography-capillary gas chromatography, /. Chromatogr Sci, 33, 446, 1995. 

Several sample preparation techniques are performed inside the inlet system. Large-volume injection can be carried out by a number of methods including programmed temperature vaporisation (PTV). Automated SPE may be interfaced to GC using a PTV injector for large volume injection. SPE-PTV-GC with on-column injection is suited to analysis of thermola-bile compounds. 

Principles and Characteristics Although early published methods using SPE for sample preparation avoided use of GC because of the reported lack of cleanliness of the extraction device, SPE-GC is now a mature technique. Off-line SPE-GC is well documented [62,63] but less attractive, mainly in terms of analyte detectability (only an aliquot of the extract is injected into the chromatograph), precision, miniaturisation and automation, and solvent consumption. The interface of SPE with GC consists of a transfer capillary introduced into a retention gap via an on-column injector. Automated SPE may be interfaced to GC-MS using a PTV injector for large-volume injection [64]. LVI actually is the basic and critical step in any SPE-to-GC transfer of analytes. Suitable solvents for LVI-GC include pentane, hexane, methyl- and ethylacetate, and diethyl or methyl-f-butyl ether. Large-volume PTV permits injection of some 100 iL of sample extract, a 100-fold increase compared to conventional GC injection. Consequently, detection limits can be improved by a factor of 100, without... 

R.J. Schneider, K.F. von Reden and K.H. Purser, A triple isotope injector for accelerator mass spectrometry, Particle Accelerator Conference, 1991, Accelerator Science and Technology, Conference Record of the 1991 IEEE, 878 880 (1991). 

FIGURE 13.7 The loop injector for HPLC, (a) the load positon—the sample is loaded into the loop via a syringe at atmospheric pressure, and (b) the inject position—the mobile phase sweeps the contents of the loop onto the column. 

Sample Injector for HPLC 7725/7725i/9725/9725i, Product Bulletin 209, Rheodyne, Rohnert Park, CA, http //www.rheodyne.com/lit/docs/2320617A.pdf... 

Fion, N., Gobry, V., Jensen, H., Rossier, J. S., and Girault, H. (2002). Integration of a membrane-based desalting step in a microfabricated disposable polymer injector for mass spectrometric protein... 

For the water analysis, automation is clearly best achieved with an auto-injector for the mechanical handhng of the samples coupled with on-hne data capture, using the computer to analyse the peak data. Serious consideration was given to employing the very considerable in house automation experience to construct a purpose-built auto-injector. However, in the interests of a speedy implementation of the automatic system, it was decided to purchase a commercially available auto-injector and to concentrate the laboratory s efforts on the area of on-hne data capture. Interfacing the complete system assembly via a data communications network required the development of a special control device (commhox), which allowed the LGC hardware to run unattended hut provided an audible warning in event of a fault condition. 

Haimovitch, Y., E. Gartenberg, and A. S. Roberts, Jr. 1994. Investigation of rump injector for supersonic mixing enhancement. NASA-CR-4634. 

Legler, B.M., Feed injector for heated fluidised beds, Ghent. Eng. Prog., 63 (2) (1967) 75-82. 

Zhang, C-X. and A. Manz. Narrow sample channel injectors for capillary electrophoresis on microchips. Anal. Chem. 73, 2656-2662 (2001). 

An injector for introducing the sample into the eluent stream and onto the column... 

This included storage tankage, feed lines, proportioning pumps, automatic controls and injector for the introduction of our proprietary chemicals into the boiler. 

Fig. 268. Schematic view showing an arrangement for mixing powder with an injector for producing the explosive oil-in-water emulsion.

One slight disadvantage to this type injector for on-column use is that in temperature-programmed operation the port can generally not be programmed with the column. The port must, therefore, be maintained at a temperature slightly higher than that the column will see in the temperature cycle. 

The specifications of the granulator are as follows output (as referred to souece Mounted on the cover of the enclosure are a source powder feed connection, a ventilating connection, several injectors for feeding agglomerating liquid and an Inspection hole cover. Provision is also made for a mechanism adapted to change the angle of inclination of the plate within 45-60°. 

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