Incidence of the melting-degradation process of vitamin C on the determination of the phase diagram with acetaminophen enhanced by high performance liquid chromatography tools

Compounds that degrade upon melting, such as vitamin C, are not convenient for temperature-composition phase diagram survey. To bypass such a disadvantage, faster scan rates may be used to heat the samples. However, in that case, the thermodynamic solid-liquid equilibrium cannot be reached as the present study demonstrates regarding the vitamin C-acetaminophen phase diagram determination. In this work, high performance liquid chromatography has therefore been used as a complementary tool with differential scanning calorimetry to determine the appropriate liquidus point for various mole fractions of vitamin C-acetaminophen. Because a classical thermodynamic approach is not sufficient for such a study, the analytical experiments that we have conducted provide useful data, allowing us to determine the non-degraded vitamin C quantity in the vitamin C-acetaminophen mixtures treated at a given temperature and annealing time.