Wat is het verschil tussen natriummonowaterstoffosfaat, natriummonowaterstoffosfaat dihydraat en natriumdiwaterstoffosfaat dihydraat?

De benaming van de verschillende natriumfosfaten kan voor de nodige verwarring zorgen. Hierbij een oplijsting van de Fagron omschrijving (overeenkomstig met de Ph.Eur.) met het CAS-nummer en de chemische formule:
– Natriummonowaterstoffosfaat = Na2HPO4 = disodium phosphate anhydrous, CAS 7558-79-4
– Natriummonowaterstoffosfaat Dihydraat = Na2HPO4x2H2O = disodium hydrogen phosphate dihydrate, CAS 10028-24-7
– Natriumdiwaterstoffosfaat Dihydraat = NaH2PO4x2H2O = sodium dihydrogen phosphate dihydrate, CAS 13472-35-0

De Martindale geeft volgende informatie:

“Each g of monobasic sodium phosphate (anhydrous)
represents about 8.3 mmol of sodium and of phosphate.
Each g of monobasic sodium phosphate (monohydrate) represents
about 7.2 mmol of sodium and of phosphate. Each g of
monobasic sodium phosphate (dihydrate) represents about
6.4 mmol of sodium and of phosphate.”

“Each g of dibasic sodium phosphate (anhydrous)
represents about 14.1 mmol of sodium and 7.0 mmol of phosphate.
Each g of dibasic sodium phosphate (dihydrate) represents
about 11.2 mmol of sodium and 5.6 mmol of phosphate. Each g
of dibasic sodium phosphate (heptahydrate) represents about
7.5 mmol of sodium and 3.7 mmol of phosphate. Each g of dibasic
sodium phosphate (dodecahydrate) represents about
5.6 mmol of sodium and 2.8 mmol of phosphate.”