The method of manufacture of Glass and Quartz fiber filters is very similar to that of paper filters. Retention efficiency is however, superior to that of paper. Unlike cellulose fibers that swell when wetted, glass fiber filters maintain their dimensional stability and provide a superior chemical resistance and dirt holding capacity as well as biological inertness. Binder free borosilicate glass fiber filters are heat resistant to about 500 ° C. For temperatures, up to 1000 ° C the Quartz (SiO2) microfiber filters are typically used.
Grades of Glass & Quartz Fiber Filters
G/A55 Retention 1.6 µm
General purpose glass fiber filter recommended for air & water pollution monitoring, filtration of protein, bacteria cultures, etc. Recommended for radioimmunoassay’s of weak beta emitters and for food analyses.
G/B140 Retention 1.0 µm
Thick filter offering high wet strength and dirt holding capacity. Good as membrane prefilter, and for industrial waste analyses.
G/C50 Retention 1.2 µm
Recommended for suspended solids analysis of water and wastewater Low absorption make this filter ideal for scintillation counting.
G/F75 Retention 0.7 µm
Often used to collect IgC or other very fine protein precipitates or for clarifying chemically aggressive solutions. Also suitable for analysis of chlorophyll "a".
Q/R100 Retention 1.5 µm
This high purity Quartz (Si02) microfiber filter is specially prefiltered at 900° C for two hours to reduce organic contamination. Recommended for sampling acidic gases at temperatures exceeding 500° C. Also suitable for carbon detection in aqueous studies.
Please note that the micron retention of glass fiber filters does not have a defined pore structure. A nominal rating is usually assigned but this is not an exact value. Nominal value represents an accepted condition, which is a goal or an approximation as opposed to the real value which is always present. Often a nominal value is de facto rather than an exact, typical or average measurement.
| Summary of Trace Metal Content of Glass/Quartz Fiber Filters |
| |
GA55 |
GF75 |
GA100 |
GA200 |
GB100R |
GB140 |
GC50 |
GC90 |
GD120 |
GS25 |
DP70 |
QR100 |
| FE |
100 |
180 |
10 |
8 |
10 |
57 |
73 |
15 |
10 |
15 |
50 |
10 |
| Ni |
<1 |
<1 |
<1 |
<1 |
<1 |
<1 |
<1 |
<1 |
<1 |
<1 |
<1 |
<0.5 |
| Mn |
3.8 |
4 |
<0.5 |
<0.5 |
<0.5 |
1.6 |
2.6 |
<0.5 |
<0.5 |
<0.5 |
2 |
<0.5 |
| Cr |
3 |
6 |
<1 |
<1 |
<1 |
1 |
7 |
<1 |
<1 |
<1 |
3 |
<1 |
| Zn |
14000 |
18000 |
<1 |
<1 |
<1 |
8700 |
7600 |
<1 |
1200 |
<1 |
6000 |
5 |
| Pb |
1 |
3 |
<1 |
<1 |
3 |
<1 |
<1 |
<1 |
<1 |
<1 |
<1 |
<1 |
| Cd |
<0.5 |
<0.5 |
<0.5 |
<0.5 |
<0.5 |
<0.5 |
<0.5 |
<0.5 |
<0.5 |
<0.5 |
<0.5 |
<0.5 |
| Cu |
<1 |
<1 |
<1 |
<1 |
<1 |
<1 |
<1 |
<1 |
<1 |
<1 |
<1 |
<1 |
Test Method:
1) Extract metal contents from filter with Hydrochloric acid and Nitric acid.
2) Dry extracted sample.
3) Re-extract dried sample with Hydrochloric acid.
4) Measure metal content from extraction with Atomic Spectrum Analyzer.
Leaching of components from glass microfiber is a relatively slow process that is dependent on the speed of filtration, the actual fiber diameter, the acid concentration, the temperature of the extraction fluid, and the overall extraction time.
Typical Barium contents in Borosilicate Glass Fiber, expressed as BaO is 5% nominal wt.
