AHMT procedure

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The AHMT method is a measuring method for determining the formaldehyde content in gases. The discontinuous method is used to measure emissions .

Structure, procedure and use

For the determination of formaldehyde, a partial flow of the loaded exhaust gas is passed through a washing bottle . There the aldehydes contained react in a strongly alkaline aqueous medium with 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT) to form a colorless intermediate product. This reacts with atmospheric oxygen to form a purple tetrazine derivative , the concentration of which can be measured photometrically .

The reaction of AHMT with aldehydes cannot be evaluated in an acidic medium. A large proportion of acidic gases in the exhaust gas, in particular carbon dioxide , increases the reaction time.

Compared to the DNPH procedure and the MBTH procedure , the AHMT procedure has no cross-sensitivities to urotropine . However, it is not selective for formaldehyde. No direct statements on formaldehyde emissions are possible with the AHMT process.

The AHMT process was standardized with the VDI guideline VDI 3862 Part 4 . It is used, among other things, to measure emissions from smoking plants , animal carcass recycling plants and combustion engines.

literature

  • VDI 3862 Part 4: 2001-05 Measurement of gaseous emissions; Measurement of formaldehyde according to the AHMT method (Gaseous emission measurement; Measurement of formaldehyde by the AHMT method). Beuth Verlag, Berlin. ( Summary and table of contents online )

Individual evidence

  1. ↑ a b Wolfgang Schreier: Emissions measurements on gas engines. In: Hazardous substances - cleanliness. Air . 69, No. 1/2, 2009, ISSN  0949-8036 , pp. 25-30.
  2. ↑ Helmut König: Photometric aldehyde determination. In: Dust - cleanliness. Air . 45, No. 9, 1985, ISSN  0949-8036 , pp. 423-425.
  3. ↑ Hans-Günter Haub, Sigrid Mühlhauser, Franz-Josef Müller, Arno Gardziella: Measurement of emissions during the curing of phenolic resins. In: Dust - cleanliness. Air. 48, No. 4, 1988, ISSN  0949-8036 , pp. 145-149.
  4. ↑ Torsten Neumann, Gennadi Zikoridse, Peter Gamer, Torsten Moczigemba: Formaldehyde from biogas CHP - current status for some systems installed in Saxony and Thuringia. In: Hazardous substances - cleanliness. Air. 71, No. 5, 2011, ISSN  0949-8036 , pp. 227-230.