EN 1205:2005 is a European Standard published by CEN (Technical Committee CEN/TC 164) that applies to disodium dihydrogen pyrophosphate (Na2H2P2O7, also known as sodium acid pyrophosphate or SAPP) when used for the treatment of water intended for human consumption. The standard describes product identification and physical properties, specifies purity and impurity limits, and lists the corresponding test and sampling methods. It also provides guidance on labelling, transport and storage. EN 1205:2005 supersedes EN 1205:1997 and clarifies that national regulations and approvals remain applicable in EU/EFTA member states.
Key topics and technical requirements
- Identification and properties
- Chemical formula: Na2H2P2O7; relative molecular mass: 222.0; CAS 7758-16-9; EINECS 231‑835‑0
- Commercial forms: white powder (solid) or clear aqueous solution
- Solubility ≈ 130 g/L at 25 °C; 1% solution pH ≈ 4.0; solid melting point ≈ 650 °C
- Purity and composition
- Phosphate content (as P2O5): (64 ± 1.0) % (dry basis)
- Sodium content (as Na2O): (28 ± 0.5) % (dry basis)
- Impurity limits (mg/kg dry product)
- Sulfate (SO4²–): max. 500
- Fluoride (F–): max. 10
- Trace elements and chemical parameters (mg/kg dry product)
- Antimony, Arsenic, Cadmium, Selenium: max. 3 each
- Chromium, Lead, Nickel: max. 10 each
- Cyanide: max. 5; Mercury: max. 1
- Test and sampling methods
- Labelling / regulatory note
- Conformity with EN 1205:2005 does not replace national approvals; use is subject to national authority regulation.
- Water utilities and municipal drinking-water authorities specifying chemical products for potable water treatment
- Chemical manufacturers and suppliers producing or labelling disodium dihydrogen pyrophosphate for water treatment
- Analytical laboratories conducting conformity testing, sampling and trace-element analysis
- Regulators and procurement officers assessing product suitability against purity and impurity limits
Related standards and references
This standard is essential when specifying, testing or purchasing disodium dihydrogen pyrophosphate for drinking-water applications and for ensuring trace impurity limits and approved analytical methods are followed.