Electron capture detector for

Schematic diagram of an electron capture detector for gas chromatography.

Andreae [712] used four different detectors in his investigations the electron capture detector (for the methylarsines), the quartz cuvette atomic absorption detector (for arsenic and antimony species), the graphite furnace atomic... 

One advantage of gas chromatography is the availability of detectors which respond specifically to certain types of compound. The best known are the electron capture detector for chlorine compounds and the flame photometric detector for nitrogen and phosphorus compounds. If one wants to detect very small molecules such as water or CSj, the standard flame ionisation detector must be replaced by a thermal conductivity detector. 

Most early gas-chromatographic methods for corticosteroid analysis in foods involved use of an OV-17 275 cm column at high temperature and an electron capture detector for separation of the analytes in form of their TMS... 

Sporek, K. F. New type of argon ionisation, helium electron capture detector for gas chromatography. US-At. Energy Comm. Rpt. Conf-650, 809 (1966). — Anal. Abstr. 14, 3715 (1967). 

To determine the residual concentration, the tubes were centrifuged to separate the solids. The centrifugate was then carefully decanted and diluted as appropriate. A 5 ml volume sample was then withdrawn from each vial and extracted with 5 ml of an appropriate solvent (iso-octane for p-DCB, and hexane for 2,4-DCP and NB) and the extract analyzed using a Hewlett-Packard 5B40-A gas chromatograph fitted with an electron capture detector for the p-DCB and the 2,4-DCP and a flame ionization detector for the NB. The resultant concentration versus time plots for p-DCB, 2,4-DCP, and NB on both soils, displayed in Figs. 1, 2, and 3,... 

The FPD does not respond to nitrogen or halogens the AFD does, but much less so than to phosphorus. In those areas, the competition comes primarily from other types of detectors. These are the micro-coulometric and the electrolytic conductivity detectors in the nitrogen and halogen areas and, of course, the electron capture detector for chlorinated hydrocarbons and other electron-attaching compounds. 

The electrolytic conductivity detector has been used to determine organic iodine with excellent success by Westlake (20), as well as chlorine in organochlorine pesticides, operating in the reducing mode to yield HI or HCl as the detected product. The minimum detectability for chlorine is approximately equal to that of the current microcoulometric detection system. Coulson (4, 15) compared the responses of the electrolytic conductivity, microcoulometric, and electron capture detectors for organochlorine compounds in various extractives and found the first two approximately equal and the electron capture detector unsatisfactory because of high background. 

Sufficient volatility for GLC analysis is found for A-acylated esters of amino acids and peptides. Their preparation requires a two-step derivatisation protocol and therefore introduces a potential source of error. There is also anxiety about the impurities that may be introduced in this way. However, this applies to any derivatisation protocol and experienced users of the GLC technique can obtain impressive reproducibility of results, sufficient to match the reliability of the classical Moore and Stein procedure. Flexibility because of the additional range of detectors available for GLC can be useful, e.g. highly sensitive electron-capture detectors for halogenated analytes or amino acids and peptides derivatised with halogen-containing groups. 

With gas chromatography, the most widely used detectors for the analysis of flame retardants are mass spectrometer, electron capture detector for halogenated flame retardants, flame photometric detector, and nitrogen phosphorus detector for organophosphorus FRs. 

Other reagents commonly used include pentafluorobenzyl bromide developed for the analysis of acids, amides and phenols using an electron capture detector for enhanced sensitivity. Organics in surface waters have been successfully analysed by this procedure [47,48]. 

Radioactive heavy elements such as uranium, thorium, or plutonium are used as nuclear fuel radium is used in the radiography of metals and radon is used as a surface label to study surface reactions, as well, in the determination of radium or thorium. Among the lighter isotopes, Ni is used in electron capture detectors for GC analysis, in radiocarbon dating and as a tracer, and tritium in nuclear fusion and as a tracer in the studies of reactions. Many radioactive elements are used as a source of radiation, in medicine to diagnose disease, and for treatment. 

A GC equipped with an electron capture detector. For this evaluation a Tracor 222 Gas Chromatograph equipped with a Nickel 63 High Temperature Electron Capture Detector and a Linearizer was used. 

In a recent modification of such a system, the substances separated on a TLC plate are consecutively vaporized by laser pyrolysis and the resulting products are transported by a suitable carrier gas mixture to an FID or an electron capture detector for quantitation (5a). 

Carrier gas was pure nitrogen with an inlet pressure of 1 atm. and a flow rate of about 30 ml/min. An additional stream of nitrogen at 150 ml/min is passed directly through the detector to reach the optimum value for the detector sensitivity. The response of the electron capture detector for the alkyl leads is greatly affected by the applied potential. In Figure 156 the detector current is plotted for various applied potentials (curve A), and the detector response (curve B) measured in arbitrary units from the peak areas for the same injected amount is also shown. 

Kramer used an electron capture detector for the determination of lead alkyls in petroleum. He claims that a complete analysis for tetramethyllead and tetraethyllead in petrol can be achieved on a column (3 metres) of 10% of Apiezon L on Chromosorb W at 120°C with bromobenzene as internal standard. To separate the mixed alkyls (ethyltrimethyllead, diethyldimethyllead and triethylmethyHead, tetramethyllead and tetraethyllead) it is necessary to combine the above analysis with use of a pre-column (5 cm) of 20% of Carbowax 400 saturated with silver nitrate on Chromosorb W impregnated with 8% of potassium hydroxide. The pre-column retains halogen-containing scavengers in the petrol, which would otherwise mask the ethyltrimethyllead peak. As little as 0.002 g of tetramethyllead and tetraethyllead can be detected in 1 litre of petroleum in a 45 minute analysis. 

Gas chromatography was applied, using selective detectors electron-capture detector for organochlorine compounds, and alkali flame-ionisation detector for organophosphorus compounds. We determined ... 

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