| 摘要 |
The invention provides an electrode for use in determining the total concentration of tree ions in a test solution, the electrode having the property that the variation of its electrode potential with the logarithm of the sum of the free ion concentration-mobility products of electrolyte solution in electro- chemical contact therewith is linear with an intercept and slope which are constant for a given temperature and pressure, and the electrode being unselective and not distinguishing between different free ions. The electrode comprises a reference electrode R, preferably Hg/Hg2Cl2/Cl<-> or Ag/AgCl/Cl<->, in contact with a special solution 4 which in turn contacts the test solution, both contacts preferably being via liquid junctions 3,5. The special solution 4 is a solution of at least one strong electrolyte having a pH close to neutral and with mobility or weighted mean mobility of its cation(s) significantly different from that of its anion(s). One such electrode and another such electrode or a reference electrode form a cell whose constants are obtainable experimentally and from whose measured p.d. the sum of the concentration-mobility products of the free ions of the test solution is obtainable. From this sum the free ion concentration in the test solution is calculated or approximated. Measurement of test solution pH allows adjustment to be made for the presence of H<+> and OH<->. <IMAGE> |
