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topic 32635

Testing for Silicates


Is there an in-house method I can use for checking for Silicates in my DI water? Its my understanding that silicate contamination won't show up with typical conductivity/resistivity testing.

Marc Green
Marc Green
anodizer - Idaho


Try concentration by evaporation. Such as boiling a sample until all the water is gone. You will probably need a container with tapered sides to get the sediment localized enough to see/analyze. Use a metal pan with rounded inside corners. The rounded corners are somewhat important in that they promote convection and good mixing (they're also easier to clean). Prop up one corner of the pan so that the water concentrates in the diagonal corner. Heat until only solids are left.

Tom Gallant
- Long Beach, California, USA

First of two simultaneous responses -- 2004

Silica may not show in a conductivity measurement, but whatever it's complexed with should... The most common silicates are potassium and sodium, both of those will affect conductivity. At any rate, Hach makes test kits for just about everything and has one for hardness and one for silicates.

Jeff Watson
Jeff Watson
- Pearland, Texas

Second of two simultaneous responses -- ++++

I appreciate the advice, Tom, but I was actually looking for a ppm determination. I should have been more specific.

Marc Green
Marc Green
anodizer - Idaho

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