DNPH procedure

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The DNPH method is a measuring method for the determination of aldehydes and ketones in air and exhaust gases. The discontinuous process is used for immission and emission measurements.

Structure, procedure and use

For the determination of volatile aldehydes and ketones, these are reacted with dinitrophenylhydrazine (DNPH). This can be done either by absorption in an acidic solution containing DNPH (gas washing bottle method) or by adsorption on an adsorbent covered with DNPH (cartridge method).

With both methods, the resulting 2,4-dinitrophenylhydrazones can then be determined individually using high-performance liquid chromatography and UV detection. With the gas washing bottle method, the absorption solution can be analyzed directly; with the cartridge method, elution with acetonitrile is necessary.

A passive collector is used to determine aldehydes and ketones in indoor air . This is provided with cellulose paper that is covered with silica gel . The silica gel is coated with DNPH and phosphoric acid . As with the cartridge method, elution with acetonitrile followed by high-performance liquid chromatography takes place after sampling.

In the ring test the DNPH method and the 3-methyl-2-benzothiazolinone hydrazone working delivered MBTH method equivalent results. Compared to the MBTH method, the DNPH method is selective with regard to the individual components.

The DNPH procedure was repeated with the standard ISO 16000, part 4 and the VDI Guidelines VDI 3862 sheet 2, sheet 3 and sheet 7 standardized . Among other things, it is used to measure emissions in combustion systems and internal combustion engines.

If the emissions contain urotropine , an excessively high level of formaldehyde is detected. In this case another method should be used.

literature

  • VDI 3862 Part 2: 2000-12 Measurement of gaseous emissions; Measuring aliphatic and aromatic aldehydes and ketones by the DNPH method; Gas washing bottle method (Gaseous emission measurement; Measurement of aliphatic and aromatic aldeydes and ketones by DNPH method; Impinger method). Beuth Verlag, Berlin. ( Summary and table of contents online )

Individual evidence

  1. ^ A b Franz Joseph Dreyhaupt (Ed.): VDI-Lexikon Umwelttechnik. VDI-Verlag Düsseldorf 1994, ISBN 3-18-400891-6 , p. 515.
  2. ↑ Wolfgang Schreier: Emissions measurements on gas engines. In: Hazardous substances - cleanliness. Air . 69, No. 1/2, 2009, ISSN  0949-8036 , pp. 25-30.
  3. ↑ VDI 3862 sheet 2: 2000-12 measurement of gaseous emissions; Measuring aliphatic and aromatic aldehydes and ketones by the DNPH method; Gas washing bottle method (Gaseous emission measurement; Measurement of aliphatic and aromatic aldeydes and ketones by DNPH method; Impinger method). Beuth Verlag, Berlin, p. 5.
  4. ↑ a b VDI 3862 sheet 3: 2000-12 measurement of gaseous emissions; Measuring aliphatic and aromatic aldehydes and ketones by the DNPH method; Cartridge method (Gaseous emission measurement; Measurement of aliphatic and aromatic aldeydes and ketones by DNPH method; Cartridges method). Beuth Verlag, Berlin, pp. 4-5.
  5. ↑ DIN ISO 16000-4: 2012-11 indoor air pollution ; Part 4: Determination of formaldehyde; Sampling with passive samplers (ISO 16000-4: 2011). Beuth Verlag, Berlin, p. 10.
  6. ↑ VDI 3862 sheet 1: 1990-12 measurement of gaseous emissions; Measurement of aliphatic aldehydes (C 1 to C 3 ) using the MBTH method (Gaseous emission measurement; measurement of aliphatic aldehydes (C 1 to C 3 ) MBTH method). Beuth Verlag, Berlin, p. 2.
  7. ↑ Heiko Hayen, Martin Vogel, Uwe Karst: Recent developments in the determination of formaldehyde in air samples using derivatizing agents. In: Hazardous substances - cleanliness. Air. 63, No. 7/8, 2003, ISSN  0949-8036 , pp. 295-298.