Phosphate test
Encyclopedia
This is applicable to laboratory analysis particularly in the determination of water pollution
. Such an analytical test may be either qualitative or quantitative.
A Quantitative method to determine the amount of phosphate
present in samples such as boiler
feedwater is as follows. A measured amount of boiler water is poured into a mixing tube and ammonium heptamolybdate reagent is added. The tube is then stoppered and vigorously shaken. The next step is to add dilute stannous chloride reagent, which has been freshly prepared from concentrated stannous chloride reagent and distilled water, to the mixture in the tube. This will produce a blue color (due to the formation of molybdenum blue
) and the depth of the blue color indicates the amount of phosphate in the boiler water. The absorbance of the blue solution can be measured with a colorimeter
and the concentration of phosphate in the original solution can be calculated. Alternatively, a direct (but approximate) reading of phosphate concentration can be obtained by using a Lovibond comparator
.
This method for phosphate determination is known as Deniges' method .
A simple Qualitative method to determine the presence of phosphate
ions in a sample is as follows. A small amount of the sample is acidified with Concentrated Nitric Acid to which a little ammonium molybdate
is added. The presence of Phosphate Ions is indicated by the formation of a bright yellow layer.
Water pollution
Water pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....
. Such an analytical test may be either qualitative or quantitative.
A Quantitative method to determine the amount of phosphate
Phosphate
A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
present in samples such as boiler
Boiler
A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Materials:...
feedwater is as follows. A measured amount of boiler water is poured into a mixing tube and ammonium heptamolybdate reagent is added. The tube is then stoppered and vigorously shaken. The next step is to add dilute stannous chloride reagent, which has been freshly prepared from concentrated stannous chloride reagent and distilled water, to the mixture in the tube. This will produce a blue color (due to the formation of molybdenum blue
Molybdenum blue
Molybdenum blue is a term applied to:*reduced heteropolymolybdate complexes, polyoxometalates containing Mo, Mo, and a hetero atom such as phosphorus or silicon...
) and the depth of the blue color indicates the amount of phosphate in the boiler water. The absorbance of the blue solution can be measured with a colorimeter
Colorimeter
For articles on Colorimeter see:* Colorimeter * Tristimulus colorimeter...
and the concentration of phosphate in the original solution can be calculated. Alternatively, a direct (but approximate) reading of phosphate concentration can be obtained by using a Lovibond comparator
Lovibond comparator
The Lovibond comparator is a type of colorimeter made in Britain by The Tintometer Ltd. It was invented in the 19th century by Joseph Williams Lovibond and updated versions are still available.-Description:...
.
This method for phosphate determination is known as Deniges' method .
A simple Qualitative method to determine the presence of phosphate
Phosphate
A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
ions in a sample is as follows. A small amount of the sample is acidified with Concentrated Nitric Acid to which a little ammonium molybdate
Ammonium molybdate
Ammonium heptamolybdate is an odourless crystalline compound ranging in colour from white to yellow-green. It is usually encountered as the tetrahydrate, whose chemical formula is 6Mo7O24·4H2O...
is added. The presence of Phosphate Ions is indicated by the formation of a bright yellow layer.