meltingcurve

Melting curve refers to the relation between temperature and a property used to identify the melting transition of a material or system. In phase diagrams, melting curves trace the boundary between solid and liquid phases as a function of pressure or composition. Experimentally, a melting curve is often obtained by heating a sample and recording a property that changes abruptly at the transition, such as heat flow or optical appearance.

In materials science and physical chemistry, melting curves are measured with techniques such as differential scanning calorimetry (DSC), differential thermal analysis (DTA), or hot-stage microscopy. The onset, peak, and completion temperatures provide the melting temperature (Tm) and enthalpy of fusion. The curve's shape can reveal polymorphism, impurities, or phase transitions in complex mixtures.

In molecular biology, the term melting curve also appears in melting curve analysis after polymerase chain reaction (PCR). Fluorescent dyes monitor double-stranded DNA as temperature increases, producing a derivative melt curve that peaks at the melting temperature (Tm) of the amplicon. Melting temperatures help assess product identity, detect single-nucleotide variants, or confirm specificity.

Limitations include dependence on heating rate, sample geometry, and purity in materials; in PCR-based approaches, salt concentration, DNA length, GC content, and dye chemistry influence Tm and peak shape. Proper calibration and reference standards are important for robust interpretation.