NaH2PO4-H2O, 138.0, CAS 10049-21-5
DEFINITION
Sodium Dihydrogen Phosphate Monohydrate contains not less than 98.0% and not more than 100.5% of NaH2PO4, calculated with reference to the dried substance.
CHARACTERISTICS
Colourless crystals or a white powder.
Very soluble in water; very slightly soluble in ethanol (96%).
Dissolve 10.0 g in sufficient carbon dioxide-free water prepared from distilled water to produce 100 ml (solution S).
IDENTIFICATION
A. Solution S is faintly acid.
B. Solution S yields the reactions characteristic of phosphates.
C. Solution S neutralized with a 10% w/v solution of potassium hydroxide yields reaction A characteristic of sodium salts.
D. Complies with the test for Loss on drying.
TESTS
Acidity : pH of a mixture of 5 ml of solution S and 5 ml of carbon dioxide-free water , 4.2 to 4.5.
Clarity and colour of solution: Solution S is clear and colourless.
Arsenic
: 0.5 g complies with the limit test for arsenic - 2 ppm.
Heavy metals: 12 ml of solution S complies with limit test A for heavy metals. Use lead standard solution (1 ppm Pb) to prepare the standard (10 ppm).
Iron: 10 ml of solution S complies with the limit test for - iron 10 ppm.
Chloride: Dilute 2.5 ml of solution S to 15 ml with water. The resulting solution complies with the limit test for chlorides - 200 ppm.
Sulphate: To 5 ml of solution S add 0.5 ml of hydrochloric acid and dilute to 15 ml with distilled water. The resulting solution complies with the limit test for sulphate - 300 ppm.
Reducing substances: To 5 ml of solution S add 0.25 ml of 0.02M potassium permanganate and 5 ml of 1M sulphuric acid and heat in a water bath for 5 minutes. The solution retains a slight red colour.
Loss on drying: When dried to constant weight at 130°, loses 11.5 to 14.5% of its weight. Use 0.5 g.
NaH2PO4·xH2O
(anhydrous) 119.98
Phosphoric acid, monosodium salt, monohydrate.
Monosodium phosphate monohydrate 137.99 [CAS 10049-21-5]
Phosphoric acid, monosodium salt, dihydrate
Monosodium phosphate dihydrate 156.01 [CAS 13472-35-0]
Anhydrous [CAS 7558-80-7]
Monobasic Sodium Phosphate contains one or two molecules of water of hydration, or is anhydrous. It contains not less than 98.0 percent and not more than 103.0 percent of NaH2PO4, calculated on the anhydrous basis.
Identification— A solution (1 in 20) responds to the tests for Sodium 191 and for Phosphate.
pH: between 4.1 and 4.5, in a solution containing the equivalent of 1.0 g of NaH2PO4·H2O in 20 mL of water.
Water: less than 2.0% (anhydrous form); between 10.0% and 15.0% (monohydrate); between 18.0% and 26.5% (dihydrate).
Insoluble substances— Dissolve a portion equivalent to 10.0 g of NaH2PO4·H2O in 100 mL of hot water, filter through a tarred filtering crucible, wash the insoluble residue with hot water, and dry at 105 for 2 hours: the weight of the residue so obtained does not exceed 20 mg (0.2%).
Chloride— A portion equivalent to 1.0 g of NaH2PO4·H2O shows no more chloride than corresponds to 0.20 mL of 0.020 N hydrochloric acid (0.014%).
Sulfate— A portion equivalent to 0.20 g of NaH2PO4·H2O shows no more sulfate than corresponds to 0.30 mL of 0.020 N sulfuric acid (0.15%).
Aluminum, calcium, and related elements— A solution containing the equivalent of 1.0 g of NaH2PO4·H2O in 10 mL of water does not become turbid when rendered slightly alkaline to litmus paper with 6 N ammonium hydroxide.
Arsenic—the limit is 8 ppm.
Heavy metals—the limit is 0.002%.
Na2HPO4·xH2O (anhydrous) 141.96
Phosphoric acid, disodium salt, dodecahydrate.
Disodium hydrogen phosphate, dodecahydrate 358.14 [CAS 10039-32-4]
Phosphoric acid, disodium salt, heptahydrate.
Disodium hydrogen phosphate heptahydrate 268.07 [CAS 7782-85-6]
Phosphoric acid, disodium salt, dihydrate.
Disodium hydrogen phosphate, dihydrate 177.99 [CAS 10028-24-7]
Phosphoric acid, sodium salt, monohydrate.
Disodium hydrogen phosphate, monohydrate 159.94 [CAS 118830-14-1]
Phosphoric acid, disodium salt, hydrate.
Disodium hydrogen phosphate hydrate [CAS 10140-65-5]
Anhydrous [CAS 7558-79-4]
Dibasic Sodium Phosphate is dried or contains one, two, seven, or twelve molecules of water of hydration. It contains not less than 98.0 percent and not more than 100.5 percent of Na2HPO4, calculated on the dried basis.
Identification— A solution (the equivalent of 1 part of Na2HPO4 in 30) responds to the tests for Sodium and for Phosphate.
Loss on drying— Dry it at 130 to constant weight: the dried form loses not more than 5.0% of its weight, the monohydrate loses between 10.3% and 12.0% of its weight, the dehydrate loses between 18.5% and 21.5% of its weight, the heptahydrate loses between 43.0% and 50.0% of its weight, and the dodecahydrate loses between 55.0% and 64.0% of its weight.
Insoluble substances— Dissolve the equivalent of 5.0 g of Na2HPO4 in 100 mL of hot water, filter through a tarred filtering crucible, wash the insoluble residue with hot water, and dry at 105 for 2 hours: the weight of the residue so obtained does not exceed 20 mg (0.4%).
Chloride— A portion equivalent to 0.5 g of Na2HPO4 shows no more chloride than corresponds to 0.42 mL of 0.020 N hydrochloric acid (0.06%).
Sulfate— A portion equivalent to 0.1 g of Na2HPO4 shows no more sulfate than corresponds to 0.2 mL of 0.020 N sulfuric acid (0.2%).
Arsenic— the limit is 16 ppm.
Heavy metals—the limit is 0.002%.
Monosodium Phosphate; Sodium Biphosphate;
Monosodium Dihydrogen Phosphate
NaH2PO4 Formula wt, anhydrous 119.98
NaH2PO4·H2O Formula wt, monohydrate 137.99
INS: 339(i) CAS: anhydrous [CAS 7558-80-7]
CAS: monohydrate [CAS 10049-21-5]
DESCRIPTION
Sodium Phosphate, Monobasic, is anhydrous or contains one or two molecules of water of hydration and is slightly hygroscopic. The anhydrous form occurs as a white, crystalline powder or granules. The hydrated forms occur as white or transparent crystals or granules. All forms are freely soluble in water, but are insoluble in alcohol. The pH of a 1:100 solution is between 4.1 and 4.7.
Function: Buffer; emulsifier; nutrient.
REQUIREMENTS
Identification: A 1:20 aqueous solution gives positive tests for Phosphate and for Sodium.
Assay: Not less than 98.0% and not more than 103.0% of NaH2:PO4 after drying.
Arsenic: Not more than 3 mg/kg.
Fluoride: Not more than 0.005%.
Insoluble Substances: Not more than 0.2%.
Lead: Not more than 4 mg/kg.
Loss on Drying Anhydrous: Not more than 2.0%; Monohydrate: Between 10.0% and 15.0%; Dihydrate: Between 20.0% and 25.0%.
Na3PO4 (anhydrous) 163.94
Phosphoric acid, trisodium salt, dodecahydrate.
Trisodium phosphate, dodecahydrate 380.13 [CAS 10101-89-0]
Trisodium phosphate, monohydrate 181.96
Anhydrous [CAS 7601-54-9]
Tribasic Sodium Phosphate is anhydrous or contains one to twelve molecules of water of hydration. Na3PO4 (anhydrous) and Na3PO4·H2O (monohydrate) contain not less than 97.0 percent of Na3PO4, calculated on the ignited basis; Na3PO4-12H2O (dodecahydrate) contains not less than 92.0 percent of Na3PO4, calculated on the ignited basis.
Identification— A solution (1 in 20) meets the requirements of the tests for Sodium and for Phosphate.
Loss on ignition— Dry a portion at 100 for 5 hours. Ignite about 2 g, accurately weighed, of the dried sample at about 800 for 30 minutes: calculated on the dried basis, the anhydrous form loses not more than 2.0% of its weight, the monohydrate loses between 8.0% and 11.0% of its weight, and the dodecahydrate loses between 45.0% and 57.0% of its weight.
Insoluble substances— Dissolve a portion equivalent to 10.0 g of anhydrous tribasic sodium phosphate in 100 mL of hot water, and filter through a tarred filtering crucible. [NOTE—Do not use glass.] Wash the insoluble residue with hot water, and dry at 105 for 2 hours: the weight of the residue so obtained does not exceed 20 mg (0.2%).
Arsenic—3 µg per g.
Heavy metals—0.001%.
DESCRIPTION
Sodium Phosphate, Dibasic, occurs as a white, crystalline powder or as granules. It may be anhydrous or contain two molecules of water of hydration. The anhydrous form is hygroscopic. Both forms are freely soluble in water and insoluble in alcohol.
Function: Emulsifier; texturizer; buffer; nutrient.
REQUIREMENTS
Identification: A 1:20 aqueous solution gives positive tests for Phosphate and for Sodium.
Assay: Not less than 98.0% of Na2HPO4 after drying.
Arsenic: Not more than 3 mg/kg.
Fluoride: Not more than 0.005%.
Insoluble Substances: Not more than 0.2%.
Lead: Not more than 4 mg/kg.
Loss on Drying Anhydrous: Not more than 5.0%; Dihydrate: Between 18.0% and 22.0%.
Trisodium Phosphate
Na3PO4 Formula wt, anhydrous 163.94
Na3PO4·12H2O Formula wt, dodecahydrate 380.12
INS: 339(iii) CAS: anhydrous [CAS 7601-54-9]
CAS: dodecahydrate [CAS 10101-89-0]
DESCRIPTION
Sodium Phosphate, Tribasic, occurs as white crystals or granules or as a crystalline material. It may be anhydrous or contain 1 to 12 molecules of water of hydration. The formula for a crystalline material is approximately 4(Na3PO4·12H2O)- NaOH. It is freely soluble in water, but is insoluble in alcohol. The pH of a 1:100 aqueous solution is between 11.5 and 12.5.
Function: Antimicrobial; buffer; emulsifier; nutrient.
REQUIREMENTS
Identification: A 1:20 aqueous solution gives positive tests for Sodium and for Phosphate.
Assay: Anhydrous and Monohydrate: Not less than 97.0% of Na3PO4, calculated on the ignited basis; Dodecahydrate: Not less than 90.0% of Na3PO4, calculated on the ignited basis.
Arsenic: Not more than 3 mg/kg.
Fluoride: Not more than 0.005%.
Insoluble Substances: Not more than 0.2%.
Lead: Not more than 4 mg/kg.
Loss on Ignition Anhydrous: Not more than 2.0%; Monohydrate: Between 8.0% and 11.0%; Dodecahydrate: Between 45.0% and 57.0%.
Sodium Phosphate, Monobasic, Monohydrate
Sodium Dihydrogen Phosphate Monohydrate
NaH2PO4-H2O
Formula Wt 137.99
CAS Number CAS 10049-21-5
REQUIREMENTS
Assay: 98.0-102.0% NaH2PO4 - H2O
pH of a 5% solution: 4.1-4.5 at 25C
MAXIMUM ALLOWABLE
Insoluble matter: 0.01%
Chloride (Cl): 5 ppm
Nitrogen compounds (as N): 0.001%
Sulfate (SO4): 0.003%
Calcium (Ca): 0.005%
Potassium (K): 0.01%
Heavy metals (as Pb): 0.001%
Iron (Fe): 0.001%
Disodium Hydrogen Phosphate Heptahydrate
Na2HPO4-7H2O
Formula Wt 268.07
CAS Number 7782-85-6
REQUIREMENTS
Assay: 98.0-102.0% Na2HPO4-7H2O
pH of a 5% solution: 8.7-9.3 at 25C
MAXIMUM ALLOWABLE
Insoluble matter: 0.005%
Chloride (Cl): 0.001%
Nitrogen compounds (as N): 0.001%
Sulfate (SO4): 0.005%
Heavy metals (as Pb): 0.001%
Iron (Fe): 0.001%
Disodium Hydrogen Phosphate
(suitable for buffer solutions)
Na2HPO4
Formula Wt 141.96
CAS Number 7558-79-4
REQUIREMENTS
Assay: 99.0% Na2HPO4 min
pH of a 5% solution: 8.7-9.3 at 25C
MAXIMUM ALLOWABLE
Insoluble matter: 0.01%
Loss on drying at 105C: 0.2%
Chloride (Cl): 0.002%
Nitrogen compounds (as N): 0.002%
Sulfate (SO4): 0.005%
Heavy metals (as Pb): 0.001%
Iron (Fe): 0.002%
Na3PO4-12H2O
Formula Wt 380.12
CAS Number 10101-89-0
NOTE. This salt, when stored under ordinary conditions, may lose some water of crystallization. Any loss in water will result in an assay of more than 100% Na3PO4-12H2O but does not affect the determination of the relative amount of free alkali present.
REQUIREMENTS
Assay: 98.0-102.0% Na3PO4- 12H2O
MAXIMUM ALLOWABLE
Excess alkali (as NaOH): 2.5%
Insoluble matter: 0.01%
Chloride (Cl): 0.001%
Nitrogen compounds (as N): 0.001%
Sulfate (SO4): 0.01%
Heavy metals (as Pb): 0.001%
Iron (Fe): 0.001%
