ISO 3696:1987 distinguishes between three degrees of purity for water for analytical purposes in laboratories.
|pH value at 25°C||–||–||5.0 up to 7.0|
|Conductivity at 25 °C [µS/cm]||0.1||1.0||5.0|
|Oxidizable matter, oxygen content [mg/l, max.]||–||0.08||0.4|
|Absorption at 254 nm and a lenght of 1 cm (absorption units, max.)||0.001||0.01||–|
|Residue after evaporation by heating to 110 °C (mg/kg, max.)||–||1||2|
|Silicon content [mg/l, max.]||0.01||0.02||–|
This institute defined the quality requirements of water for clinical laboratories. The regulations that were valid up to 2006 (NCCL types 1, 2 and 3) but were then invalidated by the requirement that water must be suitable for the intended usage. Only the degree of purity of so-called “Clinical laboratory reagent water” (CLRW) is described.
|Resistance [MΩ x cm]||10|
|TOC [ppb]||< 500|
|Bacteria [CFU/ml]||< 10|
|Particle Content||Inline 0.2 µm-filter|
The ASTM D1193-06 (2011) deals with the requirements for chemical analyses and physical tests.