| 词条 | Nitrogen–phosphorus detector |
| 释义 |
The nitrogen–phosphorus detector (NPD) is also known as thermionic specific detector (TSD) is a detector commonly used with gas chromatography, in which thermal energy is used to ionize an analyte.[1][2] It is a type of flame thermionic detector (FTD), the other being the alkali flame-ionization detector (AFID also known as AFD). With this method, nitrogen and phosphorus can be selectively detected with a sensitivity that is 104 times greater than that for carbon.{{citation needed|date=April 2017}} NP-ModeA concentration of hydrogen gas is used such that it is just below the minimum required for ignition. A rubidium or cesium bead, which is mounted over the nozzle, ignites the hydrogen (by acting catalytically), and forms a cold plasma. Excitation of the alkali metal results in ejection of electrons, which in turn are detected as a current flow between an anode and cathode in the chamber. As nitrogen or phosphorus analytes exit the column, they cause a reduction in the work function of the metal bead, resulting in an increase in current. Since the alkali metal bead is consumed over time, it must be replaced regularly . See also
External links1. ^{{cite book|author=Wolfgang Kleiböhmer|title=Environmental Analysis|url=https://books.google.com/books?id=KhkASTftwkUC&pg=PA8|year=2001|publisher=Elsevier|isbn=978-0-444-50021-2|pages=8–}} {{DEFAULTSORT:Nitrogen-phosphorus detector}}{{chromatography-stub}}2. ^{{cite journal|last1=Burgett|first1=Charles A.|last2=Smith|first2=Douglas H.|last3=Bente|first3=H.Bryan|title=The nitrogen-phosphorus detector and its applications in gas chromatography|journal=Journal of Chromatography A|volume=134|issue=1|year=1977|pages=57–64|issn=0021-9673|doi=10.1016/S0021-9673(00)82569-8}} 1 : Gas chromatography |
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