Copper(II) ion-selective electrodes based on dithiosalicylic and thiosalicylic acids

Potentiometric carbon paste electrodes for copper(II) based on dithiosalicylic and tbiosalicylic acids are described. The sensor based on dithiosalicylic acid (DTS) exhibits a linear response with a nearly Nernstian slope of 27.7 mV per decade, whereas the electrode based on thiosalicylic acid (TS) shows a super-Nernstian slope. The limits of detection for the DTS sensor and the TS sensor are 10(-7.9)and 10(-6.3) M for copper(II) activity, respectively. Selectivity coefficients are tabulated, and the influence of the pH on the response of these ISEs is studied. The DTS electrode is successfully used for potentiometric titration of humic acids with copper in order to get more information about complexing properties of these acids.