Secondly, we collected data on the distribution of spiked drugs in milk products using the pH, pKa, logPN and logD6.8 reported in the original work. 98,99 However, ionic partition was obtained from ChemAxon, except for the oxytetracycline (OTET ), for which the experimental logPI app was found in the literature 100 and used to measure the logD6.8 using Eq. 1 and Eq. 2.