Method TO-5

Determination of Aldehydes/Ketones in Ambient Air by HPLC


This method is used for the collection and analysis of individual aldehydes and ketones in ambient air.  Ambient air is drawn through a midget impinger containing dinitrophenylhydrazine (DNPH) reagent.  Aldehydes and ketones present in the sample form stable DNPH derivities and are analyzed by HPLC.

The sample is collected using a rotameter, pump and three midget impingers.  The first two impingers are filled with 10mL of DNPH reagent and 10mL of isooctane.  The third impinger contains silica gel.  After sample collection, the  contents of the first iminger are emptied into a glass bottle.  The contents of the second impinger which is then added to the glass bottle.  Mark the volume level on the bottle before shipment and refrigerate samples.

The sample is extracted, concentrated to dryness and dissolved in methanol and analyzed by HPLC with UV detection.

Acetone is a known contaminant of the DNPH reagent and cannot be accurately measured using this method.

Method TO-11A which uses a DNPH cartridge can also be used to measure aldehydes/ketones.


(EPA 600/4-89-017)

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Method Data

Hold Times, Preservatives, Preps, Collection, Analytical & Documentation
Holding Time:   DNPH reagent must be prepared no more than 48 hours before use. Keep samples refrigerated after collection until analysis.
Preservatives:   Store in can containing 1-2 inches of granular charcoal, refrigerate (4 °C)
Required Preps:   50mL Glass bottle with Teflon-lined lid
Collection Method:   Midget impinger train
Analytical Methodology:   HPLC/UV
Documentation:   TO-5

Analyte List*

Analyte Formula CAS Number Detection Limit
Benzaldehyde
C7H6O
100-52-7
0.05
 µg
p-Tolualdehyde
C8H8O
104-87-0
0.05
 µg
Acrolein
C3H4O
107-02-8
0.05
 µg
Valeraldehyde (Pentanal)
C5H10O
110-62-3
0.05
 µg
Propionaldehyde (Propanal)
C3H6O
123-38-6
0.05
 µg
Crotonaldehyde
C4H6O
123-73-9
0.05
 µg
Formaldehyde
CH2O
50-00-0
0.05
 µg
o-Tolualdehyde
C8H8O
529-20-4
0.05
 µg
m-Tolualdehyde
C8H8O
620-23-5
0.05
 µg
Hexaldehyde (hexanal)
C6H12O
66-25-1
0.05
 µg
Acetone
C3H6O
67-64-1
0.05
 µg
Acetaldehyde
C2H4O
75-07-0
0.05
 µg
Isobutyraldehyde
C4H8O
78-84-2
0.05
 µg
Methyl ethyl ketone (2-Butanone)
C4H8O
78-93-3
0.05
 µg

* The analytes and detection limits listed for each method represent the typical detection limits and analytes reported for that particular method. Keep in mind that analyte lists may vary from laboratory to laboratory. Detection limits may also vary from lab to lab and are dependent upon the sample size, matrix, and any interferences that may be present in the sample.