Background

Phosphorus is one of the most important elements to life. It is part of ATP, the most crucial molecule for the transfer and storage of cellular energy. Phosphorus is also part of the nucleic acids which form the blueprint of life.

In natural water and wastewaters, phosphorus exists almost exclusively in the form of phosphate. Phosphate also exists in different forms, such as orthophosphate, condensed phosphate, and organically bound phosphate. Phosphates may enter the water from agricultural runoff, or biological and industrial wastes. Orthophosphates are a part of many fertilizers used in agriculture. It is carries into water adjacent to farm lands by storm runoff. Phosphate is also a major ingredient in detergents. Before the current stringent regulations, people who lived near water often had their drains empty into the water source. The restrictions placed on water pollution and the amount of phosphates added to detergents and other cleaning products have helped to diminish the devastation and algal bloom can cause in an aquatic ecosystem. Currently, though, it is estimated that detergent contributes 50% of the phosphate in domestic sewage.

Phosphate also occurs naturally in rock formations. It is most often found as part of the mineral apatite. It is easily leached from these rock formations and ends up in different aquifers. Like so many other elements that make up living organisms, it is also added to the water supply by the decompositions of dead organisms. For this reason, sediment on the bottom of lakes and rivers contain dissolved organic phosphate. A certain amount of phosphates are also added in municipal and industrial waste treatment processes to control corrosion.

Although a small amount of phosphate is necessary for most plants and animals, too much phosphate in water can contribute to eutrophication, especially when large amounts of nitrogen are also present. Phosphate has been found to be the limiting growth factor in primary producers. Green plants require phosphate to carry out functions that enable them to grow and reproduce. Phosphate is quickly utilized when it is available in the aquatic environment. When it is in greater concentration than needed, phosphate can cause an algal bloom. This rapid growth of algae and phytoplankton causes the complete depletion of any dissolved oxygen in a body of water. Algae reproduce and die very rapidly, and the decomposition of their remains depletes dissolved oxygen. This often can wipe out the population of organisms in a body of water.

Because a certain amount of phosphate is so important, there are a few different mechanisms that have evolved in times of phosphate depletion. Alkaline phosphatase is an extracellular enzyme released by phytoplankton that has the ability to free phosphate bound to organic molecules. A mechanism used by algae to save phosphate for a time of depletion is luxury consumption. Phytoplankton store polyphosphate granules that can be used when needed.

Phosphate does not pose a direct threat to human health. What is of most concern to the environmental scientist is the oxygen depletion that can result from an algal bloom. Places to test for phosphate concentration are water sources near farmland, and anyplace where it may be suspected that untreated wastewater is being dumped.

It has been determined that phosphate levels below 5mg/L are considered inadequate for normal plant growth and primary production. Levels of greater than 10mg/L are considered overabundant and will lead to the consequences stated.

 

Test Method

This Snap Test kit utilizes the highly sensitive and specific molybdenum blue method of orthophosphate concentration determination. In the presence of orthophosphate, and acidic solution of ammonium molybdate is reduced to a blue colored solution by the reducing agent stannous chloride.

Phosphorus in the form of soluble pyrophosphates, metaphosphates, or polyphosphates will not respond to the test unless the sample is first boiled with acid.

 

Cautions & Safety Information

Read MSDS (material safety data sheet) before performing this test procedure

If this product is used as directed, the user will not came in contact with the chemical reagents. If contact does occur, flush skin or eyes with water. If swallowed, call a physician.

As an added precaution, we recommend that the user wear safety glasses when performing this test.

Dispose of used test ampoules as instructed in MSDS.

 

Test Procedure

1. Fill the sample cup to the 25ml mark with your water sample.

2. Add 2 drops of the activator solution to the sample cup. Stir briefly.

3. Place the tapered tip of the test ampoule into one of the four depressions in the bottom of the sample cup. Snap the tip by squeezing the test ampoule toward the side of the cup. The sample will fill the ampoule and begin to mix with the reagent inside. Note: A small gas bubble will remain in the ampoule to facilitate mixing.

4. Remove the fluid filled ampoule from the sample cup. Mix the contents of the ampoule by inverting it several time, allowing the bubble to ravel from end to end inside.

5. Wipe all liquid from the exterior of the ampoule and wait two minutes.

6. Use the comparator to determine the level of orthophosphate in the sample.

 

Using the Comparator

The comparator (1-10ppm) should be illuminated by a strong white light from directly above. Place the filled test ampoule between the color standards for viewing. It is important that you compare your ampoule by placing it on both sides of the standard tube before concluding that it is darker, lighter, or equal to the standard.