Echelle plasma emission detector

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The Echelle plasma emission detector ( EPED for short ) is a component used in gas chromatography , an apparatus-based chemical-analytical process. Gas chromatography devices with EPED are used for element-specific detection of sulfur- or halogen-containing analytes .

Layout and function

The detector consists of a plasma cell and an echelle spectrometer; H. an echelle grating that splits the radiation emitted by the plasma into the various wavelengths and a two-dimensional CCD sensor with which the intensities of the radiation are measured at the different wavelengths.

The plasma cell consists of a quartz glass tube with an internal diameter of around 0.7 mm . In addition to the column eluate from the gas chromatograph in the carrier gas helium , a reaction gas mixture consisting of oxygen and hydrogen is passed through it . A pulsed high frequency is applied via external electrodes and a helium plasma is generated in which the analytes are atomized. The present heteroatoms are put into an electronically excited state. When relaxing , these emit radiation that is characteristic of the respective element. The two-dimensional splitting on the Echelle grating enables high wavelength precision and exact element allocation. The intensity of the emitted radiation is proportional to the concentration of the analyte present.

Application area

With the EPED it is possible to determine compounds with heteroatoms such as sulfur , fluorine , chlorine , bromine and iodine simultaneously and independently of one another . The area of ​​application therefore focuses primarily on the analysis of halogenated hydrocarbons , brominated flame retardants , (poly) fluorinated compounds ( perfluorinated surfactants , fluorotelomer alcohols ) and sulfur-containing pesticides . These can be analyzed and quantified unaffected by the heteroatom-free matrix with comparatively little effort during sample preparation.

See also

literature

  • E. Strigl: Highly selective GC detection: determination of halogen and sulfur compounds , GIT-Labor, 3/2010 pp. 210–212 full text, PDF .

Individual evidence

  1. ↑ L. Gruber, J. Ewender, D. Fiedler, M. Schlummer, F. Welle, E. Strigl: The newly developed Plasma Emission Detector with Echelle Spectrometer (EPED) in combination with GC as a tool to analyze the emission of unknown fluorinated substances from consumer products and food contact materials. Full text (PDF; 424 kB) .