Solubility chart

Abstract: Publisher Summary This chapter discusses the solubility measurements of amino acids and the related compounds mostly in aqueous solvents. Solubility is the concentration of the substance in question, which is at equilibrium with its solid phase at a certain temperature and pressure. The determination of solubility, therefore, requires the several conditions to be fulfilled. First, the establishment of equilibrium must be verified. This can be done in several ways. For instance, by assaying the solution after different periods of equilibration or reaching the same solubility value both from oversaturation, such as by cooling the solution saturated at higher temperature and from under saturation—that is, the normal way of saturation. Second, the solid sample must be pure. If the sample is not pure, the solubility will normally show a steady increase with increasing amount of solid phase, reflecting the decrease in activity coefficient because of the interaction of the impurity with the substance in question. Incidentally, this phenomenon serves as a criterion for the purity of a sample. If these conditions are fulfilled, the solubility must be a uniquely fixed value. However, there has been reported more than one value for the solubility of some amino acids.