Phosphorus

 Phosphorus by Ascorbic Acid (By SM 4500-P-E)

Scope:

This method is most suited for measuring phosphorus in water.

Ammonium molybdate and potassium antimonyl tartrate react in acid medium with orthophosphate to form a heteropoly acid-phosphomolybdic acid-that is reduced to intensely colored molybdenum blue by ascorbic acid.

Phosphorus occurs in natural waters and in wastewaters almost solely as phosphates. These are classified as orthophosphates, condensed phosphates (pyro-, meta-, and other polyphosphates), and organically bound phosphates. They occur in solution, in particles or detritus, or in the bodies of aquatic organisms.

These forms of phosphate arise from a variety of sources. Small amounts of orthophosphate or certain condensed phosphates are added to some water supplies during treatment. Larger quantities of the same compounds may be added during laundering or other cleaning, because these materials are major constituents of many commercial cleaning preparations. Phosphates are used extensively in the treatment of boiler waters. Orthophosphates applied to agricultural or residential cultivated land as fertilizers are carried into surface waters with storm runoff and to a lesser extent with melting snow. Organic phosphates are formed primarily by biological processes. They are contributed to sewage by body wastes and food residues, and also may be formed from orthophosphates in biological treatment processes or by receiving-water biota.

Phosphorus is essential to the growth of organisms and can be the nutrient that limits the primary productivity of a body of water. In instances where phosphate is a growth-limiting nutrient, the discharge of raw or treated wastewater, agricultural drainage, or certain industrial wastes to that water may stimulate the growth of photosynthetic aquatic micro- and macroorganisms in nuisance quantities.

Phosphates also occur in bottom sediments and in biological sludges, both as precipitated inorganic forms and incorporated into organic compounds.

– Standard Methods Online – Standard Methods for the Examination of Water and Wastewater

Method Data

Method SM 4500_P_E
Hold Time48 hours (orthophosphate, dissolved), 28 days (Hydrolyzable and Total), 24 hours (Total Dissolved).
PreservationSamples should be collected in plastic or Pyrex glass containers. Samples should be preserved with 2 mL of concentrated sulfuric acid and refrigerated at 4oC.
Sample Volume125 mL HDPE
InstrumentationSpectrometer
Method RefernceSM 4500_P_E

Analyte List

AnalyteFormulaCAS Number
Phophorus, Total
Phophorus, Ortho

*Please contact our project management team for more information about reporting limits and other specific project needs.

Phosphorus

-Phosphorus, All Forms (Colorimetric, Ascorbic Acid, Two Reagent (By EPA 365.3)

Scope:

This method can determine dissolved and total orthophosphate, hydrolyzable phosphate, and phosphorus (all forms) in drinking, surface and saline waters; domestic and industrial wastes.

The sample is pretreated to select the phosphorus forms of interest; the forms are then converted to orthophosphate (which is amenable to the color chemistry of the method). A sample is filtered to select dissolved forms. Polyphosphates are converted to orthophosphate by sulfuric acid hydrolysis. Organic phosphorus is converted to orthophosphate using persulfate digestion.
Ammonium molybdate and antimony potassium tartrate react in an acid medium with dilute solutions of phosphorus to form an antimony-phospho-molybdate complex, which is reduced with ascorbic acid to form an intense blue-colored complex. The absorbance of the complex is measured, and is proportional to the orthophosphate concentration.

 -Methods for the Chemical Analysis of Water and Wastes (MCAWW) (EPA/600/4-79/020)

Method Data

Method E365.3
Hold Time48 hours (orthophosphate, dissolved), 28 days (Hydrolyzable and Total), 24 hours (Total Dissolved).
PreservationSamples should be collected in plastic or Pyrex glass containers. Samples should be preserved with 2 mL of concentrated sulfuric acid and refrigerated at 4oC.
Sample Volume125 mL HDPE
InstrumentationSpectrometer
Method RefernceE365.3

Analyte List

AnalyteFormulaCAS Number
Phophorus, Total
Phophorus, Ortho

*Please contact our project management team for more information about reporting limits and other specific project needs.

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