This method is for the determination of phenolics in ground water, drinking, surface, and saline waters, and domestic and industrial wastes. This method is based on the coupling of phenol with MBTH in an acid medium using ceric ammonium sulfate as an oxidant. The coupling takes place in the p-position; if this position is occupied, the MBTH (3-methyl-2-benzo-thiazolinone hydrazone hydrochloride) reagent will react at a free o-position. The colors obtained have maximum absorbance from 460 to 595 nm. For phenol and most phenolic mixtures, the absorbance is 520 and 490 nm.
The method is capable of measuring phenolic materials at the 2 µg/L level when the colored end product is extracted and concentrated in a solvent phase using phenol as a standard and is capable of measuring phenolic materials that contain from 50 to 1,000 µg/L in the aqueous phase (without solvent extraction) using different kinds of phenols.
It is not possible to use this method to differentiate between different kinds of phenols.
Most samples require a preliminary distillation to remove interfering materials.
Chlorine and other oxidizing agents that are detected by the liberation of iodine upon acidification in the presence of potassium iodide are removed by adding an excess of ferrous ammonium sufate immediately after sampling. If the chlorine is not removed the phenolic compounds may be partially oxidized and the results may be low.
High concentrations of aldehydes may cause interferences. Phosphate caused a precipitate for form and phosphoric acid should not be used for preservation and glassware should be phosphate free.
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| Hold Times, Preservatives, Preps, Collection, Analytical & Documentation | |
|---|---|
| Holding Time: | 28 days from sample collection to analysis. |
| Preservatives: | Acidify to a pH < 4 with phosphoric acid to inhibit biological degradation. Cool sample to 4°C. |
| Required Preps: | 500 mL amber glass bottle |
| Collection Method: | Grab Sampling |
| Analytical Methodology: | Spectrophotometer |
| Documentation: | 
9067
|
| Analyte | Formula | CAS Number | Detection Limit | |
|---|---|---|---|---|
| Total Phenol | 2 |
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.