Injection systems, chromatography

Enzyme immunosensors are used in flow injection systems and Hquid chromatography to provide automated on-line analyses (71—73). These systems are capable of continuously executing the steps involved in the immunoassays, including the binding reactions, washing, and the enzyme reaction, in about 10 minutes. 

A flow scheme for the basic form of ion chromatography is shown in Fig. 7.3, which illustrates the requirements for simple anion analysis. The instrumentation used in IC does not differ significantly from that used in HPLC and the reader is referred to Chapter 8 for details of the types of pump and sample injection system employed. A brief account is given here, however, of the nature of the separator and suppressor columns and of the detectors used in ion chromatography. 

A schematic diagram of a chromatograph for SFC is shown in Figure 6.10. In general, the instrument components are a hybrid of components developed for gas and liquid chromatography that have been subsequently modified for use with supercritical fluids. Thus, the. fluid delivery system is a pump modified for pressure control and the injection system a rotary valve similar to components used in liquid chromatography. The column oven and... 

Cortes, H. J., Campbell, R. M., Himes, R. P., and Pfeiffer, C. D., On-line coupled liquid chromatography and capillary supercritical fluid chromatography large-volume injection system for capillary SFC, ]. Microcol. Sep., 4, 239, 1992. 

Injection systems of a capillary gas chromatography should fulfil two essential requirements (i) the injected amount should not overload the column (ii) the width of the injected sample plug should be small compared with band broadening due to the chromatographic separation. Good injection techniques are those which achieve optimum separation efficiency of the column, allow accurate... 

In some cases, so called direct plasma injection techniques may be used23 83 104 108 instead of protein precipitation for loading plasma samples onto an HPLC/MS/MS system. Some direct plasma injection systems use a column switching technique in which the plasma is loaded onto an extraction column that retains the small molecules. The other plasma components are sent to waste and the flow is switched so that the small molecules are eluted onto an analytical column that connects to the MS/MS.23 83 108 One variation of the column switching method is turbulent flow chromatography commercialized by Cohesive Technologies (now part of Thermo, San Jose, CA).23... 

Microsyringe injection, gas chromatography, 4 611 Microtex polyester fibers, 13 393 Microthermal analysis, recent developments in, 79 577 Micro total analysis system (pTAS),... 

High Performance Liquid Chromatography (HPLC) (Chapter 30) gives an elaborate discussion of theoretical aspects. Instrumentation encompasses the various important components e.g., solvent reservoir and degassing system pressure, flow and temperature pumps and sample injection system ... 

More research has to be done. One area is the influence of non-linearity which causes an extra baseline noise in the correlogram. Injection systems for other kinds of chromatography, in particular GC, have to be developed. The ability to detect very small differences between the solute concentrations in the background and the sample has to be investigated. 

In order to satisfy the spedflcation outlined above, a special interface was developed. TTie detailed design of this interface, the transport system, and over-pressure system have been the subject of a previous pubhcation and a patent application [24]. The system devised for the interface is based on modifications to an injection system presented by Heilbronner et al. [2S] for preparative gas chromatography. A commercial version of the preparative unit was developed by Boer [26]. In this appfication. samples are monitored into the injection vessel which is connected to the gas chromatographic column by a length of stainless steel capillary tubing. 

Murata, K., Mano, N., and Asakawa, N., Development of a large-volume, membrane-based injection system for gradient elution micro-liquid chromatography. Journal of Chromatography A 1106(1-2), 146-151, 2006. 

JA Singleton, LF Stikeleather. High performance liquid chromatography analysis of peanut phospholipids. I. Injection system for simultaneous concentration and separation of phospholipids. J Am Oil Chem Soc 72 481-483, 1995. 

Lariviere, D., Cumming, T. A., Kiser, S., Li, C., and Cornett, R. J., Automated flow injection system using extraction chromatography for the determination of plutonium in urine by inductively couple plasma mass spectrometry, J. Anal. At. Spectrom., 23, 354-360, 2008. 

R. Snell, J. Danielson, et al., Parameters affecting the quantitation performance of cold on-column and splitless injection systems used in capillary gas chromatography, J. Chromatogr. Sci., 25 225-230 (1987). 

Poy, F., Visani, S., and Tenosi, F. (1981). Automatic injection in high-resolution gas chromatography A programmed temperature vaporizer as a general purpose injection system. J. Chromatogr. 217, 81-90. 

Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analyses GC analyses are performed on a WCOT (wall-coated open tubular) polydimethylsiloxane fused silica capillary column (1 fim film thickness, 50m x 0 32mm ID ) Shorter columns for example 25m, or columns with thinner films, for example 0 2/im, may also be used successfully Injection of the silylated sample (2/d) is performed with a moving needle-type injector, other types of capillary GC injection systems may be used after optimization of the concentration and amount of sample to be injected With a 50-m capillary... 

The basic experimental equipment for FFF is, except for the channel and its support, in general identical to the equipment used for liquid chromatography. It is usually composed of a solvent reservoir, a pump, and an injection system the chromatographic column is replaced by the FFF channel, followed by a detector. The FFF channel can require additional supporting devices, such as a centrifuge for sedimentation FFF or a power supply, and other electronic regulation devices for electrical FFF. If necessary, this basic equipment is complemented by a flow meter at the end of the separation system. For special semipreparative purposes, a fraction collector can be attached to the system. 

Oudsema, J. and Poole, C. 1992. Some practical experiences in the use of a solventless injection system for packed column supercritical fluid chromatography. Journal of High Resolution Chromatography, 15 65-70. 

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