Transport detectors chain

The only detector in Table 14 that is not based on an established analytical technique is the transport detector, which uses one of the GC detectors—FID, ECD, PID, or TID—as the measuring device. It consists of a wire, chain, or belt used to deliver the column effluent to the GC detector, removing the volatile mobile phase enroute. Obviously, the samples run on this system must not be volatile, and for them the FID is a universal detector, which is one reason for its use. 

About the same time as the development of the wire transport detector Haahti and Nikkari [11] described a similar device, more simple in design, that employed a chain loop in place of the wire transport system. A diagram of their apparatus is shown in figure 9. 

Another instrument called the transport detector, used for detection of lipids, proteins or carbohydrates, requires the transport of the column eluent by a moving wire disc, chain or helix. The solvent is evaporated in a furnace and the nonvolatile sample passes into a flame ionization detector (FID) which is detailed later under gas chromatography (GC) wherein FID counts amongst the major detectors. 

A transport detector consists of a carrier that can be for example, a metal chain, wire or disc that continuously passes through the column eluent taking a sample with it as a thin film of mobile phase adhering to its surface. The mobile phase is then... 

The transport system for LC detection was developed to render the detector independent of the choice of mobile phase and allow any solvent to be used without compromise. The column eluent flows over the transporter, which may be a moving wire, chain or disc which takes up all, or a portion of the column eluent. The solvent is then evaporated from the transporter, usually by heating, and the solute is left as a coating on the surface. The transporter then carries the solute into a detection area, where it is sensed by suitable means, such as pyrolysis and subsequently detected by passing the pyrolysis products to a flame ionization detector. The transport detectors, by and large, are not very... 

Potter, G. D., McIntyre, D. R. and Pomeroy, D. (1967). Transport of fallout radionuclides in the grass-to-milk food chain studied with a germanium lithium-drifted detector, page 597 in Symposium on Radioecology, USAEC Report No. CONF-670503, Nelson, D. J. and Evans, F. C., Eds. (National Technical Information Service, Springfield, Virginia). 

Dextrans of high molecular mass also do not have an intrinsic mobility, but are large enough to interact with the migrating sieving medium. The longer the analyte chain, the more intensive the contact with the matrix, and the slower its transport to the detector in this counterelectroosmotic technique (case C in Fig. 17). 

Another group of detectors with sample transfer employs pyrolysis of macromolecules. Column effluent is deposited continuously on the appropriate moving transporter such as a wire, chain, or net. Next, the solvent is evaporated, sample is pyrolyzed and polymer concentration is assessed from the amount of caibon dioxide formed. The problems with cleaning of sample transporter to prevent base line noise and drift prevented broad use of detectors of this kind. The attempts to apply similar principle for monitoring polymer composition by engagement of complete gas chromatography of the fractions so far remained only on the level of laboratoiy experiments. Detection of such kind would provide valuable information on the sample composition, for example for statistical copolymers. There are, however, so far unsolved problems with the dependence of composition of pyrolytic products on presence of the neighboring units in copolymers. 

In 2007 (O Fig. 20.43c), the gas-flow rate was increased to 1,500 ml/min in order to increase the transport efficiency. The temperature gradient was between +32°C and — 164°C. As a result, the Hg deposition region broadened considerably to 14 detectors. Only about 30% of the Rn deposited on the last four detectors. The faster carrier gas transported three observed atoms of Cn further down to detectors at lower temperatures. Chains 3 and 5 were detected in detectors 11 (—21°C) and 14(—39°C). Chain 4 was detected in detector 26 (—124°C). From dew point measurements in the carrier gas, it has to be concluded that the detector surfaces held below — 95° C were covered by a thin ice layer (O Fig. 20.43a-c, vertical lines). Thus, it was concluded that four events (chains 1-3, and 5) are attributable to atoms of element 112 deposited on the gold surface, while chain 4 represents an atom of element 112 deposited on ice. 

The setup shown in Fig. 35 was used for this study. Each side inside the detector array consisted of 32 (1 x 1) cm silicon detectors, one side being coated by a 50 nm thin Au layer. This enabled the detection of a-decay chains with high efficiency and SF events via the detection of coincident fission fragments. A transportation time of about 2 s was achieved by reducing the length of the transport capillary between collection chamber at the accelerator and the... 

The transport of caesium from synthetic aqueous solutions of NaNOs 4 mol L /HN03 1 mol L, spiked with Cs ( 2000 kBq L ) was followed by regular measurement of the decrease of radioactivity in the feed solution by 7 spectrometry analysis, using a detection chain from Intertechnique, equipped with germanium detectors. The counting was always sufficiently long to insure a relative error in the activity measurements of less than 5%. This allowed graphical determination of the constant permeabilities Pm (cm h ) of caesium cation per-... 

If NPs were only capped with citrate ions and the detector electrode surface was covered with alkyl thiols of various lengths, the electron transfer decreased exponentially with an increase in the alkyl chain length for both OS and IS reactions. Thus, the decrease of the overall particle activity (as measured by the magnitude of current transients) was mainly limited by the exponential decay of electron transport from Pt NPs through SAMs to the gold electrode surface (Figure 8.37). 

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