Silver

Silver

At times, silver is used in the disinfection of pools and spas, as well as in water filters. Small quantities of silver act as a bacteriostatic agent preventing the growth of bacteria. The presence of silver in water is also indicative of pollution, mainly from film manufacturers, film processors, and surface finishers. Silver levels are closely monitored since its presence in drinking water can cause discoloration of the skin, eyes, and mucous membranes.

Hanna Instruments offers a wide variety of instrumentation for measuring silver. Products include portable and benchtop pH/ISE meters that use a solid-state silver Ion-Selective Electrode (ISE) for direct measurement. The silver ISE can be used as an indicator following the progress of a halide titration with silver nitrate. The argentometric titration for chloride is a very common measurement when determining the sodium content in food. In this titration sodium chloride reacts with silver nitrate to form silver chloride precipitate. When there is no more chloride for the silver nitrate to react with then free silver ions are present. The silver/sulfide ISE is used to determine the stoichiometric endpoint.

In addition to potentiometric devices, Hanna offers a photometric method that uses reagents to determine the silver concentration in a sample. This method uses an adaptation of the 1-(2-pyridylazo)-2-naphthol (PAN) method to measure silver concentrations up to 1.000 mg/L (ppm). The method is pre-programmed in portable and benchtop photometers and a spectrophotometer.