pH-ELEKTROD MED ÖPPEN FLÖDESZON / pH-electrode with Free-flowing Junction
Most problems associated with pH measurement with electrodes are related to the failure of the reference half-cell to maintain constant potential. The problem is most obvious when making pH measurements on two sample solutions with a great difference in ionic strength. An example would be when a pH meter is standardized with a buffer of known pH and high ionic strength and then a sample of low ionic strength like lake water is measured. One way to overcome this would be to use diluted buffers and add a small amount of supporting electrolyte to both buffers and sample. However, this practice introduces other possible errors and is not recommended by Statens Naturvårdsverk. Statens Naturvårdsverk made a survey of electrode performance in low ionic strength water. The results were published in 1983 and they clearly showed that gel-filled (sealed) pH-electrodes were not suited for this application. Electrodes of conventional design performed much better. “Complete abstract not presented.”