This communication displays the results of preliminary studies of pH measurements of big ionic strength saline solutions applying the recent concept of unified acidity scale, pH abs , in comparison with the routinely potentiometric pH measurements. To this purpose, a set of sodium chloride solutions with salinity between 20 g $kg^{-1}$ and 230 g $kg^{-1}$, a standard seawater (OSIL) with a determined salinity value of 37 g $kg^{-1}$, and of added sodium chloride to OSIL within the same salinity interval were prepared. The salinities of these solutions were determined by refractometry and by densimetry, as the mass fractions measurement results by these two methods were evidenced to have metrological compatibility in the studied salinities interval. For the sodium chloride aqueous solutions, the results showed that the differences of pH values observed, $\Delta$pH, did not follow any tendency with respect to the salinity values and the displayed differences of ionic strengths do not manage to explain the behavior of $\Delta$pH for these solutions. In the OSIL solutions, the difference of pH lied in the small interval [-0.04;0.11], which is consistent with expected result. The higher difference between the pH values measured in unified scale and pH values measured by potentiometry for the OSIL solutions was 0,11 which is consistent with residual liquid junction potential errors that occurs during calibration when the ionic strength of the calibration buffers is different from the unknow solutions under test.