This method is for the determination of free carbonyl compounds (aldehydes and ketones) in aqueous matrices by derivatization with 2,4-dinitrophenylhydrazine (DNPH). Samples are analyzed using high performance liquid chromatography (HPLC) with ultraviolet/visible (UV/vis) detection. This method replaces SW-846 Method 8315.
Approximately 100mLs of sample is buffered to a pH of 3.0. If the analysis is for formaldehyde only, the sample is buffered to a pH of 5.0. The sample is then deriviatized with DNPH and analyzed.
Formaldehyde is a common contaminant of the DNPH reagent, therefore, the DNPH reagent should be checked on a regular basis for contamination. The method allows <25 mg/L of the target analytes. The DNPH reagents should be stored at 4°C, in the dark, with minimum headspace and the solutions may be stable for up to 6 weeks.
All samples should be shipped and stored at 4°C. There is a 3 day holding time from collection until the derivatization/extraction of the sample. All derivatized sample extracts should be analyzed within 3 days of the sample preparation.
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| Hold Times, Preservatives, Preps, Collection, Analytical & Documentation | |
|---|---|
| Holding Time: | Samples must be derivatized within 3 days of collection and analyzed within 3 days of derivatization. |
| Preservatives: | Cool to 4°C. |
| Required Preps: | 500mL amber glass bottle. |
| Collection Method: | Grab sampling |
| Analytical Methodology: | HPLC with UV/Vis detection |
| Documentation: | 
8315A
|
| Analyte | Formula | CAS Number | Detection Limit | |
|---|---|---|---|---|
| Cyclohexanone | C6H10O |
108-94-1 |
20 |
µg/L |
| Valeraldehyde (Pentanal) | C5H10O |
110-62-3 |
20 |
µg/L |
| Glutaraldehyde | C5H8O2 |
111-30-8 |
20 |
µg/L |
| Heptylaldehyde (heptanal) | C7H14O |
111-71-7 |
20 |
µg/L |
| Decaldehyde (decanal) | C10H20O |
112-31-2 |
20 |
µg/L |
| Propionaldehyde (Propanal) | C3H6O |
123-38-6 |
20 |
µg/L |
| Butyraldehyde (Butanal) | C4H8O |
123-72-8 |
20 |
µg/L |
| Crotonaldehyde | C4H6O |
123-73-9 |
20 |
µg/L |
| Octanal | C8H16O |
124-13-0 |
20 |
µg/L |
| Nonanal | C9H18O |
124-19-6 |
20 |
µg/L |
| Formaldehyde | CH2O |
50-00-0 |
20 |
µg/L |
| m-Tolualdehyde | C8H8O |
620-23-5 |
20 |
µg/L |
| Hexaldehyde (hexanal) | C6H12O |
66-25-1 |
20 |
µg/L |
| Acetaldehyde | C2H4O |
75-07-0 |
50 |
µg/L |
* 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.