Straight away, platinum appeals to the imagination. We immediately think of expensive jewels. And that's right. Platinum is often used in jewellery because it is harmless, virtually non-oxidizing and easy to process because it is so soft.
Cobalt is a somewhat less well-known element and was not very popular for a long time because of toxic compounds with arsenic. Miners used to think that goblins (German for gnomes) put the toxic stuff in the mines. Hence the name.
Potentiometry and temperature
The standard hydrogen electrode (SHE) consists of platinum that is immersed in a hydrochloric acid solution and around which hydrogen gas bubbles. This electrode forms the basis and the official zero point for potentiometry, the measurement of potential differences. All electrodes, including the glass electrode for pH measurement, are compared with the SHE to determine their potential.
A more common application for platinum is the measurement of temperature with the very well-known PT100 or PT1000. These are electrical resistors that have exactly 100 or 1000 ohms at 0 ° C. The resistance changes with heating or cooling and can thus be used as a temperature measurement. PT100 and PT1000 are real industrial standards. The electronic modules to convert the resistance measurement to temperature can of course be found in the ELSCOLAB range.
The colour of a liquid or the lack thereof, is an important quality parameter. Various liquids have a yellowish colour. This yellow colouration is used for quality determination of surface water and wastewater.
At the end of the 19th century, the American Allen Hazen developed a colour scale for potable water discolouration in areas with a lot of peat in the soil. The American Public Health Association adjusted the scale and since then this has been called the APHA scale. The basis of this colour scale is a dilution series of platinum and cobalt salts. The standard solution contains exactly 500 mg of platinum-cobalt per litre. This solution has colour number 500 APHA. The ASTM standard D1209 describes the standard test method for the colour of clear solutions (Platinum cobalt scale).
Colour measurement has been one of the most important pillars of ELSCOLAB since its establishment. That’s why the APHA scale is frequently used. We measure the colour of different products using different devices in almost all industries and applications, both in laboratories and inline on a production scale.
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