Method 365.4

Phosphorous, Total (Colorimetric, Automated, Block Digester AA II)

This method is for the determination of total phosphorus in drinking water, surface water and domestic and industrial wastes. The sample is heated in the presence of sulfuric acid, potassium sulfate, and mercuric sulfate for 2.5 hours. The residue is cooled, diluted to 25 mL and analyze for phosphorus.

The applicable range of this method is 0.01 to 20 mgP/L. 

(EPA: Office of Water)


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Method Data

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:   Autoanalyzer
Documentation:   365.4

Analyte List*

Analyte Formula CAS Number Detection Limit

* 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.