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.
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| 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 | 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.