Conductivity measures the amount of charged ions in water that can conduct electricity. Silicates (SiO₄⁴-), on the other hand, are weakly dissociated anions. In water, they are often present as uncharged or only weakly charged species, especially at neutral pH values. As a result, they contribute only minimally to conductivity.
The most important reasons why conductivity does not measure silicates:
- Low dissociation: silicates only partially dissociate into ions in water. The majority remain as uncharged molecules.
- Weak conductivity: Even the dissociated silicate ions have a low charge density and hardly contribute to the electrical conductivity.
- Selectivity of conductivity measurement: Conductivity mainly detects strongly charged ions such as Na⁺, Cl-, SO₄²-, which effectively conduct electricity, but not weakly charged or uncharged substances such as silicates.
To measure silicates in water, we at HeylNeomeris use the Testomat 808 SIO2, an online water analyzer designed specifically for use in clinical environments. Alternatively, the PPM 150 hand-held measuring device is available for quick on-site analysis.
Neomeris PPM150 Portable Photometer with USB interface The PPM 150 multiparameter handheld photometer for the determination of chemical water constituents is equipped with 9 LEDs in the wavelength range from 380 to 810 nm. The device has the following performance profile: Flexible for many reagents from different manufacturers Software for documentation and for creating calibration curves Internal method memory for a maximum of 150 calibration curves Storage of up to 1,000 data records in the internal data memory; each data record is documented: Date, time, wavelength, reagent used, measurement result, measurement number Wired data transfer via integrated USB interface between photometer and PC/laptop Pre-parameterised with the measurement curves of all parameters listed below In addition to the parameters specified for the respective industry solution, the reagents listed below are available for photometric determination using the PPM 150. The corresponding data is available for a large number of other reagents from various manufacturers and can be compiled individually for the photometer on request. Parameter Measuring range Order number Ammonium 0,01-2,0 410681 Chlorine (free) 0-1,5 410521 Chlorine (total) 0-1,5 410521 Chlorine (bound) 0-1,5 410521 Chlorine dioxide 0-2,8 410525 Chloride 0-70 410527 Chromat 0-2,5 410533 Requirements Low 0-1,5 410548 Eisen High 0-10,0 410545 Hydrazin 0-1,0 410557 Copper 0-4,0 410563 Nitrite 0-1,0 410691 Phosphat 0-20,0 410593 Silicate 0-10,0 410623 Sulfit 0-20,0 410635 Hydrogen peroxide 0-20,0 410643
