In water solutions, spectral-kinetic parameters of quantum dots based on the mixture of semiconductors of I-III-VI groups, namely Ag-In-S, Ag-In-S2 with ZnS layer (QD AIS/ZnS), show a specific dependence on pH and the local polarity caused by the interaction with polyelectrolytes (spectral shifts, hyperchromism and hypochromism in absorption and photoluminescence spectra, changes of the photoluminescence mean decay). It was argued that changes of QD AIS/ZnS upon variation of the solution pH are caused by the reversible recharging of ampholyte ion groups, which thus alters the structure of the Helmholtz binary layer at the QD surface covered by glutathione molecules. It is shown that the second derivative of QD absorption spectra both in an acid medium and upon interaction with polyelectrolytes corresponds to the Stark linear effect caused by the formation of the QD induced dipole moment. The results obtained and the corresponding conclusions on their basis may be used to develop selective markers for testing local pH and polarity in biomedicine using QD AIS/ZnS.