Sodium phosphate is a generic term for the salts of sodium hydroxide and phosphoric acid

Phosphoric acid

Phosphoric acid, also known as orthophosphoric acid or phosphoric acid, is a mineral acid having the chemical formula H3PO4. Orthophosphoric acid molecules can combine with themselves to form a variety of compounds which are also referred to as phosphoric acids, but in a more general way...

. They are:

• sodium dihydrogen phosphate
  Monosodium phosphate
  Monosodium phosphate , also known as anhydrous monobasic sodium phosphate is a chemical compound of sodium with a phosphate counterion. It is used as a laxative and, in combination with other sodium phosphates, as a pH buffer....
  
  , commonly termed monosodium phosphate, (NaH₂PO₄), is also known as "sodium phosphate, monobasic".
• disodium hydrogen phosphate
  Disodium phosphate
  Disodium hydrogen phosphate is a sodium salt of phosphoric acid. It is a white powder that is highly hygroscopic and water soluble. It is therefore used commercially as an anti-caking additive in powdered products. It is also known as disodium hydrogen orthophosphate, sodium hydrogen phosphate...
  
  , commonly termed disodium phosphate, (Na₂HPO₄) is also known as "sodium phosphate, dibasic".
• Trisodium phosphate
  Trisodium phosphate
  Trisodium phosphate is a cleaning agent, food additive, stain remover and degreaser. It is a white, granular or crystalline solid, highly soluble in water producing an alkaline solution....
  
  , commonly shortened to just sodium phosphate, (Na₃PO₄), is also known as "sodium phosphate, tribasic".
• sodium aluminium phosphate
  Sodium aluminium phosphate
  Sodium aluminium phosphate is a chemical used in food processing. It is synthetically produced from aluminium, phosphoric acid and sodium hydroxide. As a food additive is has the E number E541....
  
  , (Na₈Al₂(OH)₂(PO₄)₄).

Sodium phosphates are often used as meat preservatives, as an alternative to sodium nitrite

Sodium nitrite

Sodium nitrite is the inorganic compound with the chemical formula NaNO2. It is a white to slight yellowish crystalline powder that is very soluble in water and is hygroscopic...

. This is common in canned meats.

Risk

Oral sodium phosphates for bowel preparation for colonoscopy

Colonoscopy

Colonoscopy is the endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus. It may provide a visual diagnosis and grants the opportunity for biopsy or removal of suspected...

 may in some individuals carry a risk of kidney injury under the form of phosphate nephropathy. There are several oral phosphate formulations which are prepared extemporaneously. Oral phosphate prep drugs have been withdrawn in the United States, although evidence of causality is equivocal. Since safe and effective replacements for phosphate puratives are available, several authors have recommended general disuse of oral phosphates.