This method is for the determination of chlorinated acids (herbicides) in drinking waters. It is also applicable for reagent water and finished ground and surface waters. Forty milliliters of samples is adjusted to pH < 12 with 4N sodium hydroxide to hydrolize derivitives. After derivitization the sample is acidified to a pH < 1 and extracted with methyl-tert-butyl-ether (MTBE). The chlorinated acids are converted to the methyl ester form by derivitizing with diazomethane. The esters are then analyzed by fast capillary gas chromatography with an electron capture detector (ECD). Any positive detects are confirmed with analysis using a second column.
Phthalate esters are the source of major interferences with the elctron capture detector. Avoid use of any flexible tubing during sample collection.
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| Hold Times, Preservatives, Preps, Collection, Analytical & Documentation | |
|---|---|
| Holding Time: | 14 day from collection to extraction and 21 days from extraction to analysis. Samples must be cooled and not exceed 10°C during shipment. Store samples at ≤6°C. Protect samples from light until extraction. |
| Preservatives: | If residual chlorine is present, add sodium sulfite crystals (~2mg/40mL) to the sample bottle prior to collection. |
| Required Preps: | 40mL Amber glass bottle with Teflon-lined cap |
| Collection Method: | Grab sampling |
| Analytical Methodology: | GC/ECD |
| Documentation: | 
515.4
|
| Analyte | Formula | CAS Number | Detection Limit | |
|---|---|---|---|---|
| Dichloroprop | C9H8Cl2O3 |
120-36-5 |
0.433 |
µg/L |
| Chloramben | C7H5Cl2NO2 |
133-90-4 |
0.057 |
µg/L |
| Dicamba | C8H6Cl2O3 |
1918-00-9 |
0.032 |
µg/L |
| Picloram | C6H3Cl3N2O2 |
1918-02-1 |
0.076 |
µg/L |
| Bentazon | C10H12N2O3S |
25057-89-0 |
0.064 |
µg/L |
| Acifluorfen | C14H7ClF3NO5 |
50594-66-6 |
0.307 |
µg/L |
| 3,5-Dichlorobenzoic acid | C7H4O2Cl2 |
51-36-5 |
0.212 |
µg/L |
| Dalapon | C3H4Cl2O2 |
75-99-0 |
0.054 |
µg/L |
| Pentachlorophenol | C6HCl5O |
87-86-5 |
0.014 |
µg/L |
| Dinoseb | C10H12N2O5 |
88-85-7 |
0.166 |
µg/L |
| 2,4,5-TP (Silvex) | C9H7Cl3O3 |
93-72-1 |
0.033 |
µg/L |
| 2,4,5-T | C8H5Cl3O3 |
93-76-5 |
0.024 |
µg/L |
| 2,4-D | C8H6Cl2O3 |
94-75-7 |
0.055 |
µg/L |
| 2,4-DB | C10H10Cl2O3 |
94-82-6 |
0.246 |
µg/L |
| Quinclorac | C10H5Cl2NO2 |
84087-01-4 |
0.08 |
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.