This method is used for the collection and analysis of isocyanates from stationary sources associated with manufacturing processes. This method has been published as a proposed method in the Federal Register but it is not yet promulgated.
Samples are collected isokinetically using a modified Method 5 train consisting of a probe and a series of six impingers. 1-(2-pyridyl)piperazine (1-2PP )in toluene reagent is added to the first three impingers (300, 200, 200mL respectively). The 1-2PP reagent derivatizes the isocyanate compounds in the gas stream. The remaining imginers in the train are an empty impinger, a charcoal impinger and a silica gel impinger.
The probe is rinsed with toluene followed by acetonitrile and added to an amber glass bottle. The conents of the first impinger are weighed and added to the same container along with the toluene followed by acetonitrile rinses of the first impinger. The contents of impingers two through four, after first weighing them, and associated rinses are put into a second amber glass container for shipment to the laboratory. At the laboratory, the contents of the samples are evaporated to dryness, solvent exchanged to acetonitrile, and analyzed by high performance liquid chromatography (HPLC) with ultraviolet/visible (UV/vis) detection to identify and quantitate the target analytes.
Note that there are strict time frames specified for the preparation and use of the 1-2PP reagent. The reagent needs to be used within 10 days of preparation and stored in a refrigerator away from light.
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| Hold Times, Preservatives, Preps, Collection, Analytical & Documentation | |
|---|---|
| Holding Time: | 30 days from sample collection to extraction and 30 days from extraction to analysis. |
| Preservatives: | Keep samples at 4°C and keep protected from light. |
| Required Preps: | 1-(2-pyridyl)piperazine in toluene must kept cold, 4°C, and used within 10 days of preparation. |
| Collection Method: | Modified Method 5 train following EPA Method 207 procedures |
| Analytical Methodology: | HPLC/UV |
| Documentation: | 
207
|
| Analyte | Formula | CAS Number | Detection Limit | |
|---|---|---|---|---|
| Methylene diphenyl isocyanate (MDI) | C15H10N2O2 |
101-68-8 |
112 |
ng/m3 |
| 2,4-Toluene diisocyanate (TDI) | C9H6N2O2 |
584-84-9 |
106 |
ng/m3 |
| Methyl Isocyanate | C2H3NO |
624-83-9 |
228 |
ng/m3 |
| 1,6-Hexamethylene diisocyanate (HDI) | C8H12N2O2 |
822-06-0 |
396 |
ng/m3 |
* 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.