Laboratory grade water
Ultrapure water (UPW) for laboratory
UPW quality guidelines
The ASTM (American Society for Testing and Materials) defines 4 different standard grades for pure water to be used in laboratories.
|
Parameter |
Grade I |
Grade II |
Grade III |
Grade IV |
|
Conductivity µS/cm, 25oC |
0.056 |
1 |
4 |
5 |
|
Resistivity, 25oC MΩ.cm |
18.2 |
1 |
0.25 |
0.20 |
|
TOC (μg/L) |
50 |
50 |
200 |
N/A |
|
Total Silica (μg/L) |
3 |
3 |
500 |
N/A |
|
Sodium (μg/L) |
1 |
5 |
10 |
50 |
|
Chlorides (μg/L) |
1 |
5 |
10 |
50 |
|
pH |
N/A |
N/A |
N/A |
5-8 |
|
Special requirements for reagent Grade Water |
Distillation or equal process followed by ion exchange and 0.2 µm filter |
Distillation or equal process followed by ion exchange |
0.45 µm filter |
|
|
Bacteria (CFU/mL) |
10/1000 |
10/100 |
100/10 |
|
|
Endotoxin (IU/mL) |
<0.03 |
0.25 |
N/A |
|
Note: The values in this table are guidelines provided by ASTM. The guidelines will be revised whenever the laboratory industry develops new linewidths Please consult ASTM website (www.astm.org) for updates on these values.
A well designed UPW system requires a strategic selection of technologies and equipment. Depending on the feed water quality and/or the user requirements, different configurations can be applied.
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