This method is for the determination of specified forms of phosphorus in drinking, surface and saline waters, domestic and industrial wastes. The methods are based on reactions that are specific for the orthophosphate ion and depending on the prescribed pre-treatment of the sample, the various forms of phosphorus may be determined. Ammonium molybdate and antimony potassium tartrate react in an acid medium with dilute solutions of phosphorus to form an antimony-phospho-molybdate complex. This complex is reduced to an intensely blue-colored complex by ascorbic acid. The color is proportional to the phosphorus concentration. Only orthophosphate forms a blue color in this test.
The most commonly measured forms determined by this method are phosphorus and dissolved phosphorus, and orthophosphate and dissolved orthophosphate. Hydrolyzable phosphorus is normally found only in sewage-type samples and insoluble forms of phosphorus are determined by calculation.
No Obligation Quotation for Analytical Services
If you would like us to provide a quote for laboratory analysis, just provide us with as much information as you can about your project (the more, the better) and we'll provide you a quote via email. As you are searching or browsing our Analytical Guide, you'll see the Request-A-Quote icon... just click on it to start the request process.
| Hold Times, Preservatives, Preps, Collection, Analytical & Documentation | |
|---|---|
| Holding Time: | Holding time from sample collection to analysis are: 24 hours for total dissolved phosphorus, 48 hours for dissolved orthophosphate and 28 days for hydrolyzable and total phosphorus. |
| Preservatives: | Preserve with 2 mL concentrated sulfuric acid per liter and refrigerate sample 4°C. |
| Required Preps: | 100 mL HDPE or amber glass bottle |
| Collection Method: | Grab sampling |
| Analytical Methodology: | Spectrophotometer or filter photometer |
| Documentation: | 
365.2
|
| Analyte | Formula | CAS Number | Detection Limit | |
|---|---|---|---|---|
| Phosphorus | P |
7723-14-0 |
0.01 |
mg/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.