Silica
Silica
Silica_PT_ULow_HTB_Eng_Ody.fm Page 3 of 6
Interferences
Sample Collection, Storage, and Preservation
Use only plastic containers with tight-fitting closures. Do not use glass
containers; they will contaminate the sample with silica. Soak sampling
containers with a solution made of one part Molybdate 3 Reagent
(Cat. No. 1995-03) to 50 parts of high quality deionized water of low silica
concentration. Fill completely and let stand for several hours. Rinse thoroughly
with low-level silica water, drain and close. Repeat this cleaning periodically.
Allow the sample stream to flow for 1–2 minutes before collection. Do not adjust
the flow during the sampling period as this may introduce particulates. Rinse
the container well with sample before collecting the portion for analysis.
Analyze as soon as possible.
17. Wait at least
15 seconds, then pour the
contents of the second
flask into the Pour-Thru
Cell.
After the flow stops,
touch
Read.
Results will appear in
µg/L SiO
2
.
18. Flush the Pour-Thru
Cell with at least 50 mL of
deionized water
immediately after use.
Interfering Substance Interference Levels and Treatments
Color Eliminated by zeroing the instrument with the original sample (follow procedure).
Iron Interferes at high levels.
pH (extreme) Adjust pH to less than 7. See Section 3.3 Interferences on page 41.
Phosphate (PO
4
3–
) Interferes at levels greater than 50 mg/L PO
4
3–
.
Sulfides Interfere at all levels.
Turbidity Eliminated by zeroing the instrument with the original sample (follow procedure).
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