欧洲标准（EN ISO 3696-1995）

Parameter

Grade1

Grade2

Grade3

pH value at 25 °C  inclusive range

Not applicable

Not applicable

5.0 to 7.5

Electrical conductivity, mS/m at 25 °C, max.

0.01

0.1

0.5

Oxidizable matter Oxygen(O) content mg/l, max

Not applicable

0.08

0.4

Absorbance at 254nm and 1cm optical path length, absorbance units, max.

0.001

0.01

Not specified

Residue after evaporation on heating at 110 °C, mg/kg, max.

Not applicable

1

2

Silica(SiO2) content mg/l, max.

0.01

0.02

Not specified